Practical Shaft Sinking

PRA C T I C AL SH A FT SI N KI N G

B Y D NAL CI O DSO M . E. FRAN S N , l C IﬁEF ENGI NEER

THE T . A. GI LLESPI E COM PANY

SEC’OND EDITION

Corrected with two new Appendices

M cG R AW — H I L L B OOK C OM PA N Y 239 WEST 39TH STREET NEW YORK , T E T L ND N E 6 S R E O O C . BOUVERIE , , 1 91 2 Co ri ht 19 10 1912 b the C RAW- I L B oox COMPANY py g , , , y M G H L

The Plimton Press Norwood Ma . p ss U. S. A. PREFACE TO THE FIRST ED I TI ON

THE subject matter of this book was published as a Min s and Mimrals u 1909 series of articles in e , d ring and 1 s i 1 9 0. It is reproduced , with ome alterations and add

n u Mr. tio s , thro gh the courtesy of Rufus J Foster, manager, M d Min r ine an als. r B . v s e and M . Eugene Wilson , editor of The writer also wishes to acknowledge his indebtedness to t Mines and Mine mls r H H . Soe M . . k, who was editor of when most of the articles came out .

e e 1 910. S ptemb r,

PREFACE TO SECOND EDI TI ON

SINCE the text of the ﬁ rst edition of Practical Shaft ” o n u Sinking was written , cement gr ut has bee sed in several American shafts to cut off ﬂows of water encountered in

sinking , and its further use for this purpose will undoubtedly i become more common . The writer , therefore , bel eves that a description of the methods used in grouting off ﬂows of water in two of the city aqueduct shafts (Catskill Aqueduct x Project) will make an interesting appendi . Such a de

scription is given in Appendix A. It will be noted that in one of these shafts a stratum of loose sand prevented the u entire excl sion of the water by grouting alone , that a

concrete lining provided with drain pipes was placed , and that the shaft was ﬁ nally made entirely dry by grouting

this lining . Several of the city aqueduct shafts in Brooklyn and the lower east side of Manhattan Island were sunk through great depths of water- bearing sand by the pneumatic cais A son process . section of one of these caissons , accompanied V V i PREFACE by a description of the methods used in sinking it and seal in i B g it to the rock , is shown in Append x . One change has been made in the shaft records on page 83 ne i to accommodate a w Amer can record . Several foot t and no es have also been added , one or two typographical errors corrected . CONTENTS

CHAPTER PREFACE I SOME DEEP SHAFTS FEATURES OF CONTRACTS FOR SINKING FORM OF CONTRACT

PLANT E UIRED B OILERS OI TING NGINE HEAD- RAME II R Q , H S E S, F AND BUCKET AmComp nnssons

III SI NKI NG THROUGH SURFACE SOFT GROUND WOODEN SHEET ING TEEL SHEETING CAISSONS OF TEE n n S S L, Woo , o CONCRETE IV SINKI NG THROUGH Sorr GROUND PNEUMATIC PROCESS SHI ELD METHOD

V SI NKI NG IN Rocx ARRANGEMENT or HOLES TOOLS AND METHODS USED IN D RILLING Cos'rs AND SPEED VI THE SINKING-DRUM PROCESS MAMMOTH PUMP THE FREEZ I NG PROCESS

VII THE KIND-CHAUDRON BORING Pnocnss CEMENTATION or WATER-B EARING FISSURES

P H D VIII LIFTING WATER HORIZONTAL v s. VERTI CAL UMPS AN LING PUMPS IN SHAFT Coa sn PUMPS

I X SHAF' I‘ LI NI NGS

X CONCRETE LIN IN GS Cos'rs PER LINEAR Foo'r FOR RECTANGU LAB L IPTICA AND UADRILATERAL SHAFI ‘S E L L, Q

PPE I RO TING HAFT 4 AND 24 N. Y. ITY UEDUCT A ND X A. G U S S , C AQ N

B .

PRACTICAL SHAFT SINKING

CHAPTER I

' SOME DEEP SHAFTS FEATURES OF CONTRAo'ps FoR I SINKING — FORM OF CONTRACT

THE mini in u origin of ng is lost the mists of antiq ity , ni but it is certain that , since the begin ng of history, metals u and minerals have been so ght after . The Egyptians operated gold , silver , and copper mines in Ethiopia and on the Arabian border ; the Phoenicians found gold and iron in the islands of the Mediterranean and lead and silver i in Spain . The earliest mnes were probably snrface work ﬁ r ings , but the st historical mention of openings driven in ri but the earth refers not to a d ft or tunnel to a shaft . In “ the Book of Job it is written of man that He breaketh open a shaft away from where men sojourn ; they are for gotten of the foot ; they hang afar from men ; they swing to ” “ u : and fro . Pliny describes c tting hitches in a shaft Else where pathless rocks are cut away and are hollowed out to He u u furnish a rest for beams . who c ts is s spended with

ropes . Shaft sinking and tunnel operations in ancient times

were conﬁ ned to solid earth and rock . The Roman engi neers drove rock tunnels that would seem long to-day ; they originated the method of disintegrating rock by ﬁ re and they sunk shafts along the line of their t unnels from which to

drive additional headings . Forty shafts one of them f u 400 t. deep were sed for the excavation of their longest

tunnel . ? For many centuries after the Roman Era nothing com

parable to the Roman work was attempted , since the cost in labor and human life of the ﬁ re—and—water method was PRACTICAL SHAFT SINKING

i was terriﬁ c. The nvention of gunpowder the next step , but gunpowder was apparently not used for blasting purposes

1 679 . s in r until , at Malpas , France Mine the Ha tz Moun tains and in Cornwall had been worked to great depths in the seventeenth century before the steam engine was e li e d veloped , but its app cation to hoisting of course mad 1n fi rst bossfiflé undreamed of speed sinking . The practical

i ﬁ rst i hi The invention of dynam te , the commerc al gh

i 1 866 - air 1855 u t explos ve , in , and the compressed drill in , p rock shaft sinking on its present basis. Although from time to time special methods such as the freezing and the r i i bo ing processes have been developed for spec al cond tions, i for ordinary shafts hand s nking is cheapest and best . i i i confi ned Excepting the steam ho st , nvent ons have been to means for shattering the rock ; steam shovels are some u i - times sed in tunnels , but shaft spo l is to day loaded by hand into buckets , as in the days of the Romans . u s Before the last half of the nineteenth cent ry, oft ground sinking was confi ned to material penetrable by fore poling . Although considerable depths have been reached is i t in this way , where the ground bad the method s at bes slow and precarious . The Germans originated the hydrau licall Th y forced sinking drum and the freezing process . e pneumatic process was fi rst used by Brunel in the Thames

. i Tunnel Recently , concrete s nking drums or open caissons have been extensively used . The sizes and shapes of shafts are governed by the nature r of the material to be hoisted th ough them , by the char acter of the ground to be penetrated , and also largely by local usage . Since mine cars and skips are approximately rect mi e angular in plan , a rectangle is the most econo cal shap i for a hoist shaft , g ving the maximum usable area with the minimum excavation ; this advantage , however , does not apply to an air shaft . The rectangular shape is also adapted i to timbering, the cheapest form of lining, and is on th s SOME DEEP SHAFTS 3

Am account standard in erica . In Europe, on the other i hand , all shafts are circular or elliptical and are l ned with i brick or concrete masonry . Th s type has the disadvantage i ﬁ rst r ni of h gh cost , but a mason y li ng is proof against ﬁ re . decay and and explosions In wet strata also , a circular shaft may be lined with iron tubbing and thus kept entirely dry . In large mines two openings are always advisable to secure satisfactory ventilation ; in coal mines where explo sive gases form they are absolutely necessary , and in most i states are required by law . The ho st shaft may be upcast or downcast in either case an airway is usually provided in A11 mi addition to the hoist compartments . nes worthy of the name have balanced cages requiring two hoistways ; the airway makes a three- compartment shaft the most common type . In rectangular shafts , where several com artments p are needed , a long shaft one compartment wide is easier to sink and timber than a short shaft two com

artments i 7 10 ft. p wide ; for nstance , if four X compart 2 ft is 1 0 8 . ments are desired , a shaft X preferable to one

20 X 14 ft. i i ﬁ elds i In America , in the b tum nous coal , ho st shafts 1 i i 8 0 n. 1 26 ft. are usually 3 x in the rock , are lined w th X 9 1 1 ft 1 1 . timber and have two 7 X ft. hoistways and a x

- i a . 5 ft. ew airway . In wet mines a p p y is added The air 1 1 ft -ft 1 1 . r 6 . 1 ft. 0 shafts are 3 X 8 , with a x ai way and a s ﬁ elds tairway compartment . In the anthracite the deeper hoist shafts sometimes have four hoistways operating from several coal seams , besides air and pipe ways , and have

1 2 42 14 56 ft. . u sections x ft. to x in the rock E ropean ﬁ nished i r. coal shafts are customarily 20 to 23 ft. in d amete

Coal shafts are almost always vertical .

In ore mines different conditions prevail . Ore is less mi u bulky than coal is harder to ne , and can be loaded thro gh chutes without objectionable breakage . Large shafts are t therefore unnecessary and the sizes range from 7 x 9 f . P a. in the iron mines formerly operated at Boyertown , , 4 PRACTICAL SHAFT SINKING

in t 24 ft. to 9 X the Michigan iron coun ry . Ore n s shafts are usually su k on the vein , and o may be found i i r at any nclination w th the ve tical , but where natural l a i conditions do not compel an inc ination , perpend cular shaft is preferable .

i . 3 The deepest shaft in Amer ca , No Tamarack at Tama ft n 2 3 . is s mi . i s 5 5 . rack , Mich , deep and u ed in ing copper 1 ft k t r 5 80 . ac e No . 5 shaft at Tama ack is deep , Red J shaft 49 f 00 t. . at Calumet , Mich . , is deep These shafts are remarkable not only because they penetrate the earth for i almost a m le , but also because of the remarkably powerful hoisting engines used engines which hoist a total load of

1 . 7 tons at the rate of 6000 ft. per minute All of these shafts are vertical . h ﬁ elds In the Pennsylvania ant racite , where acid mine a u water quickly eats up pumps and piping , n mber of shafts The have been sunk for the purpose of hoisting water . tanks used for hoisting ﬁ ll and empty themselves auto maticall y, discharging the water into a basin at the top of the shaft . Powerful hoist engines are provided . The

. L e w d b D . most notable shaft of this typ is o ne y the ,

P . . . a W . R R , at Scranton , It is entirely automatic , r d h n equiring no engineer, and is operate t rough frictio

- - clutches by an 800 horse power induction motor . The driving of rock shafts and tunnels is very unlike the

3 . ff iff mining of coal ; di erent class of workmen , d erent fore ‘ mn iﬁ erent t s e , and d ool are needed . It is seldom that a

od - go coal mine foreman is also a good sinker , and good h t . sinkers , unattac ed , are not always easy to ob ain For these reasons it is customary for coal- mining companies to have a large part of their development work done by con tract , and even the large anthracite corporations , who own u the necessary surface eq ipment for sinking , prefer to have i contractors do the sinking . In ore m nes the foregoing does ’ not apply ; sinking shafts is part of the day s work and all i the miners are rock men , but in opening a new m ne the question of time is still to be considered . The loss of DISPOSAL OF SOIL 5 interest on the investment in a large property before it is

developed may amount to several hundred dollars a day, and every day lost in sinking adds that much to the cost ni of the shaft . Even when a mi ng company is so situated

that it can sink its shaft cheaply , a responsible contractor possessing a plant and an organization can save enough r ﬁ time to more than pay his p o t. n When it is decided to have a shaft su k by contract , the ﬁ rst essential is to get trustworthy contractors to bid on the job ; the second is to prepare a contract fair to both

sides . While it is not well to leave loopholes whereby the contractor can escape from the plain provisions of the speci ﬁ cations , it is equally unwise to attempt to tie him down so tight in every detail that he is practically dared to ﬁ nd a

ﬂaw in the agreement . It is almost impossible to foresee

n r - every contingency , and an omissio in a ve y tightly drawn contract is harder to correct subsequently than an omission

in a looser one . A complete shaft contract form may be found in several

- w difﬁ cult text books , or obtained elsewhere ithout y; a form

in common use is appended to this chapter . Among the speciﬁ c points that warrant attention may be mentioned the following : t Disposal of Spoil . The labor cos of a shaft is of

course directly affected by the nature of the dump . It is ff e also indirectly a ected by it to an ev n greater extent . The delays to sinking caused by a long haul and an incon v enient dump , especially in bad weather, are likely to be i more serious than the cost of the add tional labor required . s eciﬁ cati ns The p o should , therefore , state where the spoil

is to be dumped , or at least where it is not to be dumped . s In one ca e where a contract contained the usual clause , the S n poil shall be placed where the e gineer shall direct , the haul 1 not to exceed 500 no plans were available , and in the

absence of any direct prohibition by the engineer , the con

tractor started to dump spoil in the vicinity of the shaft . f ’ d A ter three months sinking , the engineer iscovered that 6 PRACTICAL SHAFT SINKING the dump was in his way and directed that the spoil be l e placed elsewhere . Subsequently he compe led the contra tor , under the clause cited above , to move all the spoil ﬁ rst hi hi a dumped in the three months . W le in t s c se the ’ mi l engineer s order ght have been successfu ly contested , much trouble could have been saved by proper care in drawing up the contract . T P n -l i ime Limit and e al ty. A time im t clause is most properly a feature of nearly all sinking contracts , and the u usual provision made to sec re its enforcement is , and in the event of the contractor failing to complete the work by

. it this date , is mutually agreed that he shall pay the con tractee the sum of dollars for every day thereafter l until the work is completed , not as a penalty , but as iqui ” ti . hi ﬁ ni on dated damages In spite of t s de , the courts have often held that the actual damages must be proven and the possibility of collecting the stated damages is not assured . Since the real damages to a mining company due to delay in getting started consist of the loss of interest on the invest ment , in every case where the company has its surface ﬁ nished arrangements ready for work before its shafts are , it will gain as much per day by their completion ahead of

— i time as it will lose by their non completion . The wr ter therefore believes that where a penalty is to be collected for mi delay an equal pre um should be paid for time saved , not only because this is fair but also because it is likely to

. An u expedite the work extension of time is us ally, and “ be u should , allowed the contractor on account of unus al ” ti s h difﬁ cul e wit water or quicksand .

Acceptance. Where two shafts are sunk simultaneously t under the same contrac (as in opening a new coal mine) , the ﬁ rst shaft down is usually accepted by the company upon

' it completion . If this is not the intention should be so stated in the contract . Risk f r con o Wate . It has been the practice in shaft tracts to throw the risk of encountering unusual quantities ﬁ xed of water upon the contractor . With a price per foot SUPPLIES AND MACHINERY 7

i for sinking , based upon usual cond tions , the contractor will if 1 50 lose money he strikes water exceeding, say , gallons per i his minute . With greater quant ties loss is often measured

only by his ﬁ nancial resources . This puts a responsible i ri contractor at a d sadvantage , especially in a new ter tory , for since he has the equipment and the money needed to ﬁ ht g large quantities of water, he must raise his price on all An shafts to insure himagainst an occasional heavy loss . r i l i responsible contractor, on the other hand , hav ng ittle ff if r to lose , can a ord to bid low, and he does st ike much r water abandon the job . Thme water isk belongs properly not to the contractor nor the ine owners in general , but to the owners of the particular mine in question ; for this reason

a water clause is a feature of many recent contracts . The Y New ork Board of Water Supply, in its contracts for the construction of the inverted siphons on the Catskill aque l duct , calls for a price for pumping each mil ion gallons of 1 ft l water . In these jobs the time schedules are so carefu ly worked out that there is little likelihood of the contractor roﬁ t pumping water for p , but a form of water clause more acceptable to the average mining company is one in which the contractor makes an additional price per foot for every i hundred gallons per m nute pumped while sinking . He is thus paid nothing if the shaft is idle and is encouraged to

make progress. u s nd M chin r i i S pplie a a e y. Local cond tions determ ne whether the mining company or the contractor should l furnish the supp ies or machinery . The larger anthracite

companies , who hold extensive properties and open new e own i e mines upon them as the ne d arises , sink ng ngines ,

boilers , and other equipment at a new shaft they erect a u surface plant complete , f rnish timber and coal , and expect su l ' onl the contractor to pp y y the air compressor and drills , s ﬁ lds . i e mall tools , and labor In the bitum nous and in i many ore regions , the m ning companies usually wish to u develop new property as soon as it is acq ired , and , in order to concentrate their efforts upon the permanent surface 8 PRACTICAL SHAFT SINKING

x ni plant , e pect the shaft contractor to fur sh everything i a . m he needs A qu cker start can be de in this way . If the i me shaft is to be t mbered , however , the ti b r should be Oak i furnished by the company . su table for shaft linings is rapidly becoming unobtainable ; yellow pine must be brought long distances and is not likely to arrive too soon

if ordered when the shaft contract is let . Aside from the i question of speed , the company by supply ng timber will roﬁ t save itself the p that the contractor adds to cost, and

also occasional vexatious squabbles as to quality . No matter how the shaft is sunk the permanent boiler plant should be made ready to operate as soon as is prac l ticab e. The possibility of striking water is the greatest

hazard of sinking and , if water is encountered , the ﬁ rst

requirement is plenty of steam . It is easier and quicker to procure and install any amount of pipe and any number of the pumps than it is to build a boiler plant to run pumps . Effective sinking pumps are so exceedingly wasteful of steam that the permanent mine boiler plant will be none too large and effi cient to care for a large inflow of water ; its e i arly completion w ll insure against a long and costly delay . The local flow of underground water is one of the most

uncertain features of geology , and whether or not water will be encountered in a given shaft can seldom be predicted

with certainty . Even when borings at the site of a shaft or other shafts sunk in the vicinity indicate that water will

be struck, the amount is problematical . A few general remarks may be stated as follows the Since the rainfall in mountains is high , ground near G i them will have an opportunity to collect water . eolog c faults form passages whereby surface water ﬁ nds its way n ﬁ ssures i to the ground , and the caused by the strain to which the rock was subjected when the fault was made act wot as reservoirs . A shaft on or near a fault is sure to be

- below the ground water level of the surrounding region . Natural water courses also form in soluble rock such as s An andstone and limestone , especially the latter . example SOME DEEP SHAFTS 9 of a water course of this kind was afforded at the zinc mine P r dr ” at a. i Friedensville, , fo merly ained by the Pres dent ,

the largest Cornish pump ever built . This mine is located

at the foot of a mountain . Two shafts sunk inthe Allegheny Mountains near South

P . a. Fork, , also encountered a water course They were ar about 250 ft. apart and app ently were sunk directly on

top of the water channel . What may be called the down stream shaft was sunk fi rst through the wet stratum ; as the -s nk flow up tream shaft was su the into it increased , while the fl i w - ow nto the do n stream shaft decreased at the same rate . Shafts near streams are likely to strike water at the sur ss it face of the rock , but not nece arily below if the rock is i s sol d . In ordinary coal mea ures a feeder may be expected at s m rm s s the ea between an upper pe eable rock like and tone , i i s fi recl and a lower bed of mperv ou shale or ay. The uses of the diamond drill in prospecting for coal and r n o e are too well know to require comment , as far as the a knowledge obt ined of the rock is concerned . A hole near a proposed shaft will also give much information as to the r - di i i g ound water con t ons, even though, as has been sa d,

rmi . the quantity cannot be detemned A diamond drill hole is not large enough to pu p out , but the process may ‘ I f i i be reversed . add t onal water can be pumped into a hole already full , the strata are evidently open enough to let water into a shaft . A bore hole, of course , may be pumped with a deep-well pump or air lift it has in fact been suggested that wet ground be drained by pumping f r i rom a ring of bore holes a ound the shaft locat on, thus i doing away entirely w th pumps in the shaft . s Prospect holes should be located at one side of the haft, so that if a pocket of water is drilled into at a considerable it i depth , w ll not rise into the shaft through the hole . In this way pumps and piping need not be installed until the bottom of the shaft has almost reached the level of the pocket , and the depth of the wet sinking is reduced to a minimum . 1 0 PRACTICAL SHAFT SINKING

. CONTRACT AGREEMENT FOR SHAFT SINKING This agreement made in duplicate this day of

Co. by and between the Coal , a corporation chartered and existing under the laws of the State of fi rst party of the part , and the Con n Cc. r tracting , a corporation cha tered and existi g under the s laws of the State of party of the econd part , SS in WITNE ETH , That for and consideration of the cove nants and payments hereinafter specifi ed to be made and per fi rst formed by the party of the part , the said party of the second part doth hereby covenant and agree to build and complete in the most substantial and workmanlike manner, a 1 2 3 6 ft. hoisting shaft x , outside the timbers , and an air

13 18 ft. r 6 shaft x , outside the timbe s , each approximately 00 f t. Cc. deep , for the Coal , at its property near The work is to be done in accordance with the attached specifi cations and the plans furnished by the party fi rst of the part , which are hereby made a part of this agree ment ; the party of the second part is to furnish all the labor a and materials necessary , except such as are particul rly noted in the specifi cations as being furnished by party of the fi rst part . The said work is to be completed on or before the first day of 1 9 And the party of the fi rst part doth promise and agree to pay the party of the second part the following prices for s ecifi ed the the several kinds of work herein p , of which following is a summary :

Hors'r SHAFT

Excavation measured from top of natural ground to bottom of

ft. coal seam 3 per vert .

l m ft. Framing and p ac g all timber and lagging 3 per vert . s Water ring complete 3 each .

AIR SHAH

Same as above.

1 2 PRACTICAL SHAFT SINKING

or and material men for work done on or about the shafts, for materials furnished for the work under this contract . It is further agreed between said parties that said party of the second part shall not transfer or sublet any part of this contract to any person (except for delivery of materials) fi rst without the consent of the party of the part , and that the party of the second part will at all times give personal attention to the superintendence of the work . It is further agreed that the work embraced in this contract shall be commenced within two (2) weeks of the date of this contract and prosecuted day and night (except n Sundays) with as ma y men as can be worked to advantage . I f , during the progress of the work , it is the opinion of the Engineer of the party of the fi rst part that the party of the second part is not furnishing materials or appliances or labor suffi cient of the right quality , or in quantity to complete the on work within the time agreed , the said Engineer may in either or both of the above- mentioned cases purchase such material and appliances or employ such labor as in his

judgment may be necessary . And the said Engineer is authorized to pay such wages for labor and such prices for materials and appliances as may be found necessary or d m expe ient , and to deduct the a ount so paid from any moneys due the party of the second part from the party of ﬁ rst the part . It is further agreed that the Engineer shall have the authority to order any additional work or materials not called for in the plans and speciﬁ cations that he may deem s necessary or advisable , but in ca e any such extra work or s materials is required , the same hall be ordered by the the Engineer in writing , and price for said extra work or materials shall mutually be agreed upon in writing before

said materials are furnished or said work is done . I N WITNESS WHEREOF the parties herein have hereunto

set their hands and seals, the day and date ﬁ rst above

mentioned . CONTRACT AND SPECIFICATIONS 1 3

SPECIFICATIONS FOR SINKING AND LINING Two SHAFTS L P Y T FOR THE COA COM AN , A GENERAL

M nn f Titles. ea i g o The word Contractor, when here inafter used , shall refer to the Contracting Company as in the attached Agreement . The word Engineer shall hi refer to the C ef Engineer of the Coal Company, or his representative .

Labor and Materials Furnished . The Contractor shall ni i fur sh all machinery, tools , labor, mater als , and supplies i ncidental to , or in any way connected with, the sinking and timbering of the two shafts hereinafter described , with the exception of the timber which will be furnished by the Coal Company free on board cars at ’ Location of Temporary Plant. The Contractor s hoist ing apparatus and temporary machinery and buildings shall be so placed as not to interfere with the construction of the

- permanent head frames, or the erection of the permanent plant . EX CAV ATION 1 3 2 f The dimensions of the hoist shaft shall be x 6 t.

and 13 18 ft. of the air shaft X , outside of lagging . The excavation shall be carried down square and plumb from top to bottom and be large enough to give room for the proper wedging of the timber . Special care must be exercised in blasting to avoid shattering the walls of the shaft , and all loose material which might endanger the timbering or the men working below must be removed . The Contractor shall keep his machinery and tools in i good cond tion , and take every reasonable precaution to insure the safety of his men . The Contractor shall deposit all material excavated from the shafts at places directed by the Engineer , to con form to the grades established adjacent to the shaft . Any overhaul exceeding 500 ft. shall be paid for at the rate of 1 f 0 t. cents per cubic yard for each 0 of overhaul . 14 PRACTICAL SHAFT SINKING

The depth of the shafts shall be measured from the elevation of the original surface of the ground in the center s of the shaft to the bottom of the coal eam .

TIMB ERING

The shaft shall be timbered throughout with sound oak i u i e or yellow p ne to be f rn sh d by the Coal Company . It is to be framed accurately by the Contractor according ’ to the Coal Company s plans and shall be placed in the

i . shafts square, level , and to l ne buntons s s l Wall plates , end plates , , and po ts ha l be i i r sh 1 . 8 12 8 0 n e in. X , and b ar ng or hitch timbe s all be x

- i 2 in . lagging shall be of . plank The lagg ng shall rest on a 2 4 i i i X h . oak p ece placed horizontally in the m ddle of the back of each end and wall plate and well spiked ; the space between the lagging and the rock shall be backed solid with sound slabs or other sound refuse timber . Each corner of each ring of timbers and each wall plate at both ends of every bunton shall be thoroughly braced against the side of the shaft by blocks and wedges . The sets

5 ft. of timber shall be apart vertically , center to center . At r f hi i t. s inte vals of 50 vertically , bearing or tch t mber shall be placed to serve as supports to the timbering above . The hitch or bearing in the rock at each end of each timber shall be strong enough to develop the full strength of the n i . timber ; in no case shall it be less than 8 in depth . The i r f nte vals of 50 t. may in the judgment of the Engineer be i s varied , but no such var ation shall be made by the Con tractor without the consent of the Engineer . The timbering shall be carried above the natural ground i i in to the level indicated by the Engineer . Spec al t mber g shall be placed at the shaft bottom in accordance with the u i plans f rn shed .

1 - in The air compartment shall be lined with . tongued f i l and grooved yellow pine loor ng, free from knots and we l s matched and joined on end and wall plates . The guide all s 8 in. shall be 6 X yellow pine surfaced on faces, and hall CONTRACT AND SPECIFICATIONS 1 5

s an be framed as hown on plan d placed exactly plumb , and straight and true to gage from top to bottom .

WATER RINGS The water rings shall be constructed before the timbering

is ﬁ nal . l y placed , and shall be as shown on the plans The

ri - f bottom of each ng shall have a water tight loor of concrete . The number and location of the water rings shall be deter mined by the Engineer .

’ U SE OF CONTRACTOR S PLANT The Coal Company shall have the privilege of renting the Contractor’s hoisting and pumping plant after the com letion 2 s p of the shafts for a period of two ( ) weeks . It hall pay the Contractor perday as rental for said plant . CHAPTER II

B OI LERS S ENGI NES PLANT REQUIRED , HOI TING , HEAD FRAME AND BUCKETS AI R COMPRESSORS

PLANT

I N considering the subject of shaft sinking from the m i ﬁ rst n echanical s de , the and most important consideratio r is the proper design and arrangement of the su face plant . r i The underg ound plant comprises rock dr lls and pumps , and both above and below ground many tools and con triv ances are required . The items included under surface plant will be treated ﬁ rst and the underground contrivances taken up later in connection with the work which they perform . The elements of a modern surface plant are : Primary power producer ; hoisting apparatus secondary-power pro

ducers s . ; building , shops , etc - r Al Primary power Produce . though in a few favored localities electric power may be cheaply bought and used di air e e n rectly , or converted into power when ne d d, in ine r tenths of the shafts sunk the p imary power is steam . The boiler plant , in this case , is the backbone of the job ; it must be put up to allow of expansion if necessary , and it must be absolutely reliable . In other forms of construction work , t wa er , while always a source of trouble and expense , is not the implacable enemy that it is in sinking . The pumps

' d coflerdam it a which rain a will also serve to empty , and w breakdo n delays the work only until repairs are made . t th In a wet shaft , on the other hand (par icularly where e ’ i are ord nary types of sinking pumps used) , an hour s lack of steam may submerge the pumps and allow the shaft to ll h fi . It will t en be necessary to get new pumps and fi ht piping and to g the water down again from the top , and 1 6 PLANT REQUIRED 1 7

weeks or months may elapse before sinking can be re

sumed . 2 for 5 300 ft. For a wet shaft or any shaft deeper than 0 or , the bricked-in return- tubular boiler is the most satisfactory r ﬁrin 15 20 type . Such a boiler bu ns under normal g to Th i . e per cent . less coal than the ord nary portable boiler a i 100 - difference in t he co l b ll for boiler horse power, with i h t coal at a ton , w ll , therefore , in t ree months, amoun 300 hi ri in 1 00 to $ , w ch is about the cost of b cking a horse

- s power return tubular boiler . The latter al o costs less for i repairs and is generally less trouble than the portable bo ler . l t i r For a short job the oil we l , or locomo ive type , bo le is 4 se the best . The size should be not smaller than 0 hor 60 - power ; horse power is better , as in the small sizes the crown sheet has such a shallow covering of water that it h is easily burned . The dome s ould be placed on the barrel w of the boiler ; if over the cro n sheet , the long stay bolts connecting the crown sheet and the top of the dome are likely B l to give trouble . y uti izing the exhaust from a compressor

or hoist engine , it is possible to force the locomotive boiler

to make steam greatly in excess of its rated capacity, and

this fact gives it a great advantage over other types . At coal shafts the boilers should be set far enough away to make it impossible for a sudden ﬂow of gas from the shaft to so become ignited . They should always be placed as to

minimize the cost of handling coal and ashes . The ground at one end of the line of boilers should be clear of buildings i or machinery, to allow of additional un ts being placed as i requ red . i s e i The pip ng hould also be arranged to p rmit expans on ,

not only of the plant as a whole , but also the temperature At expansion of the pipe itself . the open end of the line of i boilers the header should term nate in a valve , so that the additional boilers can be coupled on without shutting down the plant ; if so many boilers have to be added that a second a w ﬁ rst header is necess ry , it should be connected ith the at i ff m . both ends, for ng a steam loop Sti connections between 18 PRACTICAL SHAFT SINKING the boilers and the header are objectionable and are likely to cause leaky joints . l A constant supply of feedwater must be assured . Dup i

- s cate feed pumps or injector , or a combination of the two , should be provided , and the pumps supplying water from a l stream to the supply tank should also be in dup icate . A good feedwater heater will cut the coal bill surprisingly 10 r 1 . to be accurate , per cent for every degrees the feedwate ° F an 50 . . m is raised Assu ing the feedwater at , originally , Open heater with plenty of exhaust steam will raise its temperature to 210° and reduce the fuel consumption 1 6 i for per cent . With coal at per ton , a heater w ll pay

FI I s - a —s ess 1 . G . nger oll R nd Two tage Straight Line Air Compr or

1 An . is itself in two months . open heater as shown in Fig more effi cient than a closed heater and maintains its effi ciency; it has no tubes to leak and become covered with scale ; it saves the pure water formed by the condensed r exhaust steam , and it is adapted to various systems of wate n in i h urifi catio . p It must , however , be used connection w t a good separator for removing the oil from the exhaust . A satisfactory feedwater system for a plant containing several boilers may be arranged as follows : Feed all boilers

. in from a common header Provide regulating valves , addition to regular check and boiler- stop valves in con nections t between header and boilers . Supply water o header with pump large enough to feed all boilers with

f . 50 t . h r piston speed of per minute Use ard rubber, o

20 PRACTICAL SHAFT SINKING thousand boiler horse-power has been used for three very wet

“

f m m o . sha ts , only two of the being worked at si ultane usly i s r the Hoisting Apparatus. For sink ng a haft th ough - i su soi all stiﬁ ri s s . rface l , a sm leg der ck u ually erected This makes excavation and timbering cheaper than if done r i n e by hand , and it does not inte fere w th placi g the surfac concrete or add weight to the ground around the shaft .

- - f 0 ft. s i i a 40 t. 3 A derr ck w th boom and a ma t , built of 1 2 12 n is i . b i . i e X t mber, large enough for sink ng It can 1 - readily swung by two men at the end of a 0 ft. lever bolted is to the mast . If any considerable depth to be sunk , this lever should be secured by some kind of latch to prevent the derrick swinging while the bucket is in the shaft . A double- drum friction engine is best for a derrick as it enables the engineer to raise and lower the boom , and also , 1 i i i 7 0 n. with the help of a winchman , to sw ng the derr ck ; X

1 i - and 8} X 0 n. are convenient engine sizes . A single drum sinking engine may be used to advantage on aderrick with a x ﬁ ed boom swung by hand . The fall line sheaves should be larger than are ordinarily used for a light derrick ; never less i 1 2 -in i 4 i . n. n. than 8 outside diameter , preferably A i rope

i 24- i wll work over a n. sheave without undue wear . Although a small shaft may be readily sunk with a der

f - 200 t. rick for , it is better to put up a head frame when the surface timbering or masonry is completed . Sinking head frames are often built unnecessarily large and heavy . A

- f 1 2 f 8 t. hé ad frame 40 t. high and X in plan is large enough for a sinking shaft . It may be built of timber, with 1 in i 8 0 in. in. 3 8 . 8 X 8 posts , X d agonal braces , X caps,

1 1 2 n . or i . and 0 X sheave timbers, as shown in Fig 3 , , if it is to be frequently moved , of steel . If built of steel ,

- n 6 X 6 X é i . angles will form posts strong enough to

- handle with safety a 5 ton pump . The sheave , as a rule , should not be smaller in diameter than the engine drum,

- l - in. . but a 48 in. wheel will give good service with rope Two methods are used for the disposal of the spoil

- ﬁ rst - hoisted by the head frame . In the a broad gage PLANT REQUIRED 21

track is extended under the frame so that the rope passes between the rails ; when a full bucket has been hoisted above

the track , a truck carrying an empty bucket is pushed under it , the full bucket is set on the truck, and the empty one an lifted . The truck is then pushed away d the bucket h dumped by a gallows frame or other device . T ree buckets are needed for this method so that one may be always in

the bottom .

- FI . s G . 3 Section of Sinking Head frame

i In the second and better method , tipp ng buckets must

A - be used . t one side of the head frame a chute is built , r high and long enough to discha ge spoil into a dump car, its upper end just clearing the bucket hanging free on the ”

. 3 . n rope , Fig O the cap above the chute a bull chain “ ” - is hung . The head man stands on a platform level with the top of the chute and , when the bucket is hoisted within

s . reach , hook the bull chain into the bail The bucket is

and . lowered slightly , swings out over the chute , is dumped s The complete Operation may be performed in 30 second . 22 PRACTICAL SHAFT SINKING

his i r - T method requ res only two buckets . Th ee quarter inch l common chain wil serve for the bull chain . Its book

. At should be provided with a handle a deep shaft , the bottom of the chute should be covered with pieces of old r a a ail l id lengthwise , and in rock that bre ks into large i u lumps a gate is adv sable to protect the d mp car . A small house is usually built for the head- man at the plat form level . i i r u 3 To facil tate hook ng the shaft ope to the b cket , or 4 f a i t. of ch in is nserted between the rope and the hook . The chain should be welded into a closed socket babbitted i 6 in. to the rope , and its l nks should be long so as to afford a good hand grip . Safety catches are provided on the hook . Shaft buckets are circular in plan and contain from to 1 di cubic yard , depen ng on the depth of the shaft and the i size of the engine . A ﬂared bucket , Fig . 6, d scharges rock i ni more freely than a cylindr cal one ; a conve ent size is 3 ft. 2 f 1 i 2 f 0 n. in i t. t . . 9 . 6 in top d ameter and bottom by high . The bail is secured to the bucket trunnions by straps and

i . bolts , so that it may be easily removed for repa rs A wooden inner bottom is sometimes used to cushion the blows from pieces of rock . Every bucket should have two latches , in and two lugs to prevent its dumping the wrong direction . The dump car that will not be knocked to pieces by large i rocks falling from the chute must be very strongly bu lt . liﬁ ati ns Its other qua c o depend on the nature of the dump .

Ordinarily , where the dump is close to the shaft , and the car

- - 36 in. is pushed by hand , a gage , all around dump car , with wheels loose on the axle, is best . The simpler the construction the better .

- A cheap and easily erected head frame , for use when the r e regular plant is not available , consists of a t ipod mad of i t three poles bolted together at the top . This s se up over the excavation , a snatch block is attached at the top and another at the foot of one of the legs , and small buckets are hoisted by a team of mules, pulled to one side and dumped PLANT REQUIRED 23

on a platform by hand . The buckets are made out of a half

ﬁ tted . oil barrel , with extra hoops and a bail

‘ 1 i 8 0 n. 50 ft. For depths of less than 0 , an 1 X double

- 41 - cylinder end friction hoisting engine with a in. drum will do satisfactory work . The friction and brake levers o most conv enient the are if set in a stand back of drum , as is customary with larger engines . Both should have latches ; An on the brake lever a latch is imperative . engine of this

2 00 . 350 f size will hoist a loaded bucket weighing 5 lbs t. in hi n a minute ; a round trip from t s depth , i cluding dumping the bucket , can be made in two and a half minutes . A f t 5 t. depths greater than 00 , the weight of the rope and the long hoist make a larger engine necessary . Rever sible link- motion geared engines similar to that shown in 7 1 0 1 2 i Fig . are generally used , the sizes varying from X n.

in - i to 14 X 20 . First motion engines are somet mes used 1 ru . 1 for great depths A 0 X 2 in. geared engine nning at 4 0 a speed of 0 ft. per minute has a hoisting capacity of 4 f 5 0 . 80 t 0 0 . lbs , and will handle muck from a depth of The drum should be grooved so that the rope will wind regularly and not cut itself . The size of rope used for i in 1 in. . u sinking runs from i p, but sizes greater than are

l - n - h i . as unnecessary . A crucible cast steel rope a breaking

of 34 . strength tons ; it weighs lbs per foot , and there

- l 300 b. fore , when hoisting a 0 bucket , has a factor of safety 1 1 ‘ 2 ft. of at a depth of 000 This factor is ample , and there di is no use in consuming power in hoisting ad tional weight . i s Many l ves depend on the brake of a inking engine , and it should , therefore , be made large and strong beyond possibility of fracture . In the case of a band brake , the diameter of the part of the drum gripped by the band s r hould be as great or greater than that of the d um itself, and the lever should tighten the band in the direction of b the pull of the rope , the other end of the and being rigidly

o i . attached to the frame i. the eng ne A good brake , capable r of stopping the d um every time within an inch of the mark , s s s is not only a afeguard, but a great a si tance to sinking,

‘ ‘ WM “ Qs? C M JF O 24 PRACTICAL SHAFT SINKING especially in setting up the bar and machine or in handling timber . - i ss r e a Double drum eng nes , nece a ily friction operat d , re r built for sinking purposes , one d um being used for the bucket , the other for handling pumps, piping , etc . The s second drum introduces another set of gear , causing addi r tional friction and wear, even when unning idle , and costs i h as much as a small independent eng ne , w ich is in every

- n - . li way preferable A compound geared , reversible k motion i rr engine , of the type used for swing ng de icks , makes a good 7 i 8 n. i engine for handling pumps . The X size w ll hoist

7 . i 000 lbs . on a single rope The eng ne can be started and stopped just where desired , and there is no danger of a heavy load getting out of control . Electric hoists are now built by several ﬁ rms in sizes equivalent to their standard steam engines, and operate satisfactorily with various types of motors . Gas engines n have found a very limited application to hoisti g , but small gasoline hoists can be bought . Signals are given the engineer by a bell in the engine house . It consists of a small whistle or a hammer striking

- a triangle , and is operated by a wire leading to a bell crank h f n the s a t . o top of , thence to the bottom A coil of wire is usually clamped to the horizontal arm of the bell- crank and paid out as the shaft deepens . The weight of the wire in the shaft is counterbalanced by weights hung on a third

- e . 6 arm of the bell crank or otherwise arrang d No . gal

- 0- ft v anized iron wire is good for a 50 . shaft ; for greater

- - depth i in. strand is better . The bell crank may be con ’ - v eniently placed in the head man s shanty . the Regular stopping places for the bucket , such as ” steady , are marked by the engineer by tying cotton cord around the rope . It is to enable him to see these marks more readily that the lever stand should be placed behind the engine . 2 00 ft. After a shaft has reached a depth of about , it becomes necessary to steady the bucket very carefully PLANT REQUIRED 25

i i i i i before ho st ng , to prevent its str k ng the t mber . With a s common rope the bucket al o rotates rapidly on a long hoist . “ ” To ff ui avoid these e ects , g des and a billy , or dummy , 4 Fig , are installed . The billy is a light frame of wood or r i iron composed of two up ight parts engag ng the guides , and a — h i cross bar, t rough the middle of wh ch the rope passes. i ff 4 It is carr ed by a bu er, clamped to the rope or 5 ft. above s the chain ocket . The guides usually are terminated at m ni the bottom of the last placed section of per anent li ng, f s h and bu fer block stop the billy at t is point , the rope running through the hole in the cross- piece as the bucket i s . i de cends nto the bottom If the b lly is made of wood, this hole should be lined with iron to prevent cut i r t ng . Old ubber pump valves make good buffers on the rope and on the stop blocks . Both wooden and wire rope guides are used for the

billy , but even where the FI G. 4 . permanent guide timbers

are available , rope is to be preferred . It can not only be

placed more quickly and cheaply than timber, but it is s is a afer . With timber there likelihood of the billy stick

ing, and then jarring loose and falling on the bucket ; with A wire rope this danger is avoided . t a shaft in Western

Pennsylvania several years ago , the billy, after sticking

on some ice on the wooden guides , fell and killed four men . The use of a billy prevents any rotation of the bucket

above the bottom of the guides , but below them the rotation i t n iﬁ difﬁ cult — seems n e s ed . To obviate this y, non rotating

ropes have been devised . One form consists of a core and two layers of 7 - wire strands wound right—handed and left w be handed , respectively . The ires in the strands may

— fulﬁ l wound either common or lang lay. These ropes their d purpose (in fact are speciﬁ e in some recent contracts) , but 26 PRACTICAL SHAFT SINKING

ar rt u is i ss do not we pa ic larly well . It mpo ible to use an o i a - k s i rd n ry lang lay rope for sin ing a it will entirely untw st . n r - w r r i Seco day po e P oducers. The most mportant of the secondary-power producers around the sinking plant i is air . has e the compressor As yet , electric ty b en unable to compete with steamor compressed air as a motive power for rock drills or sinking pumps ; for underground work air has incidental advantages over electricity in that it assists i s ventilation and cannot ign te explosive ga es . The simple straight- line air compressor is the favorite ﬁ r s for sinking . It is made by a number of m; the Ingersoll ’ 1 - l -i ir in n. a . m O Rand Co s sizes range from 0 . stea X i

1 - -i -i - in 24 n. air 3 . 2 i 24 n. 0 X n. stroke to steam x i X 1 f i 77 122 t. w 3 . stroke , th capacities of and cu of free air per mi is fﬁ i nt i l u . e c e n te , respectively It more mechan cal y l i e than most smal eng nes , and is wonderfully dependabl

1 6 1 -in a with reasonable care . The X 6} X 1 8 . size is convenient one for a pair of shafts ; it has a capacity of 500 ft i . cu . . and will read ly operate four drills and a small pump

- — A straight line compressor with a two stage air end , i the . 1 Fig , is made , which , accord ng to the statements of

s . a manufacturer , ought to be a good investment With

45 - steam consumption of lbs . per indicated horse power at

- off half cut , the simple compressor has , for each indicated

- ft i 5 . . horse power , a capacity of cu of free air per m nute 1 compressed to 00 lbs . With the same steam consumption

- the two stage compressor will deliver 1 5 per cent . more air . ft For 500 cu . . free air per minute , the saving of the two stage over the simple type will therefore amount to 1 5 per 1 f 4 1 . . 5 675 5 0 t. 50 cent . X 5 X 0 cu X lbs . steam or lbs coal per hour . With the compressor operating to capacity twenty hours per day , six days a week , the saving in three 2 5 5 . months , with coal at per ton , would thus be $ This is somewhat more than the difference in cost of the two machines . n s O tunnels and similar work , where a number of shaft and headings are to be driven along a line , it is economical

28 PRACTICAL SHAFT SINKING

rr use l nd hi - i wa ant the of a smal a delicate gh speed eng ne . A cheap and satisfactory light plant is formed by an 1 1 } i - n 2 r c 1 in. k lowatt generator, belt o nected to an 8 X , ho i zontal i - i e , med um speed, automatic eng ne . The voltag

IG - s e t F . 5 . Sinking Head frame howing Dumping Arrangem n should not be higher than 220; even 1 10 will give quite a severe shock to a man who is soaking wet .

The outside wiring calls for no especial comment . In the shaft , however , very thorough insulation is required k on account of the constant fall of water . In sin ing, the bottom lights must be raised before every shot , and it is PLANT REQUIRED 29 most convenient to suspend them by their own wire froma 4 reel . The reel may be kept on top of the shaft for 00 or f 5 t. 00 of sinking, and then moved down to reduce the weight i of hanging wire . A su table reel may be cheaply built of wood by a carpenter . The two wires should wind on sepa so rate drums on the same shaft , that they will hang entirely

. e clear of each other If a wooden shaft is us d , the journals may be covered with copper strips , and made to serve as collecting rings . Six 1 6 candle—power bulbs arranged as a cluster will light i the shaft bottom . They should be set nwaterproof sockets and protected against breakage by wire screens . An i wi inverted d shpan hung above the cluster, th the wires i i dl i pass ng through a hole in the m d e, will shed fall ng water, r ﬂ t r and also act as a e ec o . The wires must be heavily i r nsulated where they pass th ough the pan . Of i the aux liary mechanisms of a sinking plant , machine tools and small fans or blowers may be advantageously

ri . motor d ven If a large fan is necessary , it is simpler and safer to drive it direct by a separate engine . A very useful a i h i m ch ne , t at may be either engine or motor dr ven , is a s i —oﬁ to wing ng cut saw for cutting lagging length . Such a machine will pay for itself on a single deep shaft .

B uildings. After the machinery has been selected and a set up , it is necess ry to house it and the men that operate it: The cheap and obvious building materials for temporary

- 1 i . work are n. boards and tar paper They are also highly inﬂammable di , and on that account should be used with s cretion when it comes to covering valuable machinery . It is surprising how completely the burning of a board shanty i - will wreck an engine inside t. Twenty two gage corru gated iron can be bought and erected nearly as cheaply as boards and paper, and should at least be used for covering the compressors and engines . In cold weather it is hard to i heat a corrugated iron build ng, hence boards are preferable for shifting shanties , etc . The buildings needed around a sinking shaft are : Boiler 30 PRACTICAL SHAFT SINKING house; compressor and dynamo house; engine house; shift shanty ; blacksmith and machine shop ; powder house; oil house; powder thawing house; othee and tool house . The sizes and styles of these depend on the size of the H j ob and the desires of the man who is running it. e may

c s so . on olidate or omit me of them In general , however, they all have different functions and should be separate . i s a s hin If the bo ler are under the s me roof a the mac ery , they should be divided from it by a tight partition to keep r s shif cinders and dirt out of the bea ing . The t shanty all should be adjacent to the shaft, large enough for the men

Sides of 8 x “!

s FIG . 6 . Detail of Sinking Bucket

e on the shift to change their clothes at once , and should hav i plenty of pegs for drying clothes , and a good stove or rad ator . The powder house and the oil house should be separated from each other and the former placed some distance from i th the job . They should be only large enough to conta n e i stocks of dynam te and oil actually needed , and should be built of iron to lessen the risk of ﬁ re and lighting .

Caps and exploders should never be stored with dynamite . The powder thawing house is preferably a box or closet that mi will hold three or four boxes of dyna te , and is heated by r steam coils . It should be so const ucted that loose sticks of powder cannot come in contact with the hot pipes.

Thawing boxes covered with manure are sometimes used, but are not safe , as manure is liable to spontaneous com bustion . PLANT REQUIRED 3 1

The blacksmith and machine shop should contain a forge ﬁ tted with bellows or hand blower as well as a blast air in connection to the l e , benches with common and pipe

- V ises , a grindstone , a small drill press , and , on a good sized

ob r i . j , a pipe cutting and th ead ng machine The small tools - ni should comprise blacksmith and drill sharpe ng tools , pipe i dies and cutters , bolt d es and taps , a ratchet drill , hacksaw , i hammers , monkey and pipe wrenches , cha n tongs, etc . A good assortment of miscellaneous pipe ﬁ ttings and repairs should be kept hand .

- k FIG . 7 . Double Spur Gear Reversible lin Motion Lidgerwood Hoist The contents of the tool room also depend on the size of th e end . job , but a good equipment saves money in the The following articles are either necessary or very useful : G ﬂat ood assortment of round and blacksmith iron , assorted nuts and washers , packing for engine and compressor glands and pumps , gasket , waste , oil cans, torches, crosscut saw , crowbars , striking hammers , picks and shovels , assorted n ails , manila rope and blocks , cant hooks , lever jacks , etc . The general layout of the job depends so largely on local 32' PRACTICAL SHAFT SINKING

i has a recommendations . The location of the bo lers alre dy i d been discussed if a railroad sid ng lea s to the shaft , it is i it so well to place the line of bo lers parallel to , that coal can The be unloaded directly into bunkers. storage and sub The sequent handling of timber must also be considered . temporary buildings should be so located that they will not be put into a hole by the encroachment of the dump the position of the dump itself must be considered with relation i to the drainage of the surrounding ground . The sink ng i o h as s eciﬁ ed eng ne , b ilers , and mac inery ( is usually p ) should not interfere with the erection of the permanent

mi . ai ning plant Lastly, it may be ag n stated that too much attention cannot be given to the piping system all s dr a . over the job regards tightness , ainage, and insulation

Cost. The cost of a plant for a single shaft , assuming f 500 t. inﬂow a depth of about and a moderate of water, 40 i say 30 or gallons a m nute, is as follows Sinking engine Two 80 horse-power boilers and setting Pipe and auxiliaries 1 50 horse-power heater

- 14 inch compressor . Three drills and steel Shaft bar and clamps

Head-frame Two buckets

Buildings Dump cars and rail 1 0 s Electric plant , kilowatt Two pumps Small tools Total

ﬁ ures These g are based on the cost of new machinery, and are large enough to include the necessary accessories . The cost of erecting and dismantling such a plant will be 1 000 2000 i from $ to $ , depend ng on location , labor condi tions, etc . CHAPTER III

SI NKING THROUGH SURFACE Som‘ GROUND WOODEN

L SS S OF STEEL SHEETING STEE SHEETING CAI ON , o on OR CONCRETE . W ,

SINK ING THROUGH SURFACE I N most localities a certain amount of soil or soft ground i overl es the ledge rock . Its depth varies from nothing to e its is as hundreds or even a thousand fe t , and nature varied as i that of the rocks which it covers . The shaft s nker is i chiefl in its e hi i s nterested y consist ncy, w ch determ ne whether the penetration of the surface will be the easiest or h the most arduous and expensive part of is job . There is no hard and fast line of demarcation between fi rmground and running ground ; every degree of hardness or so ftness can be found from boulder clay to river silt, di i i is firm but or narily n sink ng, ground considered when the e and so t xcavation can be carried ahead of the support , f when the support must be driven ahead of the excavation . fi rst cl i di a In the assifi cat on are included boulder clay, or n ry r dry blue or yellow clay, cemented or clayey g avel and most loam soil loose sand and gravel and silt come under the s econd . The amount of water in the ground has a very great ' efi ect fi rmness i on its , as is shown by the cav ng of excava i s i r t on after a ra n storm ; conversely, soft wet g ound may be made comparatively fi rmby removing the water . The commonest application of this principle is the use of com pressed air for driving quicksand tunnels without the use of ashield . In this case the water is forced back away from e the face into the surrounding ground , and timb ring opera 33 34 PRACTICAL SHAFT SINKING

i i l tions can be performed read ly, wh ch wou d be utterly impossible if the water were allowed to ﬂow into the bore of the tunnel . i as ri w G . A trench in qu cksand recently d ven at ary, Ind , with very great success ; here the water was drained in advance of the excavation through a number of small per forated pipes driven into the ground and connected at the

Ti 8 . FIG . Hanging mbers in Firm Earth u i w i s pper ends to the suct on side of a pump . The r ter know of no case in which quicksand has been drained in advance of the excavation of a sinking shaft by driving small suction it the pipes into , but in view of the success of the plan in trench instanced above , he sees no reason why it could not be worked out for a shaft . Compressed air is extensively used for sinking bridge piers and other caissons through soft ground ; the applica i tion of th s process to shafts will be considered later .

36 PRACTICAL SHAFT SINKING

are i s beyond the lagging at each end, la d acro s the shaft on the surface and their ends are supported by blocking them

. se i solidly against the ground , Fig . 8 The ts of t mber are i i rs then hung from these bear ng t mbe by heavy rods , and

4 5 ft. s sinking is resumed . As soon as or of ground i is i removed , another set placed on the bottom , hung w th h i is w in rods to t eset above, and the lagg ng orked back of them in pieces just long enough to bear on both sets . The i i process is then repeated . Bear ng t mbers are usually

' buntons placed over the end plates and over each row of , and punch blocks are set at the corners and under the ends 2 in i 4 ft n ns 1 1 . . b t . 0 of all u o X t mber sets, spaced center to center and braced so that the longest span will not exceed ﬁ rmar 60 7 ft 12 ft. u 0 . , will safely s pport e th for a depth of or The weight of the timbers is partly carried by the friction i of the earth against the lagging, and the hang ng bolts are not subjected to great stress ; they may sometimes be em i tirely omitted . A ledge of earth is in th s case left under i the bottom set , and the m ddle of the shaft excavated ; inclined posts are then wedged between the shaft bottom and the timbers and the ledge removed . It is generally

- in. 1 l i . Exca safer to use % or i hang ng bolts, however i ns i v at o of th s character can be done for a total labor cost, i 2 including the placing of t mber, of to $ per cubic yard .

As the softness of the ground increases , the distance between sets is decreased . Sometimes the lagging is omitted and the lower set worked in immediately under the one above . The consideration of this plan properly belongs under soft ground work .

SOFT GROUND

Wooden Sheeting. When ground is so soft that it will not stand vertically at all, it becomes necessary to support it in advance of the excavation . The commonest method of doing this in any kind of pit is to enclose the area to be

' coﬁ er dug out with a of sheet piling, driven by hand or

. 9 i power, Fig , and to brace the ins de of the coﬁ er as the SINKI NG THROUGH SURFACE 37

i m . s s ater al is removed In tarting a shaft , two set of timber, f 5 t. u one or so above the other , are set up as a g ide frame , dri and the sheeting ven around them . The top soil is usually ﬁ rmenough to enable these sets to be placed below

i . s the surface , but th s is not, of course , essential If the set i are placed above the surface , outs de waling pieces are bolted through the sheeting at the top set in order to hold i in the top of the sheet ng line .

FIG . 9 . Successive Courses of Sheeting

In dry sand or other loose ground that does not contain r much water , the sheeting is d iven as the excavation pro resses g , and the points of the piles are kept only slightly

- n 1 2 1 6 ft in . below the bottom . Two inch pla ks to lengths are commonly used in this case and are driven by hand with

heavy wooden mauls . The heads should have beveled

e . 10 edg s to prevent splitting , Fig , and for hard driving , or

— i . with soft wood , a plate ron cap may be used to advantage B i r y thus protecting the r heads , the planks can be d iven to their full length ; a second course of sheeting is then driven ﬁ rst inside the timbering of the course, and so on until the ir i li i h s requ ed depth is reached . The econom cal mt for t i 38 PRACTICAL SHAFT SINKING

i i m 50 ft. t i ethod , however, is about , as necess tates start ng the shaft much larger than the minimum required size ; some additional allowance must be made on every course for possible distortion and for inward bending of the sheeting 1 1 ft. 0 i L t us s 50 0 n. at the points. e as ume of surface , X

- 2 2 t 1 4 f . i 2 in. a timber , and lagging , and a shaft X w th

— 4 f . e i l t. concrete curb wall Four courses of she ting w l be f 2 i 4 i 4 n. i 2 . n 0 t . 3 ft required , the last X . outs de , its wall Al i . i plates to be bur ed in the concrete lowing 6 n. all i or around each t me for distortion squeezing , the third set in s 26 4 . i 3 ft. 2 ft. 4 n. 5 4 . will be 3 X , the econd in X

IG 1 IG . 1 1 F . 0 F

i 2 n. ﬁ t i . 3 ft. 4 rs 9 ft 4 in 41 f n t. 4 8 , and the . . X The total i th r excavation w ll thus be 40 per cent . in excess of that eo eti i cally requ red for the curb wall . Any additional depth necessitating another course of sheeting will increase the u i ui percentage of seless excavation , and w ll req re a larger quantity of heavy timber . Wh en many light sheet piles are to be driven , the work can be done more cheaply with some form of power driver

. i than with mauls A driver like an enlarged rock dr ll , 12 i . m Fig , has been dev sed for this purpose , and a co mon drill ﬁ tted with a hammer instead of a bit will drive light i sheeting satisfactorily . Either machine s suspended with blocks and falls from a trolley or tripod over the line of sheeting. SINKING THROUGH SURFACE 39

i Steel Sheeting. In qu cksand or other wet running m i ground , sheeting ust have jo nts that are almost water d i tight , and as it is impossible to r ve common plank close

' enough to make a satisfactory coﬁ er in such material with i out caulk ng , some form of interlocking piling should be s Wakeﬁ eld used . Formerly tongued and grooved , plined , or 1 . 1 i piling , Fig , were the only forms ava lable , but now they

2 t- e I . 1 F G . Shee pil Driver have been superseded for difﬁ cult work by the interlocking s l r teel sheet pile . A s ight obst uction will cause wooden im piling to separate at the bottom , whereas it is almost

possible to pull the steel piles apart . Steel piles , moreover,

can be more easily driven , will penetrate most obstructions ,

and can be readily pulled and redriven . There are a dozen

types on the market , each with its advocates , but the sim

lest Cc. p shapes are those rolled by the Carnegie Steel ,

a 1 . 13 . . b Cc. ( ) Fig 3 , and by the Lackawanna Steel , ( ) Fig 40 PRACTICAL SHAFT SI NKI NG

n s i Both are stro g and at sfactory and, though not water t il so in ﬁ rs dri . tight when ven , w l soon become most ground An additional advantage that steel piles possess is that f they can be obtained in lengths up to 60 t. and can be h completely driven before excavation is started . W en the r a ground is ve y bad , they should be m de to reach rock so as i in i to prevent mater al from ﬂow g under the r points . In n 2 ft o 6 2 f 6 in in 7 . e case a hole 3 X 7 t. . plan and deep was needed for a furnace pit; the material was soft quicksand

. i i 48 ft and rock lay at an unknown depth Steel sheet p l ng . long was obtained and successfully driven entirely around l f . the pit and followed down 4 t be ow the surface . The first as d 20 ft. of sand was e ily remove , but as the depth increased, sand began to flow in under the piling and gradually bent i terrifi c their points nward , throwing a strain on the lowest fi nall set of timber . A complete wreck was y prevented by fi lling the hole with sacks of concrete which sank into the his sand and supported the lower end of the piling . T en i abled the des red depth to be reached , but it would have been practically impossible to reach rock if the hole had been intended for a shaft . i h Steel p les and eavy wooden sheet piles must , of course, i i i d i be dr ven by machinery . Wh le a discussion of p le r ving would be out of place in an article on shafts , it may be said ’ e that , in the writer s opinion , a steam hammer is preferabl r i r to a d op hammer for sheet pil ng , whether used in regula or suspended leads . Sometimes a water jet is necessary ; with a jet piles can be easily sunk by the weight of the ham mer through sands into which they cannot be driven at all .

' The chief trouble in driving a steel- pile coﬁ eris in making a good closure . Sometimes the last pile exactly ﬁ lls the gap , but more often a lap joint is made which is caulked with hay or junk . With care a good joint can be made in this ff way . Steel piling in short lengths is used for cutting o thin strata of quicksand encountered some distance below the surface . In this case the piles are locked together all SINKING THROUGH SURFACE 41

i 2 f the way around and each is dr ven only or 3 t. at a time u ntil all reach the rock . r r st d Steel piling can be d iven th ough logs , rata of cemente ni rs gravel , etc . , but in ground contai ng large hard boulde At some other method must be used . a quicksand shaft in

Michigan , boulders were encountered , but steel piles were driven until they had apparently reached the desired depth . h cofi r T e e , however , could not be excavated , as the sand in some way flowed in as fast as it was removed . Com air fi nall pressed was y applied , and when the points of the piles were reached , they were found to be torn apart by the i boulders . Several piles , bent through a full half c rcle, were pointing up the shaft .

F . 1 m3 . Sheet Steel Piling

l s Forepoling. Forepo ing was formerly used for shaft in 100 ft soft ground of any nature , and depths of . have been r eached in the worst kind of material . Under such condi i t ons forepoling is very slow and expensive , and although it r d has been largely , if not entirely, supe sede by the steel sheet pile or caisson methods , some discussion of it is of l t- interest . Forepo ing is still widely used for sof ground n tun els . In starting a shaft which is to be forepoled through difﬁ cult r ground , strong trusses are used for bearing timbe s and the ring timbers are suspended from them by heavy s 1 . i . 4 bolts The trusses pan the shaft , Fig , and the r ends are supported by broad cribs or piers set well back from l the edge of the shaft . They are bui t strong enough to carry the weight of all the surface timbering and also of

- - is . the head frame , if one used After the head frame , or d errick , is ready , digging is started and the sides of the shaft are supported by short piles or poling boards driven on a 42 PRACTICAL SHAFT SINKING slant so that they bear against the outer face of the bottom set of timbers and the inner face of the one above . The poling boards are made twice as long as the distance s or so between the ets ( longer) , when one course is driven h ’ ome , enough ground can be dug out to enable another set

of e . s timb rs to be placed The wor e the ground , the longer must the poling boards be made to prevent it ﬂowing under them . The most troublesome places are the corners where the boards are divergent , and the spaces back of the buntons where a board is necessarily omitted . These openings are closed by short transverse boards placed as the excavation proceeds . 4 f 0 t. After a depth of about has been reached , the pressure of running ground becomes so great that single se ts of timber, spaced so the poling boards can be driven i t. i between them , will not support Two or more t mbers must then be placed skin to skin to form the wall and end plates , and as the depth increases the spacing of these compound sets must be reduced until the poling boards have to be driven nearly horizontal , and therefore fail to prevent the ground from rising in the shaft . This is where r troubles with the forepoling method really begin . Eve y inrush of material causes a settlement of the ground around the r r shaft , th ows the shaft itself out of line , and puts ve y i great stresses on the timbers and the hang ng bolts . In some cases heavy timbers driven with a ram have been used for poling boards . They were thus driven deep s sufﬁ enough , and the successive courses were eparated i ntl c e ri . y, to permit very heavy ng timbers Among the other plans that have been devised to keep the bottom down may be mentioned : Drainage of the ground ahead of the excavation by meamns of a perforated iron drum , jacked down and used as a su p for pump suctions . A short stoppage of the pumps will allow the ground to become saturated again and start a run s r ni , and besides it is very hard to keep pump un ng steadily with sandy water .

44 PRACTICAL SHAFT SINKI NG

ff caisson to the rock . It thus a ords a decided contrast to ar b i n the Pettibone shaft ne y, wh ch , su k by forepoling , took ﬁ ures n eight years . Cost g are unobtai able but seem unnec L D . . W. i 5 f t. 4 essary . The walls of the , ca sson are in. i n. 2 ft. 8 thick at the bottom , at the top , and are plumb on nf d ss- s b n the outside . Two ree orce cro walls erve as u tons and also support the side walls . Several rectangular caissons have been sunk along the ﬂats P Monongahela River in the above Brownsville , a.

The ground is not very bad , but contains enough soft clay di c t and quicksand to make timbering very fﬁ ul . Two of h f these were coal shafts and were sunk t rough 50 t. of sur

— face in two months in the winter of 1 908 09 .

Circular Caissons. A circular caisson was sunk in the 2 autunmof 1 908 for Shaft No . on the Rondout Siphon

. ft of the Catskill Aqueduct The surface was about 60 .

ft . i 6 . th ck , of which was sandy loam The balance was a n wet material that resembled blue clay whe dried out , but which in the ground was completely saturated . It ﬂowed

wa . slowly like cold molasses, and svery sticky Overlying the rock and entirely surrounded by the muck were quantities hi of hard boulders of all sizes , w ch had to be blasted from i under the cutting edge of the ca sson . The combination made as difﬁ cult ground to sink through as can well be conceived .

- The shaft desired was a three compartment shaft , 1 2 f s 2 t. 0 X outside the timber , with two hoistways . The 1 i 2 ft. 1 ca sson was made inside diameter, Fig . 5, giving ample room for the hoistways and a ladderway ; the area for air is of course in excess of that afforded by the rectangular shaft . This caisson was built and sunk to rock in two s il months , and a description of the method u ed for it w l give a good idea of the process in general :

i 3 - in It was decided that a ca sson with 0 . walls would be strong enough and heavy enough to sink to rock , and a steel 2 f 6 t. shoe or cutting edge in outside diameter was obtained . was 2 in This shoe formed of two 5 X 0 . plates riveted SINKING THROUGH SURFACE 45 together at the bottom and ﬂared at the top to include the s lower part of the concrete wall . It wa anchored to the

i - in f . concrete by about eighty i . X 8 t countersunk head bolts .

1 4 . FIG . Forepoling

was The shaft site leveled , the shoe assembled upon short s planks laid on the ground , and form for the concrete were

i 2- i n. started . The forms were bu lt of vertical lagging in

— i \ 4 ft. 4 lengths, supported ins de and out by rings of X 3 in.

- . i angles tied together by in. rods F ve feet of 1 : 2 : 5 con crete was placed and allowed to set for a week to obviate the possibility of settlement cracks above the cutting edge ; 1 ft 0 . more was then placed and , as soon as it had hardened sufﬁ cientl rmi i y to pe t of the forms be ng removed , sinking

was commenced . The mud was loaded into shaft buckets 46 PRACTICAL SHAFT SINKING by men standing upon plank rafts and was hoisted with a i derrick . Somet mes the mud had to be bailed with water d buckets , but usually shovels could be use . ﬁrs 1 When the top of the t 5 ft. of concrete reached the

1 0 ft. an ground level , more were added d excavation com menced again . Thus far the cutting edge had been very x little in advance of the e cavation , but at this point the cais

r 7 ft. 12 son suddenly d opped and the mud inside rose ft. The cutting edge was seen no more until it had almost

r 20 ft. reached rock . After the d op of concrete were added before excavation was started . Before this had been sunk to ground level , a stratum of very soft mud was encountered which ran in under the shoe and caused the surface to cave i so on the side next the derr ck . The cais n gradually leaned i 2 ft toward the cav ng ground until it was nearly . out of 1 ft i 0 . plumb . Sink ng was then stopped , of concrete added , a trench dug through the 6 ft. of surface clay on the high i s i k ai s de of the cais on , and the d rt ban ed ag nst the caisson

- i i a over the cave n. When sink ng w s started the caisson

. i began to right itself It soon stopped mov ng , how and ever, the cutting edge was found to be resting on hi large boulders w ch had to be broken with dynamite . In the meantime the mud ran in almost as fast as it could i i . be ho sted out , and the cav ng continued When the f i 6 t. cutting edge was with n about of rock, the caisson literally stuck in the mud and refused to move even when the boulders were blasted out all around . A heavy timber platform was then built on top of the concrete and loaded 200 i with tons of clay . As the ca sson still stuck , the sur rounding mud was agitated by blowing compressed air into

l -i i v it through i n. p pes which had pre iously been built i l - in nto the wall ; a é . pipe was also used as a jet and worked i down to its full length on the outs de . This was done over and over again all the way around . After a few hours the drum started to sink and reached rock without further

trouble . The trouble in this case was due to the great stickiness SINKING THROUGH SURFACE 47

i 6 in. n s of the mud . An additional thickness of the wall would have probably caused the caisson to sink without

- the delay . As it was , only forty eight days elapsed from erection of the shoe to the commencement of rock excava

ft. tion, an average progress of per day .

‘ Verﬂca/

' Remforcement

B bf e.

1 FIG . 5 . Circular Concrete Caisson

Fi 1 . 6 m g shows the shoe and the lower part of the for , 1 7 h . t e Fig shows derrick, mixer, and general layout , and 1 Fig . 8 shows the dump composed of mud spread out over an acre or more of ground . All caissons should have some vertical reenforcement , so that if the upper part sticks the lower part cannot drop i away from t. The absence of this has caused several wrecks . 48 PRACTICAL SHAFT SINKING

Steel shoes are only necessary in ground containing d boulders . A concrete cutting e ge properly reenforced i is strong enough to penetrate sand or clay w th safety . A number of points must be considered in deciding whether to use a rectangular or a circular caisson in a given i is i n shaft . The c rcular shape eas er to build and si k , and , i i n owing to arch act on , th n er walls can be used . No horizon

‘ r é nforc ment - tal e e or cross braces are needed , and therefore

IG . 16 . e e r e e t ass F Sho , Low r Pa t of Form , and R inforc men , Rondout C i on

rectan u a grab bucket can be used to advantage . The g i lar shape , on the other hand , requires less excavat on, and the walls of any caisson must be made thicker than are n eeded for strength to give weight for sinking . In general it is probable that the circular shape is better for a one or

- - two compartment shaft , and for a three compartment shaft in very bad ground the rectangular for a three- compart in r ment shaft ordina y soft ground . For long shafts , a rectangular caisson is a necessity . An allowance should always be made for a possible 2 ft tilt from the vertical that may amount to from 1 8 ih . to . , SINKING THROUGH SURFACE 49

e in s either by batt r g or stepping the wall on the inside, or i iss e n i by mak ng the ca on larg r tha the neat size requ red . In a rectangular caisson the side walls should be braced with i i r bunt n temporary struts wh le s nking , and the pe manent o s or cross-walls placed after it has reached its ﬁ nal bearing on the rock it may otherwise be impossible to line the guides

i i The relative costs of piling, forepol ng, and ca sson are inﬂuenced by local conditions and by the type of shaft i des red . For instance , a permanent shaft , such as the

L . D . , . W shaft at Wilkesbarre, must have a masonry

FIG . 17 Derrick and Head Works Rondout Caisson

i i l n ng through the surface anyhow , and it is therefore not fair to charge against the excavation the cost of the concrete in . on the caisson In a temporary shaft , the other hand , the excess of the cost of the caisson over the cost of a timber ini s l ng mu t be charged against the excavation . The writer believes, nevertheless , that wherever the ground is not ﬁ rmenough to support itself for one set in advance of the i t mber lining , a caisson is safest and cheapest in the long run . A possible exception may be made to this statement in the case of a moderate depth of very wet ground where the work is done by a contractor who owns the equipment for driving steel piles and can recover them after the masonry ini use l ng is completed and them on other work . 50 PRACTICAL SHAFT SINKING

The costs given below should be fairly representative for the diﬁ erent methods of work : 14 2 f f 0 t. u 6 . 1 . Shaft excavated X % thro gh t of soil 1 4 ft. . s and of quicksand , not very wet Sides upported by

- ﬁ v 2 in. oak sheeting driven by mauls and braced by e sets 1 2 of 10 X in. timber .

IG . 18 . t ss i t a F Dump, Rondou Cai on , Show ng Flowing Nature of Ma eri l

Labor

6600 e B . M . 30 Lumber, fe t at $ c Ere tion of derrick, etc Superintendence Sundry Coal and pumping Total

2 2 2 i 45 ft. 1 f n. . 3 Shaft excavated x 0 t. through of in 1 0 10 . clay and gravel . Sides supported by sets of X

- l - w i . 4 f . pine timber spaced % t. centers and hung from top g n lagging Labor 240 25 Lumber, feet per foot at $ s 1 5 s er Bolt , pound p foot at E - rection of head frame , etc . Superintendence Power Sundry Total

52 PRACTICAL SHAFT SINKING

Running mud may be checked long enough to allow it to harden by’ caulking under the shoe with blocks of wood i and old sacks . Streams of water and quicksand requ re a i wedging curb of some kind . The Engl sh method of sealing 1 . 9 tubbing to rock can be applied ; this may be done , Fig , by cutting out the rock under the shoe until the cutting ri ll edge attains a fair bea ng a around , then driving numerous wooden wedges into the crack until the water is blocked 2 the . . 0 back Another plan , Fig , is to lead the water to center of the shaft through pipes set opposite the main

fal m/

F 1 . 2 FIG . 9 m0

is feeders . A brick or concrete wall then built from the i rock to the caisson , surround ng the pipes and forcing all h the water through them . W en this masonry has set hard enough to stand the water pressure , the pipes are plugged . Several small pipes should also be built into the wall so that grout can be pumped back of it to take up small leaks . in nc With either method great care is necessary, comme ing the rock excavation , to avoid opening up a new leak .

Sometimes the quantity of water may be so great v that it ff cannot be shut o as described . If it is anticipated that i the ground will be very wet , prov sion should be made in the design of the caisson for the use of compressed air s hi a described below . T s provision was made in the SINKING THROUGH SURFACE

D L W. ss G . FI 21 . t . . S eel Shoe for , Cai on

. r W G 22 L. FI . e t f . ss n o D . Sho and Fo m for Bot m o , Cai o 54 PRACTICAL SHAFT SINKING

’ ir L . a . . W D , caisson referred to above, although was not used .

i . . D L W. The follow ng notes on , caisson , taken from the En ineerin News 28 1 08 9 . g g for September , , are of interest nk In si ing the shaft , after the surface had been removed with plows and scrapers and the bottom of the excavation

1 2 . . s F . W L. s 0 3 eenf D . Showing R orcement for , Concrete Cai on

21 a a . w s m de perfectly level , a steel shoe , shown in Fig , placed on the bottom of the excavation . This was made of

-in 24 i 2 in e n. 3 . h . plate , was wide , igh , and re nforced , as i shown , with riveted angles . The shelf wh ch formed the n base for the concrete was placed 8 i . above the toe of the vertical plate . The outside dimensions of the cutting shoe 28 f i . were X 59 t. 5 n The outside form for the concrete was built up flush with the outside edge of the shoe . The SINKING THROUGH SURFACE 55

in d as . 22 inside form at the bottom was incl e shown in Fig , ft being given a batter until the wall was 7 . thick on the t in sides and 5 f . on the ends, when vertical forms were put e i — place . The concrete was re nforced w th tie rods , as shown 2 in Fi . in g 3 , and the walls were decreased thickness in i s in Fi . 25 step , as shown g , unt l they reached a uniform h i 2 0 ft. in. . thickness of 2 ft. 8 at the top W en a he ght of of the concrete wasreached , the bottom forms were removed

2 L. FIG . 4 . D . W. aiss n ea f , C o R dy or Sinking and the concrete caisson then carefully leveled preparatory to sinking . In order to provide for the contingency of having to resort to compressed air in sinking in case the inﬂow of water proved too great to be handled by pumps , arrangements were made to put in an air deck in case of

. Sinkinl rri i necessity g was ca ed on day and n ght , and the excavating gang consisted of a foreman and sixteen men i to each sh ft . The materials were hoisted in buckets by s as in 2 means of derrick , shown Fig . 4 . Just as the caisson

' reached the rock which was being cleaned oﬁ preparatory to putting in the seal , the river rose and the shaft was PRACTICAL SHAFT SINKING

IG . 25 . D L. n s f . W. F Pla and Section o , Caisson Walls SINKING THROUGH SURFACE 57

ﬂooded . It was found impossible to pump it out and the ﬁ ll i shaft was allowed to , to remain full until the r ver had h i subsided . W en the ca sson had sunk to the level of the rock, it was found that a temporary seal would have to be in ri put place du ng the construction of the permanent seal . hi i s T s temporary seal was made of yellow p ne block , 1 2 2 i in i 2 ix- 1 a . . n. F S X size , and wedges , g 6 inch bleeder pipes were left to drain off the water while the seal was being

IG 2 F . 6

in s put place . The pipe were closed after the temporary seal had been completed . To provide a place for the permanent seal it was necessary 2 as i 0 ft. to take out rock for a depth of , so to bu ld a wall i i to carry the caisson . Dur ng the blast ng of this rock great care had to be taken to prevent jarring out the temporary i seal . As the rock was be ng excavated a grout was forced back of the temporary blocking by means of a grout pump 8 with an air pressure of 0 lbs . In order to give a ﬁ rmfooting for the concrete wall the 58 PRACTICAL SHAFT SINKING

se so as rock was reces d to form a toe for the wall , and in order to give good contact between the underpinning wall n ss ss a d the cai on, the lower edge of the cai on was roughened . 2 i Fig . 6 shows the method of mak ng the permanent seal i Th between the caisson and the concrete foundat on . e concrete 0 was put in place as soon as possible after the rock h excavation had been completed , and was of the form s own . d was e Next the ring of concrete placed, and grout was th n pumped into the pipes after the concrete c and d had set . The ﬁ nal wedge of concrete e was laid after the concrete lower down had set and everything below had been made e d thoroughly tight , the edge between and being caulked after the pipe had been grouted ; g is broken stone packed in between a brick dam and the wooden seal ; the brick dam is intended to lead the water to the pipes b.

60 PRACTICAL SHAFT SINKING

The cost of excavation under compressed air is in u general m ch higher than that of open work . In the ﬁ rst s place grab buckets cannot be hoi ted through an air lock , so hand digging is necessary ; second , a special class of high priced laborers must be employed whose wages increase with the depth , while the length of the shifts must be k reduced third , the air loc s applicable to caissons are costly r to build , and as thei construction is covered by patents r i controlled by one or two co porat ons , they are quite costly s n is to rent fourth , the ma o ry of the ca sons must be made very heavy to overcome the upward pressure of the air .

Some grounds , however , can be blown out of the caisson and very little digging is necessary ; in this case excavation i i i is cheap . The l m t for pneumatic sink ng in loose ground

is in 100 ft. , general , below water level , as men cannot stand a pressure greater than that corresponding to this depth . h The deck in a s aft caisson must be removable , and is, i ﬁ tted therefore , made of t mber or steel , into a recess left in the wall . Two openings should be provided , one in the middle for the excavation lock and another for the man

ﬁ - . t i lock American locks are now standardized to a 36 n. circular opening . Small openings must also be made in “ ” the deck for the air connections and the blow pipe . 4 f A man lock consists of a steel cylinder, about t. in

- 8 ft. . diameter and long , with ﬂanged head Eighteen inch openings in the head are ﬁ tted with doors which swing i u downwards in opening, and close aga nst a r bber gasket . e - A small hol in each head , closed by a stop cock inside the the lock , permits the entrance of compressed air from caisson and its escape to the atmosphere . The lower door

- and stop cock being closed , the upper door is opened and several men enter the lock . The upper door is then closed

- from outside , and a lock tender standing inside the lock - h closes the upper and opens the lower stop cock . W en the pressure in the lock has become equal to that in the o l caiss n , he opens the lower door and the men c imb down a SINKING THROUGH SOFT GROUND 61

i ladder to the bottom . In lett ng men out the process is

reversed . The locking through of men is the most precarious part

- of compressed air work . Too quick an application of pres sure causes blocking of the ears ” intolerable pain in the ears and head due to unequal pressure on the two sides of the ear drum and too quick a reduction of pressure

2 7 . n FIG . P eumatic Caisson may cause the bends caisson workers ’ paralysis

always dangerous and sometimes fatal . For pressures 2 can 0 . below lbs , men accustomed to the work be locked through safely in two or three minutes and can work eight hour shifts at higher pressures the locking time must be increased and the length of the shifts decreased . With

45 - - . r ﬁ v e m lbs of air , fo ty inute shifts are worked and -ﬁ twenty v e minutes must be taken in locking through . 62 PRACTICAL SHAFT SINKING

The principle of the excavation lock is the same as that all of the man lock, but the doors and valves are controlled ” s — r from outside . The patented traight th ough lock is in s the best type , fact the only atisfactory type for caisson all i work . Several forms are made , of wh ch require the ” - bucket to be hoisted on a single rope . In the pot lid lock the rope passes through a stuffi ng-box in the middle of hi the upper door, w ch is literally a lid fastened to the lock by six heavy bolts hinged to the lock and engaging slots in the edge of the door . The door is carried by a buffer at the lower end of the rope . When a bucket is lowered into the lock, the upper door is also lowered on to its seat . - i s The lock tender, who stands outs de , rai es the hinge bolts into their slots and tightens the nuts before opening the lower door . In consequence of the continual tightening and loosening of the bolts this lock is rather slow in operation , but it is very simple . Other forms of the straight- through lock have the upper door in two halves which close upon a stuffi ng-box on the st ffi n — f rope . In this way only the u g box is li ted instead of the entire door , and the operation is much quicker . In one type the doors are operated by high- pressure air cylinders . The air pumped into the caisson by the compressors escapes by forcing its way out through the ground close n under the cutti g edge . As it is often necessary to excavate n several feet below the cutting edge to si k the caisson , some provision must be made to remove the water that collects the in depression . This can of course be done with a pump - r to driven by high pressu e air, but it is also possible blow i 4 6 in the water out d rectly . A to . pipe , closed by a stop is r cock at the lower end , led th ough the deck and out over ai the top of the c sson , and a suction hose reaching the

- An sump is attached to the lower side of the stop cock . opening , closed by a small valve or a wooden plug , is made in - - the pipe above the stop cock . When the stop cock is Open the air pressure lifts the water into the pipe ; the small SINKING THROUGH SOFT GROUND 63 valve is opened at the same time and aquantity of air ﬂows i i s it s in and m xes w th the tream of water, decreasing s peciﬁ c gravity until the weight of the whole column of water is ir s i less than the a pres ure . The water s then driven com B pletely out of the caisson . y replacing the valve with a small high—pressure air connection it has been possible to f i 70 t. i 1 raise water out of a ca sson deep w th 3 lbs . of air . Fine sand and silt containing much water can be blown

out through the pipe , and caissons have been sunk without hoisting a bucket of dirt . The use of compressed air makes it very much easier i to seal the caisson to rock . There s of course no trouble i difﬁ cult about keep ng the water out ; the y, is to prevent the i ar from blowing the grout out of the concrete, leaving it porous . One plan is to lay a strip of heavy duck over the i s n th crack , na ling one edge to the cais o and the other to e is on rock . Concrete then laid top of this duck . Some kinds of very wet ground possess considerable i v scosity . In these the pneumatic process can be worked to a greater depth than is theoretically possible by reducing the pressure and blowing out the mud and water that ﬂow in under the cutting edge . One example of this has been f 1 70 t. cited where water was raised with 3 lbs . of air; in England recently several piers were founded at a depth

1 ft 45 . air of 30 . below water level with lbs of pressure . Under such conditions the difference between the hydrostatic pressure and the air pressure is accounted for by internal is friction of the water and the ground . It probable also that the actual hydrostatic head is reduced by the air bubbles which escape under the cutting edge into the sur rounding ground .

THE SHIELD METHOD

i i i i i si Sh elds , s m lar in pr nc ple to those so exten vely used

- for subaqueous soft ground tunnels , have also been applied

- 2 . is to soft ground shafts , Fig . 8 A shoe constructed with a cutting edge slightly larger than the outside of the com 64 PRACTICAL SHAFT SINKING pleted shaft lining ; a vertical lap plate or shield is attached to the outer perimeter of the shoe , and a number of screw (or hydraulic) jacks are set on top of the shoe and inside i is the sh eld plate . The frame of the shoe sometimes made of wood , but steel is preferable . The shield is made of

1 - in f . i 1 in. 3 t 1 to é . plate ron and extends from 8 to above

FIG . Shield Method of Sinking

the top of the shoe proper . The method of operation is as follows : i As soon as the shaft is started , bearing t mbers or tru sses are constructed to hang the lining from as previously described in connection with forepoling . The shoe is assembled in place with jacks screwed down , and the shaft lining is completed from the surface to the heads of the

! 2 4 36 37 47 are d d s o i s. 8 3 F g , , , , and reproduce from the copyrighte in tru tion papers and bound volumes of the International Correspondence Schools t by special permission of the International Tex book Company . SINKING THROUGH SOFT GROUND 65

is i jacks . Excavation then started and the shoe s nks until enough distance is gained to allow another course of lining to be placed beneath the completed section and inside the shield . If the jacks are used to force the shoe down , they must be withdrawn before the course of lining can be placed . The upper edge of the shield must always be kept above i n hi the lower edge of the completed lin ng , and to i sure t s in bad ground it is necessary to hang the shoe from the bearing i timbers with chains and ratchet jacks . Somet mes shoes are made so that the opening can be completely closed with steel plates to prevent an inrush of sand . Tunnels driven with shields are circular and lined with

- 2 f . rings of cast iron segments t. wide Many European i hi shafts are lined th s way , but the American shafts to w ch the shield method has been applied are rectangular and

- - lined with skin to skin timbers or plank laid flat . hi l The chief disadvantage of a s e d , even at a moderate is depth , its liability to hang up on a boulder on one side i while the other side settles , thus wedging tself and throwing hi the shaft out of line . T s tendency can be largely overcome by the proper suspension of the shield , but the depth which can be reached is limited when the ground is soft and wet 1 fl id . u enough to exert u pressure At 00 ft. below gro nd water level , for example , the pressure of wet quicksand will s i 45 . uffi c ent at least be lbs per square inch , to force enough sand and water to flood the shaft through a very small opening . It is impossible to jack a closed shoe down , it displacing the ground under . CHAPTER V

SI NKI NG IN ROCK ARRANGEMENT OF HOLES TooLsAND METHODS USED IN DRILLING Cos'rs AND SPEED

DYNAMITE and the power drill have made solid rock the r r easiest material th ough which to sink a shaft , and p ac tically all American mining shafts are in rock for the greater i part of their depth . As has been sa d before , hand sinking is the cheapest and quickest method although a boring n process has been developed , it is o ly applied where such immense quantities of water are encountered that hand sinking is impossible . i i in Outside of the bor ng process , the mprovements rock s t i it inking have all related o breaking the rock and hoist ng . No practicable mechanical excavator or loader has yet been G e s in n devised . rab buck t that work well soft grou d are in f in . u ailures blasted rock A steam shovel, useful a t nnel , is of course out of the question in the bottom of a sinking shaft . The u Drilling and B lasting. niversal method of shaft s l in inking in rock is to dri l a number of holes the bottom , charge them with dynamite and shoot them, and to load the broken rock by hand into shaft buckets which are then h hoisted out . W en all the loose rock has been removed the process is repeated . As it is very difﬁ cult to drill holes u through loose rock , the broken material m st be all removed before the next round of holes is started . This creates an ifﬁ c lt additional d u y for the mechanical digger , for while a grab might be made to remove most of the loose rock after a blast , hand work would still have to be resorted to to get the bottom ready for drilling .

- Shafts are drilled on the center cut principle . Eight 66

68 PRACTICAL SHAFT SINKING

4 l 0 and 60 per cent . ge atine are the most common strengths used . The number and depth of the holes and the quantities of powder loaded vary so greatly with the size of the shaft l s and the nature of the rock that no genera rule can be stated . The systems actually used at several shafts were as follows : 2 r a 1 3 6 ft. ( ) Shaft X , th ough Western Pennsylvania a : coal me sures Shale , slate , and limestone horizontal 2 4 tr iﬁ ti n . 0 s at ca o ; holes as in Fig 9 ; per cent . gelatine :

Number D ep th

Sump Relievers Benches Total charge

6 . Average gain per cut , feet ain e 1 9 s s 24 e Average g per we k of hift , fe t (no timber) . k s e s 2 s s d 1 Muc ing and drilling imultan ou ; drill u e on bar .

b 14 48 ft. : ( ) Shaft X , through anthracite measures Red sandstone ; stratiﬁ cation horizontal holes as in Fig 30; : 40 per cent . gelatine

Number D ep th I nclination

Sump Relievers Benches

Total charge per round

6 . Average gain per cut , feet 1 e 8 s s 16 e . Average gain per we k of hift , fe t

Mucking and drilling simultaneous; 2 drillsused on 1 bar .

22 1 ft. (0) Shaft 0 X , through quartz conglomerate Sh an nk stratiﬁ cation ( aw gu grit) ; horizontal , but very few bedding planes holes as in Fig . 31 ; 60 per cent . gelatine : SINKING IN ROCK 69

Number D epth I nclination

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Benches Total charge per round

e t 5 fe t . Av rage gain per cu , } e

20 sh ts 22 et . Average gain per week of if , fe and ll n s ult ne us 5 s use n 2 r Mucking dri i g im a o ; drill d o ba s.

The four additional sump holes shown were used on ss account of extra hardne of the rock .

19 ft. 4 in i i . f d 33 t. ( ) Shaft ell pt cal , X , through West i in s: r 4 V rg ia coal measure Ha d gray sandstone ; 0 per cent . 2 z gelatine ; holes as in Fig. 3 ; hori ontal stratiﬁ cation:

Number

Total charge per round

er t 8 eet . Average gain p cu , f 2 s i s 1 a n e 0 8 t . Aver ge gai per we k of h ft , fee r l si t o s 3 dr s se 1 1 h Mucking and d il ing mul ane u ; ill u d on long bar, s ort bar.

e i l 1 7 ft. ( ) Shaft c rcu ar , diameter, through Hamilton and Marcellus shales : Rock distorted ; stratiﬁ cationirregular 3 4 . 3 5 60 holes as in Fig , but about degrees per cent . gelatine

Number D epth I nclination

Total charge per round

er t 5 t . Average gain p cu , 5 fee er ee 1 9 s s 33 . Average gain p w k of hift , feet one s t ont s s 5 s s All drilling on hif , mucking wo hift ; drill u ed on 5 tripods. 70 PRACTICAL SHAFT SINKING

i l h Drillin T ls. r a g oo Hand d illing , once un versa , s been entirely superseded in the United State by compressed- air dr i in difﬁ cult m ill ng , and it is fact to obtain ha mer men .

FI 3 1 . c G . Shaft ( )

l In other countries where labor is cheap , dri ling is still done m “ ” . m r by hand In the co monest ethod , a d ill or jumper

af d I . 2 . FI f e F G 3 3 . a Sh t ( ) G . 3 Sh t ( )

f l -i o n. steel is turned by one man and struck by one

- - 8 1b. u l . 34 a. or two others with , do b e faced hammers, Fig

u use - in ff Americans and E ropeans a 30 . sti handle ; the Southern negro prefers to drive steel with a slightly longer 71 SINKING IN ROCK .

le i l hand wh ttled down until it bends ike a whip . Jumpers i s i r Fi 4 are g ven a ingle cutt ng edge, usually cu ved , g. 0. s Two men should trike each steel wherever practicable , as they can obviously drill twice as fast as a single striker at

- three fourths the cost . As much depends on the man that r tu ns the steel as on the striker , for considerable skill is needed to produce a round , straight hole . Three good

l - in men can drill i . holes in hard sandstone at the rate of

2 f r. t. per hou

FIG . 34a

4 FI . 3 FI G G . 34b

In the Tyrol a system of single- handed drilling has been developed . The driller turns a light steel with one hand 4- l . 4 b . 3 b m . and wields a ham er , Fig , with the other A skil

- t h 3 f . r s ful man can thus drill oles quite apidly, but the hole are too small for regular shaft sinking .

. 38 . For slate , churn drills , Fig , are often used The drill

6 1 2 ft. consists of a straight bar , to long , with a bit at each end An . iron weight is sometimes welded around or forged i 2 f t. nto the drill from one end , thus increasing the weight 72 PRACTICAL SHAFT SINKING

il i i i of the dr l w thout ncreasing its length or d ameter . The r h drill is handled by two or th ee men . When t e weighted drill is used , the hole is started with the short end , and when 2 ft e it hasreached a depth of . the drill is revers d .

FIG . 35 m The reciprocating , compressed air drill is the ost widely ﬁ rs n r c used machine for drilling rock . It was t put i to p a r in M . tical use by Fowle , of Boston , the construction of i w in the Hoosac tunnel , and s nce then has steadily gro n is the popularity . It turned out by the thousands by SINKING IN ROCK 73

- th C . e l . Ingerso l Rand Co , the Sullivan Machinery o , Ki M c ernan C . Drill c , and others, and although each maker r his s in e has certain featu es of own , e pecially the valv i is i the arrangement , the general des gn standard zed and

6 . ar general features are shown in Fig . 3 Piston and rod e i turned out of a single billet of spec al steel , and to the end of the rod the drill steel is rigidly attached by aU—bolt

i - chuck . The cyl nder is made of cast iron and slides longi tudinally in a guide frame (or shell) clamped to the drill i li is mounting . As the drill cuts nto the rock, the cy nder fed forward by a square-thread screw mounted on the “ ” is riﬂe frame . The piston rotated mechanically by a bar and ratchet so that the cutting edge of the bit will not strike f two successive blows in the same spot . This rotative e fect is necessary to drill a round hole . The machine commonly used for shaft sinking has a

- — 2 0 lbs i 6 in. 8 3 in. i cyl nder and a % stroke , weighs , and will l t f dri l down holes in hard rock at the rate of abou 7 t. per

r i in i . hou , ncluding time lost chang ng steels The length of l 2 is 24 in. ft feed , hence the dri ls must be changed every . 2 f t The starter is t. long beyond the shank (the portion of he i 4 f t. drill grasped by the chuck) , and the follow ng steels are , f i F ft t. . i . 6 . 8 . , , etc , respect vely (See g Drill steels u X are usually sharpened with a bit , altho gh bits and i I s stra ght bits are ometimes used . Where a large number of drills are in operation a sharpening machine may be used to advantage . i Two types of valve motion can be obta ned . In the ﬁ rst i , the valve wh ch controls the piston is thrown by a tappet struck by the piston itself the Rand “ Little Giant ” is is an example of this . In the second , a piston valve used which is thrown by a difference in air pressure on the two “ ”

. Th ends The Sullivan Slugger is a drill of this type . e i Sergeant drill is a compromise , having an aux liary valve, i driven by contact w th the piston , which governs the air i a pressure on the ends of the ma n piston v lve . The Slugger s type trikes a hard , uncushioned blow and is adapted to PRACTICAL SHAFT SINKING

76 PRACTICAL SHAFT SINKING

In circular shafts it is difﬁ cult to cover the area to be ’ r in ri s i i it is drilled with a straight ba , and the w ter op n on F i . . 34 best to mount the drills on tripods , g The tripod, while it possesses all the adjustability of other forms of

mrs . mounting , is less rigid and more cu be ome To do good work all loose rock should be removed and the legs set on i is i in s . olid rock Th s feature , however , not object onable a shaft where mucking and drilling are not carried on simul n usl ta eo y.

7 FIG . 3

n in e Before blasti g , the drills and mount gs must of cours

a . d n be hoisted out of the sh ft In England, a rilli g frame use i t o s for in c rcular shaf s has been patented . This c nsist of a ring from which six bars, on which the drills are mounted, project radially . The ring is supported by legs and held

- in rigid by jack screws the ends of the six bars . The chief advantage of this frame is that it is unnecessary to detach all the drills before blasting ; the whole can be hoisted 0 11 the bottom and hung in the shaft without hindering the SINKING IN ROCK 77 78 PRACTICAL SHAFT SINKING passage of the bucket which passes up and down through the is ring . Another advantage of the frame that the manifold is t it dri s n attached o , the ll bei g connected to the manifold is s by short pieces of hose. It thus nece sary to have only one main air hcse hanging in the shaft instead of a small hose for each machine . The best grade of canvas and rubber hose should be r l i un air li used for the d i ls , w re wo d for , and mar n wound ” ose for steam . Steam h should be ordered always for “ ” s i air se i u e . w th steam, as ho w ll not stand heat A sec

- i i l in. 50 ft. s in ll t on of hose long used for operat g each dri . r n i n is l Ope atio . Shaft s nki g usua ly carried on twenty The i four hours a day . nside work is done by three shifts mn n e of worki g eight hours each , the outside by three

— 1 2— 1 2- 8 hour or two hour shifts . The hour outside shift o is o in fi el s — r cust mary the coal d ; elsewhere , the 8 hou shift i for every one is prevalent . Sh fts are usually changed at 1 1 M . 7 . P. s i A. M 3 and and , omet mes an hour later . The men are given twenty minutes for lunch in the middle of hif each s t . in Wages vary with the locality , but general men are paid better for drilling and mucking in a shaft than in any Ou other kind of rock excavation . account of the high w ages paid in America machine drilling is universal, and the shifts are limited to the number of men that can be worked is to the best ad vantage . Speed not attempted at the n i effi cie c . expense of y In South Afr ca , on the other hand , Kaffi r i as labor is cheap , hand drill ng is usual , and many il men are worked as the shafts w l hold . The great depth of the shafts on the Rand makes the i h ghest possible speed desirable , even at an increased cost . In both countries speed is increased without an increase of cost by the payment of a bonus to the sinkers as a reward i for add tional progress . The size of the shifts for any given shaft depends upon the number of drills required and upon the experience and

i ﬁ rs - l n . t abi ity of the si kers obta nable With class men, SINKING IN ROCK 79

hi 1 2 f the men on each s ft at the 3 X 6 t. shaft referred to before as (a) would be as follows : i 8 : 3 Ins de men , hours One shift boss , at $ two drillers,

at two helpers , at six muckers , at 1 2 : i e Outside men , hours One eng ne r ; one head tender ; three car men on dump one ﬁ reman one compressor

man.

G 1 0 : eneral outside , hours One foreman ; one mechanic tw n i o carpenters (o timber) ; one blacksm th and helper .

- The 1 7 ft. circular shaft (e) would require : Drilling shift : One shift boss ﬁ v e drillers ﬁ v e helpers; one extra man . : i i Mucking shifts One sh ft boss ; n ne muckers .

Outside same as shaft (a) . 9 2 In South African shafts, which are usually about X 6

f . 1 s t , when drilling done by hand , each shift consists of one white shift boss and about 35 Kafﬁ r laborers who drill or

muck as may be required . Thorough organization is essential to progress and n his economy . Each man must k ow place and take it

without losing time in getting started . Any condition

that prevents systematic work is fatal to economy . For i inﬂ sufﬁ ient t i nstance an ow of water, c o cause a loss of t me a i i r fter every blast wh le the bottom is be ng pumped d y, will lessen the rate of sinking far more than can be calculated

by adding together the actual delays . air an in Ventilation. Foul d powder smoke the shaft b ottom hinder work almost as much as water . As a rule v ertical shafts ventilate themselves surprisingly well to a f an 4 500 t. i s d epth of 00 to , but at greater depths d somet me at artiﬁ cial much lesser depths , ventilation must be resorted raf s to . The cheapest method , where the natural d t need “ ” li n an air b x only a s ght assista ce , is o , or wooden pipe carried up one compartment of the shaft ; into this box is air x if turned a jet of or steam or the e haust of the pump , i 1 1 2 n. s. one is used . The box is built of X board Another way to help natural ventilation in a rectangular shaft is to 80 PRACTICAL SHAFT SINKING divide the shaft into two compartments with a brattice attached to a row of buntons; one compartment will then l i s n as n . estab ish t elf as a upcast , the other a dow cast If all steam pipes to pumps are kept in one compartment this action is certain to occur . In any case steam pipes should be kept together inone end of the shaft . In deep shafts positive ventilation is best assured by the use of a fan or blower discharging into a large air pipe carried down the shaft and lengthened from time to time 1 — e s. 5 in. a as the shaft de pen A st ndard volume blower, i - sufﬁ cient t eng ne or motor driven , is o ventilate a shaft to

an i ar . r s y ord n y depth The pipe may be made of boa d , i n . canvas , or light , galva ized sheet ron The latter, although m is air- i an is n t ore expensive than wood or canvas, t ght d o t in ur i liable o j y from concuss on . r s in i i i infl Prog e s. Progress shaft s nk ng s uenced by so m f a e any di ferent conditions quality of rock, size and sh p s effi cienc of the shaft , pre ence or absence of water, y of labor and plant that it is very hard to make any general it statements concerning . The best progress records are ma in s in a d e deep rectangular hafts on the Rand , Transva l , s e South Africa . These shafts , as has been aid before , hav i 9 26 ft a sect on about X . in the rock ; work is carried on by three 8-hour shifts 7 days a week ; two compartments are n used for hoisti g , and every man that can be worked is put K ffi r t i . a he nto the shaft labor is not only cheap , but Kaffi r will work under conditions of crowding to which a i i in wh te man will not subm t . The records made several South African shafts are given in Table 1 : the average 1 35 ft the progress is seen to be about . per month , and maximum ft. The progress in this country under normal conditions t s r 0 f . anges from 60 to 8 for rectangular timbered shaft , although v ery much higher Speeds are sometimes reported . The soft shale in the coal fi elds of the Middle Western states i in s seasy to drill and shoot . Good records are made Kansa n An a d Southern Illinois . account of a shaft near Atchison , SINKING IN ROCK 81

li in En neerin . i and Minin umal Kan , pub shed the g g g Jo 26 1 902 i for July , , states that the da ly progress in soft shale ft ﬁ es 7 . ur i was No monthly g were g ven . A good record

1 7-ft i was recently made on a . c rcular shaft in the Hudson River shale (dark blue sandstone and sandy slate) on the

New York Aqueduct . The system of drilling and muck ing used at this shaft is described above under the rock i was quite hard but broke read ly . The average progress ma n in n de here is show the tabulation of America shafts , 2 ’ i 1 . s s ft Table The best month work 77 . No work was i l done on Sundays . The wr ter be ieves this to be a record n s s ! for America haft . The rate of progress in the European circular shafts lies i between the American and the Afr can rate . The rock penetrated is in general softer than that found in this country . Tables 1 and 2 give the dimensions of a number of shafts

s . W i and the progres made in them herever obta nable, the i i nature of the rock penetrated and the cost per foot s g ven . The fi gures were obtained from various articles in the i i v ri i techn cal papers , from the proceed ngs of a ous min ng ’ s institutes , and from the writer s own records ; ome of the South African data were taken from the Deep Level Mines ” A 2 . 90 G . 1 . of the Rand , by Denny, s f r wi s Co t. Cost igu es cover a der range than progres fi s t gure and are harder o get . The cheapest shaft on record is i i the one near Atch son , referred to above, the cost of wh ch , i in it 7 . s as stated , was $ per foot Th s cost stands alone fi awie r ur s Mr. r R glo y as the tabulated g e show . Hen y published in Mines and Mincrals an itemized statement of in r in 1 906 the costs of a shaft sunk West Vi ginia, . These ran as follows

was r k e af Y Since the above w itten , the Brea n ck Sh t on the New ork

T . t . he was r Aqueduct was sunk 1 83 ft . in a mon h rock ha d granite The

. 1 Moodna six s s system used was the same as at No , but drill on tripod ne s i was were used on the drilling shift . O mucking h ft only worked on

Sunday ; no drilling shift . 82 PRACTICAL SHAFT SINKING

' 22 1 1 FT D a 14 FT . m EEP m 80 . Hoxsr S , X ,

s e Labor, inking and timb ring

Superintendence Explosives Coal Timber

The sinking costs of a pair of shafts sunk in Western Pennsylvania a year later were as follows :

' 2 W 1 . u D r r SHA FT 26 m4 2 FT . Ho s , 3 X , EEP

s Labor, inking Plant Superintendence Explosives

Freight

Miscellaneous.

AFT 1 22 u FT D EE AI R H 3 FT . m383 . P S , X ,

Superintendence Explosives

Freight Miscellaneous Total

er i : 50 air Water p m nute Hoist shaft , gallons ; shaft ,

1 20 gallons .

Costs have risen greatly in the last decade , since no sub stantial improvements in methods or machinery have been f s are made to o fset the increase in wages . Contract price

84 PRACTICAL SHAFT SINKING

i as not generally obta nable , most shafts are put down by r r i to p ivate co porations , but prices h gh enough include a good proﬁ t to the contractor eight to ten years ago would

- not cover his costs to day . Twenty—ﬁ v e shafts ranging in depth from 350 to over 1 ft r Y 000 . are required fo the portion of the New ork Aque All v duct now under construction . but two of these ha e

been let by contract , and the bid prices are public p rop a ert . are y The bids, however, unb lanced in every case , and

do not give a fair idea of shaft prices . They range from 175 to 350 $ $ per foot . CHAPTER VI

- E PROCESS . P P THE TH SINKING DRUM MAMMOTH UM . FREEZING PROCESS

- Sinking drumProcess. For sinking through the very great depths of water- bearing sand and clay that exist in some of the German mining districts, a method has been developed that does not require any hand work in the shaft bottom until the lining is completed to rock . The shafts

r - are necessarily ci cular and are lined with cast iron tubbing . s o A heavy masonry cais on , with an inside diameter, s mewhat ﬁ nishe ﬁ rst greater than that of the d shaft desired , is con

50 60 ft. structed and sunk for or , as described in a previous suffi cientl chapter . If the ground beneath the cutting edge is y fi rm ff so , it is leveled o and a foundation ring of ma nry built fl r . o under the tapered part of the wall If not , a concrete o is laid over the bottom (under water if necessary) and the caisson is pumped out . A heavy iron ring projecting inside the face of the wall all around is built into the masonry foundation ring or into a groove cut in the wall above the fl r concrete oo . A second ring, placed near the top of the so n first r cais n , is co nected to the with heavy iron ods, and the space between the rings and around the rods is fi lled i n so r . w th ma n y, forming an inner tube The upper ri g pro jects inside this inner tube and serves as a base for a circle of powerful hydraulic jacks acting downward . A very strong cast- steel shoe or cutting edge with an outside diameter slightly less than the inside diameter of the t tube is hen assembled on the shaft bottom , and rings of cast- iron tubbing bolted together are built up from the top t f has of the shoe o the heads of the jacks . If a concrete loor been laid it is broken up with a huge churn drill, excavation 85 86 PRACTICAL SHAFT SINKING is started with a grab bucket or some other mechanical to i ir digger, and the shoe and tubbing commence s nk of the i n s i own weight . The n er ma onry l ning acts as a guide for i the iron sink ng drum, and must therefore be built with its i axis exactly vertical , correct ng any deviation that may have i i occurred in sinking the ca sson . The rubb ng surface is I - i i usually formed by beams bu lt nto the masonry . i s k are i When mot on cease , the jac s brought nto play and is r the drum forced down , additional ings of tubbing being built up under the heads of the jacks. When the first drum r i can be forced no fa ther, the bottom of the shaft s plugged with concrete , the water is pumped out , and a second sinking t drum built up inside the fi rs . The concrete is broken up as s i to to i before , the jacks h fted so as engage the p of the nner A i i is r . s u s drum, and s nk ng esumed many as fo r drum i 50 ft 8 . have been used, reach ng in one place a depth of The three methods used for excavation under water inside the drum are : i — The Grab B ucket. The act on of a clam shell or

- is n orange peel bucket too well k own to require explanation . n ars n s Either bucket will ha dle co e sa d , gravel, and boulder wi i ﬁne hr to advantage, but ll not reta n wet sand t ough a i o . long hoist , and w ll not dig t ugh clay i The Sack B orer. This is a g gantic auger with the rigid n 4 1 . The stem extending up the ce ter of the shaft , Fig . ﬂan e stem is constructed of heavy g d pipes bolted together, and is terminated at the upper end by a splined section

- which serves as the shaft of a large horizontal worm wheel . n r A hoisting rope, leadi g to a powe ful engine and attached to i to a swivel at the p of the spl ned section , suspends the borer . The stem is turned by an engine acting through the

- W is the worm gear and its orm , and lowered gradually by hoisting rope . When the top of the splined section reaches

- n the worm gear, it is discon ected from the stem proper and an i raised , d another section of standard p pe is added beneath

- ﬁ tted it. Cross arms, with rollers at their ends, are attached THE SINKING— DRUM PROCESS 87 to the stem at intervals the rollers bear against the sides of the completed shaft and prevent the stem from buckling . The material cut by the borer is collected in two heavy

FI 1 4 . G . Sack Borer

l canvas sacks fastened to the backs of the cutters . Former y they were rigidly attached , and the whole apparatus was ﬁ ll ed . hoisted every time the sacks were Now , however, the sacks are mounted on frames sliding on two pairs of 88 PRACTICAL SHAFT SINKING

i d - s gu des attache to the cross arm on the stem , and are

i i i . hoisted by l ght, ndependent eng nes The sack borer is adapted to clay and sand . is The Mammoth Pump. This an application of the air in wi s lift , used conjunction th a percus ion borer or large

4 . . 3 e A churn drill , Fig A discharge pip , open at both ends, is carried down along the boring rod from the surface and is terminated just above the point of the borer . A com pressed- air pipe B isalso carried down the rod and connected A into the discharge or suction pipe near the bottom . The

op enmg

42 . s ss FIG . Con truction of Sinking Drum for Hydraulic Flushing Proce

borer being in operation , the air is turned on and a stream

i r . of water, mud , and sand is l fted through the discha ge pipe The pump will handle practically any material that will di enter the scharge pipe . The chief difﬁ culty with the sinking drum has been the thickness of iron required to withstand the earth pressure n rs at great depth, and uncertain strai s caused by boulde ﬂan s i under the cutting edge . The internal ge on the tubb ng cannot be made very wide without interfering with the free in passage of bor g tools in the shaft , hence the strength of hi e the lining depends on its thickness alone . T s has reach d

7 in hi r in e l } . , and at that t ckness collapse has occu red s vera THE MAMMOTH PUMP 89

FI 4 n nd r G . 3 . Compou d Drum and Mammoth Pump a Bore

A Ov erﬂow te B r ss , Suction Pipe and of Muddy Wa r ; , Comp e ed C as ai D A E ss e ds. , M onry C on ; , Sho , Acting on nchoring Ring ; , Anchor Ro 90 PRACTICAL SHAFT SINKING

i as cases . Further ncre e is not practicable on account of the weight of the segments and the difﬁ culty of handling

. l si them The cost would a so be exces ve . The compound sinking drum (patented in Germany by P tt i Mr. a ber i g) is a dec ded mprovement . In this, occa sional rings of tubbing are provided with broad internal flan es e se fille wi g , and the space betwe n the is d th concrete in i f or brick, leav g the nterior of the sha t perfectly smooth . o r nl ns The mas n y not o y strengthe the tubbing, but also i i adds weight where it w ll do the most good, and exped tes sinking . The friction and adhesion between the ground and the fl r l ushin . i drum have been lessened by hyd au ic g For th s, the shoe and three or four rings of tubbing immediately i r above it are made sl ghtly la ger than the rest of the lining . r s In the upper side of the shoulder thus fo med, water pa sages i are prov ded which are connected to a pressure pump . i i ki and is ar Wh le s n ng, the pump is operated the drum p tially surrounded by a hlmof water . This expedient has been very successful . (See Fig . The sinking drum is sealed to the solid measures by forc i k ing the cutting edge nto them by the full power of the jac s . If necessary the shaft can be bored into the rock by the

- T l i . he Kind Chaudron method , as wil be expla ned later entire process will probably be made clearer by a short description of an actual piece of work . 5 Rhein reussen li -am Shaft , of the p Col ery, Homburg

i G 500 ft. Rhe n , ermany, was expected to penetrate nearly ki i of quicksand and mud . Sin ng was started with a br ck t 4 ft. C . 3 caisson , Fig , inside diameter, with walls abou

hi 65 ft. ft. thick . T s reached a depth of Nine feet of concrete was placed on the bottom under water and the shaft i D E s pumped out . The anchor r ng , anchor rods , and pre i 3000 sure ring , des gned for a maximum pressure of tons, r r s were erected and a brick inner lining built a ound the od , f reducing the diameter of the shaft to t. mF i diameterof A compound dru , w th an outside

92 PRACTICAL SHAFT SINKING

f r f r holes are bored about 3 t. apart ; the fo m o the f ozen i At ﬁ rst i ground is consequently cylindr cal . the cyl nder as i i s a al e s is hollow, but the freez ng cont nue , it gr du l y b come i is ma solid ice . Excavat on then commenced , the frozen terial being loosened with picks or light charges of explo

siv es. In Europe 70 or 80 shafts have been sunk by the freezing in s ases process, the thickness of the soft ground ome c

00 ft. s s are in reaching 3 Most of the e shaft France, Bel G e in gium , or ermany ; a few have be n frozen England by r s continental contractors. In the United States the p oces i in has so far found a very lim ted application . One shaft 1 f 00 t. i s Michigan was frozen through about of qu ck and, and an unsuccessful attempt was made to~ freeze a shaft in

Pennsylvania . A number of European shafts started by the freezing method have been completely lost through some accident . hi in Notwithstanding t s, the method is be g improved and greater and greater depths are attempted and reached .

- t Water bearing rock strata are successfully frozen . A shaf in Belgium has been sunk by freezing through 700 ft. of soft ground and wet rock . i i i A detailed descript on of the freez ng process , wr tten by

Mr F. in u 1 909 . Sidney Walker, may be found the Aug st, Mines and Mincrals issue of . iffi culties i in f i i The chief d met w th reez ng, especially n are in s deep freezing, deviation of the bore holes, salts olu in i th tion the ground water, bursting freez ng pipes , and e fir tendency of ice to flow under pressure . The st trouble n r i can be met by measuri g the d ift of the holes , and by bor ng additional holes when the divergence of those already bored

. s rs r r e is too great Salt olutions are of cou e ve y ha d to fre ze, and their presence in the ground necessitates a much longer r r s freezing pe iod than would otherwise be necessa y . A bur t i pipe allows the freez ng solution itself to ﬂow into the ground, forming a soft spot that it is almost impossible to freeze at all . The obvious way to prevent this is to use very strong THE FREEZING PROCESS 93

i u a i tested p pe , and it is now fo nd advis ble not to c rculate r i the freezing solution th ough the bore hole cas ng itself, but to insert an inner and outer freezing tube and to withdraw flowa e n the casing . The g of ice ca not be prevented and limits the depth for which the freezing process is feasible . i Hard freezing checks th s tendency . A freezing period long enough to thoroughly solidify the ground is the fi rst essential for successful sinking . The smallest crack or seam which will admit a few drops of water will soon enlarge itself until a disastrous break- through is sa occurs . It also neces ry, from time to time as the shaft i wi s sus is excavated, to support the s des th ome form of pended lining . l G i — The Anha t overnment Salt M ne, at Leopolds Hall , is a s i Stassfurt , an ex mple of a succes ful appl cation of the i i 1 freezing process . Dr ll ng was commenced early in 899 and 26 holes about 5 in. in outside diameter were drilled on a f i s to 325 t. lli ft. c rcle and ca ed a depth of The dri ng was 1 B lt 900. was diffi cu , and not completed until June, y this time the freezing plant (which consists at most shafts of two 75 horse power ammonia compressors) was ready 22 and it was started June . Sinking was commenced on 1 9 f 2 30 t. September , and on September , at a depth of , a small leak which existed in the middle of the bottom broke fl i through and ooded the shaft . Freezing was then cont nued an n d was in r . until the end of November, sinki g aga sta ted

B 1 901 202 ft. e and y the end of February, , had be n sunk, the shaft was then lined with iron tubbing . The space between the tubbing and the rock was ﬁ lled with concrete i mixed with a solution of calc ned soda . Periods of sinking li ul 4 was and ning then alternated, until on J y , the shaft T lined complete to the bottom of the frozen wall . he total 2 an time required for a depth of 3 5 ft. was therefore two d

— 1 1 ft. one half years , an average progress of per month .

i C . . The Chapin M ne c , Iron Mountain , Mich , decided to sink a shaft in the center of a small valley crossing its prop i n l erty. Attempts to s nk by ordinary methods havi g fai ed , 94 PRACTICAL SHAFT SINKING in 1887 a contract was let to the Poetsch- Sooysmith Freezing At i e ss. Cc. to s nk the shaft by the fre zing proce the site of f ro was 95 t. i a the shaft the ck covered by of qu cks nd , h ix rs. sa ad so d w gravel , and boulde The nd me clay m e ith fl w it e 1 er . and o s ik , contain d p cent of water, would almo t l e water . The installation of the freezing pipes was performed by w fi ni h i C . as s n the Chapin Mine c itself, and ed the summer - - n 1 . l nl 888 o . of Twenty six i bore holes , spaced eve y on 2 -f r ffi c 9 t. t r circle, were d iven and cased o ock, great di ulty being experienced in keeping them vertical on account of

- rs. e in. ﬂush the boulde Eight inch fr ezing pipes g thick, i inside and out and closed at the bottom, were lowered nto an the holes d the casings were then withdrawn . Inner tubes l é in. in diameter were lowered into the freezing

ih . . tubes, their lower ends being kept 8 above the bottom in The upper ends of the tubes were connected , as shown

- - - . 44 r i 0 t n i Fig , to the b ine p pes of a 5 o per day capac ty i — Linde freez ng plant operated by a 55 horse power engine, driven by compressed air . Two hundred c ubic feet of brine i a 2 l 5 . s consist ng of . per cent olution of calcium ch oride was i used for the freezing ﬂuid , the entire quantity mak ng a

- circuit every thirty three minutes . Excavation and timbering were started fi fteen days after freezing was begun and were continued for seventy-eight i days , when rock was reached in one end of the shaft . Dur ng this period two and a half days were lost by the interrup s ee tion of the air upply to the engine . Some water had b n fi nding its way up through the unfrozen core in the middle of the shaft ; the quantity now increased and sand began to it fi r come in with . The shaft was at once lled with wate and an additional freezing pipe put down. Four months and a half after freezing was begun the shaft was sunk 7 f 8 t. A n or into the rock . t this point enough water fou d its way through the fi ssures in the rock to thaw out the sand at the rock surface , and it was necessary to again flood the

. was shaft Before this was done , however, a coil of pipe

96 PRACTICAL SHAFT SINKING

r i attempt was made to sink the second by the f eez ng process. f Bore holes were put down from 5 to 7 t. apart in a circle s r e around the proposed shaft, and ca ed through the su fac i was cir i . ur and 5 ft. nto the rock A freez ng mixt e then se hi the culated in the pipe for ven weeks, at w ch time fi rst s caisson of the shaft reached rock . It was then di n covered that the rock, i stead of being solid as supposed , 1 fl was fi ssured for 8 ft. below the surface . As a large in ow rr in fi ssures of water occu ed the , the company decided that it would be impossible to successfully seal off the water inthe f in se i 5 t. cond shaft with the freez ng tubes only the rock , was was e and the attempt abandoned . The shaft th n sunk

by the pneumatic process, and although some time had elapsed between the abandonment of the freezing and the s l sinking of the cais on, the ground was found to be sti l

frozen hard . The writer wishes to acknowledge his indebtedness to “ Mr. bo k Difﬁ cult J Riemer, from whose ok , Shaft Sin ing in he got many facts about the sinking dru m and i the freezing processes in general , and a descr ption of ur i E opean applicat ons . The descriptions of the American freezings were abstracted from the Transactions American 1 4 Society Civil Engineers for June , 90 .

a Difﬁ cult ases J e t s t d fro th Sh ft Sinking in C , by Ri mer, ran la e m e W an J . u . B i n tt J . C . Germ by Bro gh L ppi co o , Philadelphia, 1907 . CHAPTER VII

- P THE KIND CHAUDRON BORING ROCESS . CEMENTATION OF WATER-B EARING FI SSUREs

SINKING in wet rock may be accomplished in two ways : i mechanically, by break ng and removing the rock under water ; by hand , by closing the seams in the rock, thus pre infl w i venting the o of water, or by lift ng the water as fast as it flows in. The first plan can be carried out in one way only the boring process . is i i The second accompl shed by the freez ng process, s fi ssur already de cribed , and by direct cementation of the es of the rock : water is most frequently lifted by sinking pumps

- suspended in the shaft , although the old Cornish spear rod e pump is still sometimes used for large quantiti s of water .

A system of water hoisting has also been developed .

i - The B oring Process. The K nd Chaudron boring process has previously been referred to as a process devised for sinking through rock measures containing such quanti ties of water that hand sinking is impossible . It is exclu siv el y a European method , and so far no shafts have been in hi M bored t s country . The process was originated by . 1 4 1854 Kind , a well borer, in 8 9 . Between that date and he attempted to sink three shafts in Moselle and in West i phal a, but failed owing to the inadequacy of wooden

M . tubbing . The scheme was then taken up by J i Chaudron , a Belg an engineer in France , and was improved by himto such an extent that his name is now always ass w ociated ith that of Kind . Subsequent improvements of value have been made by Riemer and others , and have been patented in Europe ; at present the ﬁ rmof Haniel 97 98 PRACTICAL SHAFT SINKING

s r r and is Lueg, of Dus eldo f, cont ols many of these patents best equipped for boring shafts . Kind ’s original plan was to bore the shaft in one opera diffi cult l i m it tion . The y of co lect ng the broken rock ade t in adv isable o bore two stages , and a small hole , having a diameter one—third to one-half that of the fi nished shaft is now bored in advance . The muck in this is removed by i l o a special bucket w th flap va ves in the b ttom, so arranged is h that as the bucket lowered the muck will enter . W en the bucket is raised the valves close . The small shaft serves as a guide for the large boring o tool, as well as for a collect r for muck , and it is usually

1 ft. bored about 00 ahead of the large boring . The cutting edges of the large borer slope down toward the center ; the i ri s . bo ng , therefore, slide nto the small shaft The large t tool thus has always a clean surface o work ou . i as Bor ng is usually adopted a last resort . In regions th where large ﬂows of underground water are expected , e shaft is sunk by hand until the water- bearing strata are reached and is then cleared for boring . Care must be taken to keep the shaft free from timbers , permanently fastened

s . pumps , and pipe , etc , so that when it is ﬂooded all impedi

. i ments to boring can be hoisted out If this is not done, t will be necessary to cover the bottom of the shaft with a e thick layer of concr te, deposited under water with a grab in i an bucket , order to perm t the shaft to be pumped out d cleared . h i r W en boring is started , it is carr ed th ough the water bearing strata and some distance into the impervious ground beneath . The shaft is then lined with rings of cast iron tubbing the placing of this tubbing is the most ingenious feature of the boring process . (See Fig . After the shaft has been cleaned out and the boring an tools removed , a heavy platform is built over the shaft d s hi tw upon it the mo s box is erected . T s consists of o stuf n — hi h rings of heavy tubbing , forming a large ﬁ g box w c ﬁ lled es is with moss, and is so designed that an upward pr

100 PRACTICAL SHAFT SINKING

rifi g is lowered into place and bolted up . The process is then repeated . Since each ring of tubbing weighs less than the water it d h colunm displaces , after enough have been adde the w ole n i s are i of tubbing will float . The ha g ng rod then d spensed as i on n is s with and , each r ng is bolted , the tubbi g unk by his is in l admitting water . T cont ued unti the moss box reaches the bottom of the shaft . The whole column is fi ll i then allowed to w th water, and, all buoyancy being re i i ru s the moved , the ent re weight of the tubb ng serves to c h

i - moss outward against the s des of the shaft . A water tight joint is thus made at the bottom . The space between the tubbing and the sides of the shaft f wi is then illed th concrete, and , after this has set long r is enough to tho oughly harden , the shaft pumped out and the bulkhead removed . The concrete is usually placed i with small ﬂat buckets lowered w th ropes . 4 o s . The boring tools , b rer or Fig 6, are made ee i i r i of cast st l prov ded with nse ted teeth, and we gh about 20 o 10 tons for the small and t ns for the large tool . They are suspended by heavy timber rods from a walking beam

i r r in . n operated by a s ngle la ge, ve tical steam cyl der Betwee the walking beam and the rods a chain connection is pro i s hi rs h v ded , by mean of w ch the bore can be lowered as t e “ ’ ” hole deepens . At the bore master s platform on top of the shaft there is a swivel connection and a long lever for rotating the borer slightly between blows . The head- house is a tall structure with two wings in r which are stored the va ious tools . All are hung from small r trucks which can be readily un out over the shaft . Two i and are t ho st engines cables provided , one for the bucke and the other for the borers and tools .

" Considerable diffi culty is encountered in boring through fi ssured r ri he ground and th ough strata of soft mate al . In t fi rst case the teeth of the borers are liable to breakage ; in

s s of i . l of the econd , large ma ses mater al fa l out of the sides l h s . as the shaft , ometimes burying the borer A specia tool CEMENTATION OF WATER— BEARING FISSURES

i been devised for ﬁ shing out broken teeth , large p eces of ih ri is re s rock, etc . A falling of mate al p vented by heet ﬂat iron cylinders, lowered from the top and suspended by

ropes . These cylinders have no hydrostatic pressure to i - 3 in. resist, hence need not be heavy . They are bu lt of 4,

60 ft. plate, in lengths up to

- FIG . 46 . Crosssection of Boring Tower

It has not been found practicable to use segmental i i i o i ifﬁ tubb ng rings for l n ng b red shafts, ow ng to the d culty i r - of mak ng the ve tical joints water tight . The maximum i m d ameter at present, therefore, is li ited by the size of the l o 14 f t. i sing e ring which can be transported ab ut d ameter .

f . ri is 1 8 ia. to 3 t The bo ng made larger, depending upon the

character of the ground . Ordinarily the small borer is

15 - f s ft. 8 t. 14 f about acros , and the large one % for t. tub i if is x b ng, but much bad ground e pected and the use of PRACTICAL SHAFT SINKING

- r several sheet i on cylinders is contemplated , the large borer f 1 7 ft . . t is made t or . across o start with The speed made in boring shafts has varied so greatly t fin ﬁ r that it is hard o give de ite gu es. Under favorable l 2 0 ih . conditions the small tool wi l advance per day, and the large one 7 or 8 in. If to the time required for actual boring is added that taken for lowering sheet-iron cylinders n and tubbi g, it will be seen that an average progress of 8 to

f . 10 t. per month is all that can be expected The costs of s in i hi the boring proces are, consequence , exceed ngly gh , but for the very diffi cult sinking conditions obtaining in some parts of Europe it is the only process that is unfailingly ! successful . n n Direct Ceme tatio . The injection of cement grout under pressure into fi ssured rock has been attempted only un recently . Immediately aro d the proposed shaft a num ber of holes are drilled through the fi ssured rock into the s solid mea ures beneath, and grout is forced into them until l ll v fil ed . set all cre ices are It is then a owed to , and , if the i i work has been properly done, s nking can be continued n the dry . The water—bearing fi ssures can best be located by using in core drills rather than percussion drills boring the holes. v r If only one cre ice exists, the grout will flow di ectly into it if fi ssure i h ; , however, the rock is d for some d stance , w ile r u fl win g o t is o g into the upper cracks, the hole beneath them t ma b m fi lle y eco e blocked before the lower cracks are d . In thi the scase water will not be completely shut 0 11 . Up tothe present time the blocking of the fi ssures 1n any considerable depth of rock has only been accomplished by s successive cementations . This was done in the two case

. i described below The writer bel eves, however, that if r the holes are bored entirely th ough the wet rock , a method l can be devised for ﬁ ling the cracks from the bottom up . A plan that might be worked out would be to case the holes

"‘ For detailed infomation on thisprocess see: Shaft Sinking in Diﬁ cult

as s J R . C e , by iemer

104 PRAC TICAL SHAFT SINKI NG

were t en run nto the fi rst e c mete fi llin it a h i pip , o pl ly g , fter w his ir 475 sa w th r r . re hich e bo e holes e e fi lled T qu ed cks. The pumps on the bore holes were worked continuously w il the w r in t h e pipes e e be g grou ed . The grout was allowed to set for nineteen days before the w te was t f th s a t I t was t e n a r pumped ou o e h f . h n fou d

h ~ f that t e leak was completely closed and a 2§ t.

o P es Fissurw in s FI 4 . e h ft G . 7 L cation of ip and L n S a

o o . r grout had formed on the b tt m The rest of the g out ,

2 2 ft. h f n . 8 . a ru i s amounting to cu , d nto the i sures un a The bed of grout was s k through very c refully, and h 1 f . A the shaft deepened to 70 t and lined to t e bottom . t f infl w n 1 5 t. o i 8 a second was encou tered , the water break ng fi ur in through the vertical ss e referred to above . Two more i grout pipes were inserted , their lower ends be ng driven f fi s t sure. r t 3 and 6 . into the Nine hund ed sacks of cemen CEMENTATION OF WATER— BEARING FISSURES

run i i i were nto the longer p pe in n ne hours, when the lower ends of both pipes became closed . After twenty-eight days the water was pumped out and fi s sinking was resumed . The large sure was found to be an this time thoroughly cemented, d further sinking and lining i r a diffi c l was carr ed on without pa ticul r u ty. fi rst th mi It was found in the cementation, where e xer 2-in discharged directly into . pipes, that considerable air hi r was carried down with the grout . T s hinde ed the flow very greatly, so that in the second cementation the grout 1 in. 2 i pipes were made 5 diameter above water and 5} n. i was wi under water, a h gh narrow tank connected th the l top of the grout pipe, and a va ve was provided to regulate fl w l h . t e o from the tank , which was kept fu l The mixer r k discha ged into the tan through a trough, with gratings for removing air. The more important conclusions reached were 1 r i . Fissures in rock can be cemented th ough p pes or bore holes . 2 rs i nn . Sand , marl , boulde , clay, and sl me ca ot be cemented . hi 3 . T n beds presenting continuous openings can be c emented by pumping from bore holes outside the shaft . Direct cementation has also been applied at the Anzin r and the Bethune collie ies in Europe . Direct cementation has only been attempted in America 4 in one instance . No . shaft on the Rondout siphon of the Catskill Aqueduct encountered a flow of water of 750 2 gallons per minute at a depth of 70 ft. The shaft is rect f 4 in a l r w e 8 t. . ngu a ith thr e compartments, measures only

' 20 ft 4 in aﬁ r s i or . d o . r o X in the clea , and thus very l ttle pp tunit i I n ddition y for handl ng large pumps . a to this fact the water was strongly charged with sulphureted hydrogen

as r . g , which acted very painfully upon the eyes of the sinke s

After no progress had been made for several weeks, it was decided to try grouting . Most of the water came ir hi d ectly out of the bottom . The water level was held wit n 106 PRACTICAL SHAFT SINKING

ft the o o 1 about 5 . of b tt m and a number of holes from 0 to

- dr d w ro r . 1 8 ft. deep were ille ith ck d ills Two inch pipes to s s 1500 were connected the e hole , and about sacks of i i d o . i cement , m xed as neat grout , were force nt them Th s reduced the ﬂow of water in the bottom from 525 to about

50 gallons per minute . t ﬁ ssures s o In order o block the below the haft bott m, a r to diamond drill was set up on a platfo m at the p of the shaft ,

95 ft . r . and six holes were d illed , each about deep A column — r to o the of 3 in. pipe extending f om the p to the bott m of shaft served in each case as a guide for the drill rod . These — r holes passed entirely through the water bea ing rock , which ﬁ ssure consisted of a badly d sandstone , and penetrated an

- impervious stratum of grit beneath . Two inch grout pipes were now connected to these diamond-drill holes and 183 sacks of cement were forced into them . This entirely cut 11 0 the water in the bottom . It was found upon pumping out the water that all the fi ssures l upper were completely fi led . When sinking was u resumed , however, it was f rther found that the drill holes had become blocked before the lower fi ssureswere completely fi lled , and the water, therefore , was not altogether shut

off. s i After the cementation it was , nevertheless, po s ble 1 f to handle the water with pumps and sink about 0 t. a week in the ordinary way . In ﬁ lling all the holes the grout pipes were carried to the top of the shaft . The grout was mixed and fed into a tank attached to the top of each pipe . When no more grout would ﬂow by gravity , the opening in the tank was closed , air s and pres ure applied on top of the liquid grout . The 80 pressure ranged from lbs . to a maximum of 300 lbs . per square inch , which last was obtained by means of a special air compressor .

m s Nore. For further infor ation about method of grouting see Ap pendix A.

108 PRACTICAL SHAFT SINKING

h h i ﬂ w him ise. n o otherw W en t ere is only a slight of water,

' a small vertical pump with hose connections is certainly in i very easy to hang the shaft ; on the other hand , a hor i 1 r m zontal pump , w th a capacity of 50 gallons pe inute

4 FIG . 8 . Vertical Sinking Pump

i i h or less , will work perfectly when hung w th a br dle . W ere is ﬂow there a considerable of water, and where the shaft is large enough to accommodate a horizontal pump or pumps f i o the requ red capacity, this is the type to use . Where the LIFTING WATER 109

shaft is so small that there is not room in it for enough u to a horizontal p mps take c re of the water, a vertical

pump is of course a necessity . ’ The writer s reasons for preferring the horizontal pump

1 ri is i r . The ho zontal pump l ghte than a vertical of the

same capacity . 2 r si . In the la ger zes the horizontal pump is much more man a n accessible , since a can walk rou d it and work at any

part of it on a level platform . It is necessary to climb 6 or r r 8 ft. to get f om the wate end to the steam end of a big

vertical pump . B i r 3 . y provid ng a proper bridle, the ho izontal pump

can be hooked on to and lifted as easily as the vertical . 4 300 al i . For a pump discharging over g lons per m nute, the recoil at every stroke is so severe that hose or other ﬂexible connections will not stand when the pump is hung .

freely . This applies to the American style of vertical sinking n uc r pump , where the center li e of neither s tion nor discha ge i i l i co ncides with the center of suspens on , as we l as to a hor

z l it s r i onta pump . In both cases is neces a y to furnsh rigid r as i r suppo t , and it is easy to set two hitch t mbers in a ho i zontal plane for a horizontal pump as it is to set them in a r ve tical plane for a vertical pump . In sinking several shafts in which the flow of water in o 800 1 500 the bott m varied from to gallons per minute , the writer has obtained the best results by working along the followi ng lines : Provide an absolutely reliable boiler plant of ample

. i capacity Sinking pumps are frightfully uneconom cal , ui 2 2 req ring from 00 to 50 lbs . of steam per actual horse power hour ; a shaft in which 1 000 gallons per minute must 1 __ f 1 000 X 8 X 300 t' f 3 300 t. be lifted will , therefore, require

200 505 - i X horse power of boilers for pump ng alone . 30 4 . 9 Put in a water ring, Fig , and a stationary pump 1 10 PRACTICAL SHAFT SINKING wherever it is possible to reduce the water in the bottom W - by so doing . hen the water bearing stratum has been k h “ ” sun t rough , open up a lodgment or reservoir in one end of the shaft and install a compound pump . For handling water in the bottom provide at least 50 r 350- per cent . extra pumping capacity ; say, fou gallon

IG af 4 . e F . 9 Section of Water Ring for Timb red Sh t

900 the pumps for gallons per minute , two in each end of

. . 50 shaft Set bearing timbers , Fig , as close to the bottom 1 0 ft. as is safe , and lower pumps alternately at a time ,

- 2 - ﬂ 1 f 0 ft. an ed 0 t. keeping and g lengths of steam , exhaust , and water pipes ready to put on. If each new set of timbers 1 f . is placed 0 t from the bottom of the shaft , the maximum f suction lift at any time will thus be 20 t. Make swinging joints on all pipe lines at the pumps , to take care of vibra tion and expansion and of variations in the spacing of the

1 12 PRACTICAL SHAFT SINKING

ste s ki . . ee m , pac ng , etc ) on hand , and to k p the follower i s bolts and nuts tight . It is adv sable to fa ten these securely s li t ro a i with cotter pin , or by dril ng h ugh the he ds and w ring

them together . Pumps will run satisfactorily on compressed air if the fﬁ i l As ir is d su c ent to ee . a reheate y prevent fr zing a rule, the cost of the air plant makes it imperative to use steam s x s on the pumps . Both team pipes and e haust pipes hould

- be lagged with some water proof covering . At s s r a be t , many delay will occu when water is h ndled . 0 900 mi 1 5 t 20 f 8 t. For a shaft making 0 to gallonsper nute, o per month is good progress; the labor cost may easily reach 1 2 i ins ﬁ cient mhi $ 50 to $ 00 per foot . Sink ng with uf ac nery is impossible . In this country water is usually regarded as an unfor t ate an un accident , d when encountered is met by begrudged additions to the plant . As a result much time and money ar s the i i e wa ted . In Europe, on the other hand , m n ng dis t icts the r have been more fully explored and developed , and

- s position of water bearing strata is known . Preparation are made in advance for handling large quantities of water . The shafts are circular and are lined in sections as the sink ing proceeds with brick or water- tight iron tubbing ; their large diameter and freedom from cross- braces make it pos An r sible to use more powerful pumps . actual measu ed flow of from 2000 to 2500 gallons per minute in the shaft bottom is as much as has been successfully taken care of in h America . In the two English cases cited below two to t ree

times this much water was pumped . In the Transactions of the Federated Institute of Mining 1 Mr. H . 5 3 W. Engineers , Volume III , page , Chambers

d C nisb r Y . escribes the sinking of two shafts at o o o, orkshire 3 f 0 t. f i Eight X 7 t. 6 n. Lancashire boilers were installed , and

sinking was then commenced in both shafts simultaneously .

1 6 ft. The water was handled by pulsometers to a depth of 5 , when an inﬂow of water occurred that made it necessary to put in very much more powerful pumps . LIFTING WATER 1 13

i C . i i . 51 The s nk ng pumps , Fig , were made by Ba ly o , f to run u o Salford , and were designed s spended in the shaft without other support than two suspension ropes which also s carried all pipe lines. A tele copic suction pipe is provided in stead of suction hose , and the axes of both suction and dis r i n cha ge pipes coincide with the ax s of suspe sion . All vibrations caused by the strokes of the pump are , therefore , vertical and cause no dangerous sideways motion in the pipe l i ines . The pump tself consists of three hollow plungers the upper pair are stationary and over them slide barrels i which are connected to the steam piston . The th rd barrel o is secured , t gether with the pair of stationary plungers , to ” the steamcylinder by means of connecting rods . The pump is thus what is here known as the differential plun ger type . Two discharge pipes are led from the top of the s i upper stationary plungers along ide the steam cyl nder, and are joined above it by a tee from which the column pipe rises . The two suspension ropes are led over pulleys at the shafthead or to the drum of a hoisting ( capstan) engine , and are the pump and all piping hoisted and lowered together .

A telescopic joint is put on the steam pipe at the shaft head , the the discharge pipe is turned sideways over a trough, and exhaust pipe stands straight up . The arrangement of pump 2 and pipes in the shaft is shown in Fig . 5 and the method of supporting the pipes is shown in horiz ontal section in 2 5 a. Fig .

Six pumps of this type , each with a capacity of to 35 Imperial gallons per hour at strokes per minute , f were needed to sink the shafts to a depth of 300 t. In this depth the maximum quantity of water discharged from 6600 i both shafts amounted to gallons per m nute , although the tubbing was carried along with the sinking . Two more r pumps we e then obtained , and the eight were arranged to f t 300 t. lift the water in two stages , as was the maximum lif ﬁ nall off of each pump . The water was y shut at a depth of

9 f f . . 3 5 t. in one shaft and 369 t in the other

1 16 PRACTI CAL SHAFT SI NKI NG

steami e a ter bein drawn its full len th out of the p p , f g g - ack an an ther len th insert x was ushed b d o ed . stufling bo , p g A stop v alve and a lubricator were placed in the fi xed lad was in char e t steampipe on the surface. A g o regulate st amas re uired he bein in co m the supply of e q , g m unication in the af b means of si nal with the sinkers sh t y a g bell . The speed of the pumps was thus controlled and lubrication effected without any one being in the shaft for those pur ” msa . Perhaps the most remarkable achievement in the line of wet- shaft sinking that was ever accomplished was the sink r i t D r h ing at the Horden collie y n Sou heast u hams ire. This work is des cribed at length in a very interesting paper i Th rs e i ee n c ar e. e a is by Mr. J. J P e t , the ng n r h g p per published in the Proceedings of the Institution of Civil XX i eers l e ar 3 . Eng n , Vo um CL III , P t t s ree s a w re su k m A thi colliery th h fts e n , two of the simultaneously the third was put down to the level at which tes fl w o r r n the grea t o of water ccu red, and the e stopped u til

e l . Mr r as r s . s the other two each d the coa me u e Pre t , after

i to use l - nis careful consideration , determ ned the o d style Cor h n r a pump and i stalled a ve y rem rkable plant, comprising over 3000 boiler horse-power and no less than four sets of - -f 30 in. bore by 6 t. stroke pumps . Each set consisted of a so and pair of pump cylinders hung as to balance each other,

- - if capable of being arranged as a high and a low l t set. The i i pumps were dr ven by the permanent hoisting eng nes,

- provided with an extra jack shaft and gearing . The maximum quantity of water handled simultaneously from all three shafts amounted to 9230 Imperial gallons per 1 ll s minute , and the maximum from one shaft to 63 0 ga on i per m nute , this quantity being pumped from a depth of

300 ft. The shafts reached an average depth of about 540

ft. before the coal measures were reached and it was ﬁnally

possible to tub back the water . A system has been developed in England for hoisting water from a sinking shaft without the use of any high LIFTING WATER 1 1 7

m w as so - pressure pu m. It is kno n the Tom n water winding his Mr. m a process. To son puts in perm nent hoisting i i s in i i r e eng ne , places gu de the shaft as the s nk ng p oce ds, s r are and u es la ge lifting the water . The tanks ﬁ lled by low- pressure pumps driven by compressed air and attached to the tanks . This system has been very success ful s i a s in ome nst nce , but has not been used where the quan r r as rea as a n s r titiesof wate we e g t those t Co i bo o or Horden. CHAPTER I X

SHAFT LI NI NGs

SHAFTS are usually lined ; either in order to exclude to li water, or support the sides and prevent the fal ng of fragments of rock . The most common lining material in fact until recently almost the only lining material used for American a a mine shafts is timber, ordin rily framed in squ re sets and ni a lagged with plank . Such a li ng cannot be m de water r i tight and acts only as a suppo t or shield . Wooden ca ssons

‘ and ochers used in bad surface ground are of course built e s to exclud water , but this construction is not fea ible at considerable depths . i ri European shafts are usually l ned with b ck walls , built upon cast-iron curb rings set into the sides of the shaft at intervals . The circular and elliptical sections universal in Europe are in fact accounted for by the necessity for arch r action in a brick lining . The walls a e not designed to but i absolutely exclude water, to lead it to water rngs at the ri curbs and prevent it from dripping in the shaft . A b ck

ﬁ re- lining is proof and durable .

Where it is desired to block back large feeders of water,

- cast iron tubbing is used . This has already been referred r to in connection with the Bo ing Process . Two styles of it w are used in Europe , kno n respectively as English and Ger man tubbing ; the writer knows of no case where it has been hi used for a mining shaft in t s country, but miles of suba . queous tunnel around New York City are lined with bolted

- cast iron segments . h In the last decade , concrete as come to the front as a material for lining shafts . It is gradually being realized 1 18

120 PRACTICAL SHAFT SINKING

r is moistu e, the cheapest construction an unlined rectan gular shaft with several vertical rows of buntons to which

the guides and ladders are fastened . These buntons cor respond to the buntons and end plates of a square- framed set i i of t mbers , and are set nto pockets cut in the rock .

' 2 6 - o "

t ombercd Coat Houst

&nch

mr ' OeZaLL o co e 3 6 0 a f 0 41. f sed e / 0 6 0 8

[nd q’d antan

oe v cu ed to cead wate r back of

Ot/ref ‘ Meth od s cf

FIG . 53 . Timber Sketches

s They mu t be set correctly in parallel vertical planes, and should be level and in line horizontally, but absolute a ccuracy in this respect is not essential . The pockets are “ “ ” known as hitches , the box hitch is cut square ; the drop hitch ” is cut with the top sloping back so that after one end of the bunton is placed in the box hitch the other SHAFT LININGS 121

r may be d opped into place . The buntons are usually set

- ft. s so on 5 center vertically, that workmen standing on a platform on one row of timbers can cut the hitches for ff l i s . the next row w thout ca o ding (See Fig . After the buntons are placed in the hitches they are i secured and held in l ne by oak wedges driven in tight . The hitches are cut just enough larger than the timber to allow for wedging . The depth depends upon the rock 1 2 t 1 - hi s eciﬁ cations o 8 in. p usually call for tches , but, as a in matter of fact , any rock hard enough to stand without

- i support a 4 in. hitch will break the t mber .

IG n ons F . ft t B u t 54 . Sha Timbered wi h Only

Hitches are usually cut by hand with hammer and bull i mm d e po nt , but pneumatic ha ers can be use to advantag in i hard rock . When work ng by hand a pair of men (ham mersman and holder) should ﬁ nish a pair of hitches in an i - i e ght hour shift . The labor cost per t mber is thus about 5 i 7 . 3 net , or $ including headmen, eng neers, etc Rin Timb r i g e . The commonest form of timber l ning, i and the one that is used in all large shafts, consists of hor z - 4 f ontal 6 t. and square framed sets, spaced to centers l 2 i agged with to 3 n. plank . (See Fig .

In a previous chapter, the terms bunton, end plate, wall eﬁ ned s plate, and punch block were d as the cros struts, end i t mbers , side timbers, and posts , respectively, in a square s framed set of timber. Each set consists of two wall plate 122 PRACTICAL SHAFT SINKI NG

or and two end plates halved at the corners, and one s a ir more bunton , butted ag inst the mer faces of the wall buntons s s plates to serve as struts. The al o divide the shaft

' into the requisite number of compartmentsand aﬁ ord support s r e for guides , etc . The ets are sepa at d by posts or punch b blocks placed at the corners and at the end of the untons.

Lagging plank are set vertical and close together . They i are usually placed back of the t mber, and are held by cord wood or slabs packed into the space between them and the r i as r ock . Th s packing also acts a suppo t for the sides of i s the excavation . To prevent plank from falling n ca e of i to d splacement of the packing, they should be well spiked

the timbers top and bottom . The best construction is ff 2 2 r ri e ected by spiking X in. st ips ho zontally in the middle of the outer faces of the wall and the end plates the lagging boards are then out two inches short of the center to center i s . spac ng of the ets, and are inserted between the strips i is In hard rock pack ng is not necessary , but lagging usually needed to prevent water from splashing into the hi shaft and to lead it to the rings . In t s case , the lagging boards are placed between the timber sets and are held by strips nailed to the top and bottom faces of the timbers. Sometimes these strips are beveled so as to lead water to the back side . When a shaft has been sunk without support as far as i 1 the cond tion of the sides will permit say 50 to 00 ft. a set of hitch timbers (dead logs or bearing timbers) isplaced t hr as a founda ion , and the timbering is built up t ough the nl e u ined s ction . The hitch timbers are set into hitches cut in the rock as described above , and must be perfectly level

and in line . Since they are to carry a great weight the hitches must be deep enough to afford a bearing equal in

strength to the timber . The hitch timbers are often made 1 2 i deeper than the ring timbers ; 8 X h . hitch timbers, for i 1 i ﬂ or 8 0 n. . o nstance , for X ring timbers A heavy is built over the hitch timbers between the ﬁ rst set of timber

and the wall, to carry the packing . (See Fig .

124 PRACTICAL SHAFT SINKING

i s r i rs serv i shaft , pa r of ve tical t mbe ng both as posts and ai s b girders are placed ag nst the ide, and untons are set

. r ili s ri s are so in between them .Ve tical na ng t p al put the

Fi . corners . (See g i ri i ri B rick. The th ckness of a b ck l ning va es from 1 in i . di 9 to 8 , depen ng on the s ze of the shaft and the nature

- - 13 in. s i ss 1 of the rock . A wall is the u ual th ckne for a 6 ft. i i 1 s se 50 to 00 ft. shaft . The wall bu lt in ctions long, each of which 1s founded on a curb of wood or iron built m seg in ments and set into a groove the side of the shaft . This o i groove is cut by hand , the b ttom be ng made perfectly r i x level , and the curb is ca efully wedged nto shape e actly concentric with the shaft . If much water leaks into the be i is shaft in the section that is to l ned, the curb made of iron and the space behind it is ﬁ lled with wooden blocks i in as i r and wedges dr ven tight, w ll be desc ibed in detail is . rin s i s later A water g ca t on the n ide of the curb, and drainage pipes leading through the lining to the ring are provided . (See Fig . The work of setting the curb and building the wall is

' done on a suspended scaﬁ old which israised as required by a r special engine at the su face . The wall is built very rapidly as several masons can work without interference six r r l masons, if kept supplied with b ick and mo tar, can easi y

f . build 6 to 8 t. of wall per shift r k in has In deep shafts ecently sun England , the work been so arranged that sinking and lining are carried on

i . i s multaneously Two buckets are used , one of wh ch hangs in s s r in the the center of the shaft , and pa se th ough a hole ff fﬁ l ' walling sca old . The other hangs su cient y oh center i i ma to clear the sink ng bucket , and is used for supply ng l ff teria to the masons . The ropes which suspend the sca old also serve as guides for the buckets . This method is only feasible for large shafts .

The brick should be made of good clay, burned hard i is enough to w thstand the action of water . Mortar made of quick- setting Portland or hydraulic cement and is used SHAFT LINING 125

as sparingly as possible . The space back of the wall is ﬁ lled i w th concrete, tamped clay, or cinders .

I ron Tubbing. Both English and German tubbing -i consists of cast ron segments and is built up in rings . The

i I . s e u F G . 56 Engli h Tubbing S gment 15 to C rc mference

s English egments , however, have rough edges and no bolts

- and are made water tight by wedging the cracks with wood, whereas the German have machined edges provided with ﬂan es g and are bolted together . Lead gaskets are used to

i . ar 2 f make a tight jo nt English segments e about t. and G f . erman about 5 t high .

FI G . 57 . German Tubbing Segment 8 to Circumference

The process of setting a wedging curb and building up

English tubbing in wet rock is described by Mr. J J Prest as follows : 126 PRACTICAL SHAFT SINKI NG

1 The shaft was sunk about 9 or 0 ft. into the imperme l i 2 of 3 ft. able stratum, of the fu l d ameter , say, , and then ﬁ nished i decreased abruptly to the s ze of the shaft, say

20 ft. i , and the sink ng was continued a further distance of

' scaﬁ 6 or 8 ft. The cradle (walling old) was then lowered

Fl oor Le ad on B earmq u mbe r: t o carry Pack cng

FIG . 58

FIG . 58a. Timber Sketches into the pit bottom and a temporary wood water- ring was x 1 f ﬁ ed on dowels about 9 or 0 t. above the site selected for the bed of the wedging curb . The whole of the water running from the sides of the shaft was then collected in this temporary water-ring and allowed to run off in canvas hogges or trunks at two or three different positions to the pumps .

128 PRACTICAL SHAFT SINKING

s al se s plugged . Finally the large hole in the v ve gment passing the feeders were plugged simultaneously with long aere s ss i sa ofi flush i t p d plug of wood, the exce be ng wn w th rifi ce s -ir s o the front side of the o , the ca t on cap were b lted on to the flanges and the shafts was rendered dry if the h ri work ad been well car ed out . German tubbing is started from a wedging curb and is as r se is r bolted together built up . When the ock it lf t eacher as as - i so ims ous well wet , under hang ng tubbing is met e i . s employed In th s ca e a wedging curb, faced on the bottom r i i is t and p ov ded w th bolt holes, set jus above the shaft

. to t are bottom The segments are lowered the bot om, and grasped one at a time with a special pair of tongs and raised to the under side of the curb . Each segment is then sus pended by two bolts with long threads and the tongs are removed . The lead gasket is inserted ; the segment is raised to place by screwing up the nuts on the long bolts, and is then bolted up tight . The process is repeated as soon as e ff the shaft has been d epened su iciently . After each ring has u been bolted p , the opening at the bottom between it ro i the and the ck is closed w th plates and wedges, and space behind is ﬁlled with cement grout poured in through in holes the segments . CHAPTER X

E S Cos'rs PER E R oo'r CONCR TE LININ G . LIN A F FOR RECT LA LL P L L L ANGU R, E I TICA , AND QUADRI ATERA SHAFTS

Two types of concreted shafts are to be considered : the l l ni circular or el iptical , with unsupported i ng ; and the r i inf ni r rectangula , w th re orced concrete li ng suppo ted by

b s e buntons lls. steel eam , concret , or wa In both, the con crete is placed directly against the rock walls and an inner i form only is required . From a construct on standpoint s are s the type equally feasible , and the choice depend upon n i the cost . In several cases know to the wr ter a com promise has been effected by shaping the shaft as a quadri lateral with sides formed of circular arcs . For a single compartment air shaft the circular shape i is in every way the most des rable , not only because the circular shaft is cheaper to sink than a square shaft of equal l r rin area , but also because a circu a g of plain concrete is the strongest lining possible with a given amount of material . I i n the case of a shaft w th two or more compartments , the selection of the most economical shape requires some At ﬁrst l e ml calculation . sight it wou d se m that a si p e la rectangu r shaft , surrounded by a concrete wall only thick ni enough to be as strong as the usual timber li ng, would be a is a satisfactory, as well as cheap , shape , but th is not the

. ni case A concrete li ng, even when provided with weep holes , must resist some hydrostatic pressure ; a timber ini h as is . l ng none to res t Furthermore , permanent weep holes are most undesirable ; the concrete should exclude the water entirely, and hence must be designed to bear very great pressure at considerable depth . Just what amount the theoretical pressure is reduced by the adhesion of the 1 29 130 PRACTICAL SHAFT SINKING

concrete to the shaft walls and by the blocking of the ﬁ ssures

. s with grout cannot be calculated In olid rock, where the

IG e F . 59 . Rectangular Concret Lined Shaft

- eﬁ ne water enters in well d d springs , the proper grouting of the springs will relieve the lining of all pressure . In very

U I I F GU R F TAB LE 1 . Q ANT T ES AND COSTS O RECTAN LA SHA T

Depth in feet Total thickness of lining in inches Quantities per linear foot :

ds. Concrete to neat line in cu . y

d . . s Concrete, actual in cu y

Excavation to neat line in cu .

yds. d . s Excavation, actual in cu y Weight reinforcing steel in pounds Costs per linear foot : Forms

d . Concrete at 35 cu . y Excavation (see note R nf s lh ei orcing teel at .

Total .

ni seamy rock , on the other hand , the li ng may have to bear e par tically the full hydrostatic pressure . diff let In order to compare the costs of the erent shapes ,

NOTE . Cost of excavation ﬁ gured on basis of $4 per cubic yard for section containing 1 2 yards per linear foot ; additional excavation at $2 per T s s 1 - c i . 6 r s 12 4 4 2 56 . ub c yard hu , co t of cubic ya d ection X 3 X $ $ These unit costs are for purposes of comparison only and should not be

used for estimating .

132 PRACTICAL SHAFT SINKING ladders and to provide in addition an ample passage for air if the hoistways are temporarily closed .

IG a r te ft 1 . F . 6 Qu d ila ral Sha

Let us assume a minimum thickness of 12 in. of concrete for a water-tight lining ; also that in each case the lining

AB LE 3 UANTITIE AND O T OF UADRI ATERA HAFT T . Q S C S S Q L L S

Depth in feet Thickness of lining in

inches. Quantities per linear foot Concrete to neat line in

ds. cu . y

Concrete actual in cu .

yds. Excavation to neat line in ds cu . y .

Excavation actual in cu .

yds. Costs per linear foot Forms d Concrete at 35 cu . y . “ Excavation (see note ) Total carries the entire hydrostatic pressure ; then the speciﬁ ca tions for the three forms of shafts will be as follows :

R c n ul r Shaft. . 59 . 7 1 f e ta a 0 t. g Fig Two hoistways, X ; CONCRETE LININGS 133

1 f -i i i s irw 10 0 t. one a ay, X Ten nch concrete d vid ng wall

ns s 10 25 ft. in place of bunto . Extreme inside dimen ions, X - 24 0 s . f ft. r . ir 100 s . 8 in. Area a way, q ; total clear a ea, q t Thickness of lining at any point mad e equal to depth of 1 -ft i i i simple beam of 0 . span requ red to susta n hydrostat c pressure at that point . Resisting moment and weight of ’ hns reinforcement calculated by Jo ons formula , factor of l i . safety 3 . (U t mate tensile strength of steel, lbs r i ssi per squa e nch, compre ve strength of concrete in beam, i i i in. i 2500 per square nch . ) Re nforc ng steel set 3 ins de of face of wall . 1 in s r s i i Cost of forms, Table , cludes co t of fo m for d vid ng is l l walls, and therefore greater than the cost in the el iptica shafts . Excess of actual over theoretical quantity of excavation 1 2 -f t . ss is estimated as 5 per cent . for 8 . shaft This exce a s as are incre se with the length of the shaft only, the ends i drilled to l ne . f Fi s . i Elliptical Shat g. 60. Extreme inside d mension , 2 f s f 78 . t 1 7 t. r i l 6 X A ea of a rway, q . Tota clear area, 1 - b 4 f i . 30 s . t. allowing for 0 n untons, q Strength of lining calculated on the assumption that the stress in the elliptical cylinder at any point is equal to that

‘ i l i ua caused in a c rcu ar cyl nder, with a radius eq l to the radius of curvature of the ellipse at the given point; by the ni is same hydrostatic pressure acting upon it. The li ng hi therefore made t cker at the sides than at the ends. hi i i i i To prove t s propos t on, assume the l n ng to be con r l s a st ucted of a number of sma l portion , each the arc of in r circle . The stress each po tion caused by the hydro static pressure of the ﬁ lmof water between it and the rock is ir r i hi d ectly propo tional to the rad us, and the t ckness of each section should therefore be made proportional to the

- as a b . i s. 62 rad u Considering any portion, , Fig , the skew back toward the side of the ellipse is formed entirely by the ni i i adjoi ng portion , wh le the skewback toward the end s formed partly by the adjoining portion and partly by the 134 PRAC TICAL SHAFT SI NKING

b o indeﬁ ni l rock . If the num er of circular p rtions is te y i increased , the unbalanced end thrust of each w ll be taken

up by the irregularitiesof the rock . m s Ulti ate compre sive strength of concrete , 3000 lbs .

r r t 3 . pe squa e inch ; fac or of safety , Excess of actual over theoretical excavation assumed as

l . 12 per cent . for sma lest section As the length of the shaft

does not vary , this excess is constant . 1 ua rilateral Shaft. . 55 . 6 Q d Fig Inside dimensions,

i . 2 24 ft. 8 n f 3 t. A X Radius of ends and sides , rea of

4 ft - 9 . 1 i . irw s . n a ay , q Total clear area , allowing for 0 2 4 f s s . t. bunton , 9 q

FIG . 62

For calculating stresses , sides and ends are considered

as 4 - f portions of a 6 t. circular cylinder . Ultimate compres n t 3000 . r sive strength of concrete, lbs per squa e i ch ; fac or of

3 . safety, Excess of actual over theoretical quantity of excavation e 1 2 assum d to be per cent . for minimum length and to e increas with the length . M th s f r s e od o Wo king. The easie t way to concrete a ﬁ nish s i t shaft is to ink ng , then s art at the bottom and build

up . Unfortunately this is feasible only for comparatively s shallow shafts in hard dry rock , and , ordinarily, successive t leng hs of lining must be placed as the shaft deepens, to t s c ff protec the side and ut o feeders of water .

136 PRACTICAL SHAFT SINKING

i ix . i 4 f . mm t i ed ately in front of the m er When concret ng , two men stand on the platform , one on either side the empty bucket is hoisted slightly above the platform level, is grasped

FIG . 63 . Lowering and Placing Concrete by the two men and swung in under the discharge chute of i ﬁ lle the m xer, and is then lowered . When d it is hoisted slightly, swings out over the shaft and is steadied by the men on the platform before being lowered . CONCRETE LININGS 137

B y working as outlined above with a good organization 12 1 5 one- r s it is easy to place or half ya d batche per hour, and a shaft lining containing as much as 6 yds . of concrete per linear foot can thus be placed at the rate of more than a ur as s as i is foot an ho about fa t t mber . It the time s required to construct the foundation platform, to et the rms n se ni one fo , and to con ect a new ction of li ng to the above it that makes the process slow . Foundation platforms must be built and closures must s d be made ; time can be aved only by re ucing the number . sec Plenty of forms should therefore be provided, and the

as ss . r tions made as long po ible The design of fo ms, both as ﬁ nish i regards strength and and facil ty of erection, demands careful consideration . h Forms. The writer as had experience with three

s s. ﬁ rst is s w type of form The , cons ting of wooden labs, as

l ni 1 7 33 ft. l e used for i ng a X el iptical shaft at Tug Riv r, En ineerin ews a. N W. V 7 Th ( g g , November , e

2- slabs were made of in. vertical lagging planks nailed top 2 12 i n. . f and bottom to double X centers They were 5 t. 8 s i high, and slab made up a complete r ng . These forms made a satisfactory wall, but were heavy and were greatly damaged by moving . Eight to ten hours were required to set i i shift one r ng ; the work was d vided into two s , one s i s ss ett ng form and one concreting, so the progre made was

f . only 5 t per day . s s s The second type , con isting of steel lab , was used on i several waterway shafts on the Catsk ll Aqueduct . These l 14 ﬁ h s ft. 6 in. nis ed i hafts are circu ar, about in d ameter, an l d a perfect y smooth surface is required . The slabs are

ft. 5 high and are made four to a ring . Forty feet of forms were provided for each shaft . Two rings were erected at a ti i i me , the concrete be ng tamped and spaded w th long a l new s i h nd ed tools , and when it was po s ble to erect and ﬁ ll tw i o rings in twelve hours . W th use the forms become ifﬁ cult : s more d to set the progress, including platform and 1 i u 0 ft. . clos res, averaged per day A pa r of wooden key 138 PRACTICAL SHAFT SINKING

is i i i s in e ri blocks prov ded at oppos te jo nt ach ng . These r s are chopped out to elea e the forms. Af s l i ﬁ nishe ter a ection of in ng is d , the steel slabs are usually left in place until the next section is ready and then r moved down , a ing at a time . If the section to be concreted a ai e rms i a is longer th n the av labl fo , a work ng pl tform may be suspended below the forms with ropes and the slabs ff taken o at the bottom and moved up . The slabs should always be cleaned and oiled before being used again . i -i — The th rd type consists of angle ron rings spaced 4 ft.

- centers and lagged with vertical 2 in. plank . Wooden ar l r e . e r s nailing st ips bolted to the ang es Thes fo m , e i to ms although they mak a surface nferior the steel for , are cheaper and easier to place . One ring at a time is set and ﬁ lle i ﬁ v e d , and by work ng continuously four or can be

— s. completed in twenty four hour These forms are removed , taken to the surface and cleaned after each section of lining

is fi nished . i Placin . g Concrete should be m xed wet , even though s in considerable water is pre ent the shaft, and should be thoroughly spaded next the forms . Springs of any volume appearing in a section that is to be lined should be taken care of in advance of the lining : this can be done by drilling - r a hole into the water bea ing seam, inserting a pipe long i enough to carry the water out into the shaft , and caulk ng All s the around the pipe . spring should be piped through 30 . 6 forms into the shaft before concrete is placed , Fig , for if this precaution is neglected a very slight inflow may accumulate enough head to disrupt the green concrete and w i i ll cave in the forms . The r ter has known th s to actua y is ft. l happen and has had to dig out about 80 sq . of ining d placed in this way by the water from one tiny spring . r ! i G outing. The drainage pipes should be prov ded at the inner ends with sleeves set flush with the face of the wall . If the concrete has been properly placed and too much dr water has not been encountered , the shaft can be made y ro by plugging the sleeves . If however, the concrete is po us,

See Appendix A.

APPEND IX A

G TS 4 24 NEW Y ROUTING SHAF AND , ORK CITY AQUEDUCT

SHAFT 4

SHAFT 4 is concrete—lined circular shaft sunk through the

Fordham Gneiss near Jerome Park Reservoir . The depth ﬁ ni hed di to tunnel invert is 242 ft. ; the s ameter of the concrete lining is 14’ and the effective average thick ness of the lining in normal rock is Sinking progressed without incident on the one drilling and two mucking shift plan until a depth of 149 feet was reached ; in the ﬁ rst round drilled below this depth clear water was found

in four of the thirty holes . The rock was solid and each hole was plugged with a wooden plug wrapped in sacking as

soon as the bottom was reached .

It was thought that the water might be only a pocket , so after a proper pump had been placed one of the plugs

. was d was removed Pumping continue for two weeks , during which time the upper part of the shaft was lined and A ﬂ appliances formgrouting obtained . s the ow was not appreciably di inished , it was then decided to grout the - r water bea ing crevice through the drill holes . i The grout m xer, which was of the air stirring type d e m standard on the aque uct , was lower d to the shaft botto to and coupled the air line , and was then connected succes iv el s y to the various wet holes . In order to make connec of 2- 3 tions , pieces inch pipe feet long with standard threads at one end were given a gradual taper at the other ; as soon as a plug was drawn from a hole the tapered end of the i i i p pe was wrapped with sack ng and dr ven in tight , and a

2- inch stop cock screwed on. The mixer was attached to s the holes by a heavy hose . The ﬁ rst series of holes wa 140 APPENDIX A 141 grouted in one shift ; the next day more holes were drilled i and more clear water met w th , and grouting was resumed 12 an that night . After hours the holes refused to take y di i 24 e s . more grout , and op rations were cont nued for hours Regular sinking was then resumed and no more water was 200 s met for a week . About sack of neat cement were used in blocking this ﬁ ssure. At a depth of 181 feet the water was again found in the

. h sump holes , and grouting was once more necessary T is time the water was heavily charged with sand and pieces of disintegrated rock the rock around the collars of the drill holes was seamy and it was harder both to make good connections and to force grout into the holes after the con nections were made . Grouting was nevertheless persisted in and in three weeks 130 holes from 10 to 20 feet deep were 50 drilled in the shaft bottom , and over cubic yards of grout (mostly neat cement) was forced into the ﬁ ssures at pres 24 sures up to 0 pounds per square inch . Almost e very hole drilled met some water, and the usual procedure was

fi v off to drill e or six holes , grout them , lay a shift or two fi v e to permit the grout to set , and then to drill or six more in holes . The depth at which water was met gradually ed to creas , and it was therefore possible sink four feet during the three weeks of grouting . The leakage over the 85 n shaft bottom , however , gradually increased to gallo s a minute . At the end of this period the shaft bottom was so thoroughly perforated that there was no sound rock left dr to to ill into and , after an unsuccessful attempt stop the leakage with a concrete blanket , sinking was resumed . It was found in passing through that the disintegrated area 1 5 was a band varying from to feet in width , circling the 10 a shaft , feet higher on the e st than on the west side and twisted and folded in every direction . Below this was solid and perfectly sound rock . The sand was compacted so thoroughly by the pressure 142 APPENDIX A to which it had been subjected that it showed no tendency flow to wash out , and the into the shaft did not appreciably increase . a 10 e be s After exc vating fe t low into the olid rock , the shaft was concreted ; a special section with a minimum of 24 s d 20 e i inche of concrete was place for fe t , extend ng into l bo . the so id rock a ve and below Reinforcing steel , con s i 1 - s 24 r ist ng of inch rod , inches apart , ve tically and hori zontall was a 18 s y, pl ced inche from the face to prevent cracking . The disintegrated area was fi rst lined with thin sheet iron and the water was led through the forms before r h conc eting . The space back of t is sheet iron was packed with rock . Five days after concreting the holes were plugged , and the gauge showed 77 pounds per square inch pressure back of the lining . The leakage through the concrete after the holes were plugged was only one or two gallons per minute . When the concrete had set for a month this leakage was entirely cut off by grouting the holes .

SHAFT 24

Shaft 24 is of the same general construction as Shaft 4 and penetrates blocky and seamy granodiorite for its entire — — 2 A 76 to 69 . t depth in the rock , Elevation Elevation intervals horiz ontal seams were encountered generally inch to inch thick which were fi lled with fi nely crushed flo rock that allowed water to w into the shaft , usually in e only one point of the seam . As the s ams were encountered holes were drilled into them 2 or 3 feet deep wherever there was any leakage and when the shaft was c oncreted these holes were fi tted with grout pipes and were grouted . No great e - 221 quantity of water was met with until at El vation , MO while drilling a round , a flow of gallons a minute was

r . t st uck , all the water coming out of one hole This wa er was under the full hydrostatic pressure due to the head and ’ ﬂooded the shaft . After about a week s delay , in which

APPEND I X B

SEV ERAL of the shafts of the City Aqueduct on the lower east side of Manhattan Island and in Brooklyn were sunk through great depths of water-bearing sand by the pneu

The n r z mat is t o . asso s a e 1 ic ca son me h d c i of two si es, 5 feet 4 i and 1 e in iamet and 2 e and 3 i nches 8 fe t d er, f et feet th ck res e t and are a i ein rce c p c ively, he v ly r fo d with verti al and z At o hori ontal rods . the b ttom of each a heavy steel shoe to n r inf r is imbedded form a cutti g edge . The vertical e o c in r at ed e oo n g rods a e tach to the sho . The r f of the worki g chamber is formed by a heavy reinforced concrete deck O in to c the air for man with two pen gs, whi h shafts the lock and for the material lock are connected . a ﬁ rst a and imb E ch shaft chamber was . exc vated t ered r n and i square to about the g ou d water level, the ca sson was then started from the bottom of the chamber and built up r n i ee e u e to the full height befo e si k ng . St l forms wer s d r ro co e 60 fect th oughout . The deepest caisson p j t d over above the ground before sinking was started .

- . tifi Excavated material was handled by a s leg derrick . a The caisson was loaded with pig iron , and the sp ce between the shafting and the concrete fi lled with excavated sand n n eded in r for additional weight . Si ki g proce rapidly th ee i r a r shifts , at one of the shafts rock be ng e ched th ough n fi 55 feet of sa d in v e days . The most diffi cult part of the operation is the sealing s o air of the cais on into the r ck , so that the can be safely “ taken 0 11 . To accomplish this the ledge is leveled oh and e ss the rock excavated for s veral feet , the cai on meanwhile i t be ng suppor ed on timber posts . The rock is then thor u i air - - r o ghly cleaned w th high pressure , a one to two morta collar is built around the shaft of an inch back of the 144 APPENDIX B 145

o ed s uter ge of the shoe , and the post are then shot out , allowing the caisson to sink through the collar into its ﬁ nal

Spi ced

Comressed Ai p r Caisson Append ix B

is position . The space between the collar and the caisson then grouted through pipes previously set in the collar .

148 INDEX

ia 9 . t es 120 Drill, d mond, Hi ch , .

70 71 . t t rs 1 1 22 e 9 1 . hand , , Hi ch imb , , es and n t n st a r t s u 20. Drill hol , depth i clina io , Hoi ing ppa a ,

8 6 . i 2 6 9 nes 20 23 4 . , eng , , ,

n n s 75 . n 1 1 76 e s 6 . Drill mou ti g , , Hord inking,

70 7 . st e 3 o s 22 . e l , , H ok ,

i 76 . os 78 . Dr lling frame, H e,

u 25 . s 85 . D mmy, Hydraulic jack , 21 22 u . D mp car, , n 2 a 67 . n e t 18 . Dy mite , , I j c or, w 30 . tha ing,

n 97 . Ki d , - hol st 4 24 . i a ro rn ess 7 Electric K nd Ch ud n bo i g proc , 9

2 2 . t 7 9 102 . ligh , , 1 1 1 ll s a 3 33 . E iptical h ft, , 2 35 1 1 . nn st s End plate , , Lackawa a eel heet piling , 20 2 24 s s 3 . a n 36 1 22 . Engine , hoi t, , , L ggi g , ,

i 62 . s nt 1 03 . Excavat ng lock, Len ceme ation, 60 . e 75 . Excavation under air, L yner drill , 2 — os es . 1 7 1 1 0 7 . Expl iv , Lifting water, i s f s 1 1 — 1 8 39 . Lin ng for ha t , n 29 80 . t t 73 . Fan , , Li tle gia drill , - 1 8 . i 1 e oo 6 . F ed pump , L k ng through, 1 e 8 . Fe dwater heater, and t 1 . 88 . Fire wa er excavating, Mammoth pump, r 35 36 - . Man 60 . Fi m earth , , lock ,

41 . n 1 e 35 . Fore poling, Mixer, co cr te, te 1 7 1 1 s 3 38 . 05 . Form , concre , , grout ,

93 . ss 98 . Freezing period , Mo box , ss 35 1 — M o 9 96 . t t. e 95 . Freezing proce , , L okou fr ezing,

24 - as . n t t 2 G o 5 . engine, N ro a ing rope,

67 . Gelatin , 27 t n n s 134 Generator, Opera ion of co creti g haft,

86 . 1 t 36 . Grab bucke , 2 1 1 38 . 05 ss 6 . Grout , , pneumatic cai on, 1 05 . s s a mixer, inking h ft , 1 06 . tank , i 2 s 25 . n 1 2 Guide , Pack g, .

2 v 40 . Gunpowder, . Pile dri ing, 40 Pile hammer, . H ll 1 7 1 1 1 and dri 8 0. , Piping, , , t ’ 1 n s 6 . t s 3 5 . Hangi g bolt , Plan , contrac or ,

ni L 97 st of 32 . Ha el ueg, co ,

1 of 32 . s 7 . Hammer , location ,

— si i 1 6 32 . 43 . Hay , for nk ng, - 2 — 22 n t ss 4 5 — 3 . 0 . e 9 63 Head frame, P euma ic proc , ,

1 i f . r n . o 60 63 Histo ical me tion, lim t , , INDEX 1 49

n t asso 59 . o s t e 42 P euma ic c i n, Skin t kin imb r, .

h . l Poetsc 91 73 . , Slugger dri l, 4 — 2 . s S r n 36 65 . Poling board , oft g ou d , 1 — 0 . iﬁ a i ns 1 se 3 S ec c t o 3 5 . Powder hou , p ,

rma 16 . S ee s n ss n 47 P i ry power, p d of i king cai o , .

r ess s aisso 4 . n 1 7 r 8 83 . P ogr , inking c n , i ock, , i in 0 1 8 8 . s 83 5 . ink ng rock, , , Spoil,

c s 9 . St s e a 40 . Pro p t hole , eam h mmer, 1 2 ls 1 . t St ose 78 . Pu ome er, eam h , 5 121 un s 3 . t t ee s es 39 . P ch block , , S l hee pil ,

‘ 107 1 1 - s s 3 . t n air t ess 6 . Pump , inking, , S raigh li e compr ors, 2 ” — 1 107 1 7 . t t 62 Pumping, S raigh through air lock, . u 67 S mp, a s 1 2 1 a r a 3 34 . 1 es 7 3 . Qu d ilater l h ft , , Suppli , , — i s 34 60 65 . r 33 65 . Qu ck and, , , Surface g ound,

s 4 n t 2 1 1 2 c h ft , ~ s 30 3 . Tamara k a Recta gular haf , , ,

w y t , 30 . a e 27 . Tha ing d nami e Rehe t r, s f 1 b , u y O , 8 e t 44 33 . Tim er ppl Re nforcemen , , er ﬁrm b t 35 . s 67 . Tim ing ear h , Reliever , in e n s n rock 1 1 94 24 Rhe r usse n 90 . p colliery i ki g, 80 “ un , e J 96 . gro d Ri mer, it n t 1 21 , 6 s . Time lim Ri g imber , TOO!r 31 s 6 . oom, Ri k of water, T0 0 15 f s n 1 g, 3 ss 44 . or i kin Rondout cai on , s syst 1 1 7 e 105 . Tom on em , c mentation,

ds 76 . e Tripo . Rop , n 12 u s 5 . T bbi g, Engli h,

ess 99 . o 6 7 for boring proc , 8 8 . Sack b rer, , er 1 2 22 . 8 afet . G man S y hook, 2 9 . Saw ,

n 8 ° ss t 1 Undergrou d water ea 5 63 . S ling cai on o rock, , , Underhan mtubbm 1 2 g g g, 8 ’ s s of 52 57 . Seal , detail , ,

26 ° Secondary bower, t 79 . Ven ilation,

S dnll 73 . ergeant ,

e es 37 38 . s 79 . Sh et pil , Wage , 4 S s s of . t 1 21 35 . haft , depth , Wall pla e, , f 2 s s s s o 3 . t s 6 1 1 . ize and hape , , Wa er clau e, ,

75 . t t 4 1 1 s 7 . Shaft bar, Wa er hoi , , 1 — 1 s 1 8 39 . t s f 33 . Shaft lining , Wa er in ur ace, i difﬁ cult ri s ses 75 . Shaft ink ng in ca Water Leyner d ll ,

— - 63 6 5 . of 1 07 1 1 6 Shield method , Water, pumping , . 7 ri 1 5 S ts . 8 s 109 . hif , Water ng , , 4 4 1 1 es 5 8 63 85 . 7 . Sho , , , , winding, S — — 1 2 1 2 ss 3 . 85 91 . es 7 inking drum proce , Wedg , , 1 1 1 1 in s 07 3 . 2 7 . Sink g pump , , Wedging curb,

— 66 84 . t s t Conisboro 1 1 2 . in rock , We inking a , — 1 1 s 33 65 . e 6 . in urface, Hord n,