DOCSLIB.ORG

Core Bits Are Classifi Ed According Figure 1

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Core Bits Are Classifi Ed According Figure 1 OCEAN DRILLING PROGRAM www.oceandrilling.org Scientifi c Application Extended Core Barrel (XCB) (see the XCB tool sheet) (both sys- A core bit (Figs. 1, 2) is a drilling Cutting shoe tems use the same BHA), tool with a hole through the center that removes sediment rock and II. Rotary Core Barrel (RCB) (see allows the core pedestal to pass the RCB tool sheet), and through the bit and into the core III. Advanced Diamond Core Barrel barrel. The Ocean Drilling Program (ADCB) (see the ADCB tool (ODP) employs different coring sheet). systems and bits to obtain continu- ous cores in all types of oceanic Bottom-Hole Assembly sediments and igneous basement. Operation The BHA for each coring system Once a coring system is selected is slightly different, but in gen- based on the expected lithology, eral consists of a primary core bit, the engineer determines which outer core barrel (OCB), short type of core bit to use. As coring sub assembly, and drill collars. conditions change, the coring bit The OCB supports the wireline A can be changed in an attempt retrievable inner core barrel, which to improve the recovery and rate Cutting shoe receives and carries the core. Drill of penetration with that coring collars are heavyweight pipes that system. The type of bit used apply weight to the bit on the depends on the expected lithology bottom of the OCB. The BHA is and past bit performance in the run on the drill pipe string, which area or in a similar lithology. Once is rotated at the surface to drive a bit is removed, it is “graded” the bit (except the Motor-Driven (i.e., it is examined to determine Core Barrel [MDCB]) and advance wear on the cutting structure, the BHA (see the BHA tool sheet gauge, bearings, etc., based on for more information). The MDCB industry standards) to optimize and Pressure Core Sampler (PCS) coring performance. are compatible with the APC/XCB BHA. Coring System Bits B There are three coring systems. Core Bit Types Each uses different bottom-hole Core bits are classifi ed according Figure 1. A. APC/XCB four roller cone assemblies (BHA) and types of core bit with an APC cutting shoe. B. APC/ to the cutting structure and type of bits: XCB four roller cone core bit with the bearings. There are fi ve basic types XCB cutting shoe. I. Advanced Piston Corer (APC) of bits used by ODP based on (see the APC tool sheet) and their function or structure: drag, inner core barrel (e.g., APC [Fig. temperature probes; and log- 1A], XCB [Fig. 1B], MDCB, and ging tools, which can pass PCS tools). The shoes on the inner through the bit throat without core barrel protrude below the requiring a trip to remove the primary roller cone bit and trim bit or drop it; therefore, coring the formation to core size. In con- and logging operations can be trast, the primary core bits in the resumed without a trip. RCB (Figs. 2, 3) and ADCB systems APC/XCB Specifi cations cut away most of the formation Maximum inner core barrel length: to create the core (i.e., there is no 9.5 m shoe). ODP most commonly uses a four roller cone type bit. APC/XCB bit throat diameter: 9.652 cm (3.80 in.) I. APC/XCB System APC shoe throat diameter: Core Bits 6.197 cm (2.440 in.) Tool Operation XCB shoe throat diameter: Figure 2. RCB four roller cone bit. The APC/XCB coring system can 5.872 cm (2.312 in.) use three types of bits for coring APC/XCB Typical Operating scraper, abrasive, roller cone, and soft to fi rm sediments: hammer. Ranges 11⁷/₁₆ in. four roller cone bit with 1) Formation Drag-type bits have a fl at chisel- tungsten carbide chisel teeth like surface to plane away soft (Fig. 1), APC: sediments ranging from soft formations (i.e., clay and chalk). to fi rm silts/carbonates/chalks/ 10¹/₈ in. PDC “anti-whirl” (Fig. 4) clays. Polycrystalline diamond compact bits, which are rarely used, or (PDC) bits use multiple tungsten XCB: fi rm to moderately fi rm lime- ¹ ₈ carbide studs with artifi cial dia- 10 / in. tungsten carbide blade stones, claystones, dolomites, and mond cutting surfaces in a claw- “drag” bits, which are also rarely with limited penetration in chert or like scraping action to remove used. basalt. soft formations (e.g., clay and Design Features and Benefi ts chalk) up to hard claystone and 2) Depth Range 1) Formation Compatibility limestone. APC: limited by piston core barrel Diamond bits use either surface-set APC/XCB bits are compatible with penetration in stiff or laminated or impregnated diamonds to sediments ranging from soft silts, fi rm/soft formations (i.e., to abrade (i.e., sanding-like pro- sands, and sticky clays to moder- “refusal”) and by wireline overpull cess) hard formations like shale ately fi rm limestones, claystones, to retrieve the core barrel (~100– or basalt. and dolomites. 300 mbsf). XCB: limited by core shoe survival Benefi t: One bit can core a wide Roller cone bits rotate cone-shaped in hard formations (typically used range of sediments without a rollers encrusted with teeth to from APC refusal depth to ~500 trip to change bits. remove soft to hard formations mbsf). through a combination of scrap- 2) Large Bit Throat ing and crushing processes. 3) Mean Recovery The APC/XCB bit throat has a Hammer bits use percussion to APC: ~100%. 3.80-in. opening. crush the hard rock around the XCB: ~55%–75% in sediments and core. Benefi ts: The APC/XCB bit is com- ~15%–35% in basalt. Not recom- Smaller bits called “shoes” are patible with the PCS and MDCB mended for penetration in basalt screwed onto the bottom of the coring shoes; water samplers; other than to sample basement. Hycalog Threads cannot be used in cal bit release to permit wireline igneous rocks. The logging. Flow Port diameter of RCB to Nozzle Benefi t: WSTP and DVTP tools can roller cone bits is 9⁷/₈ Stablizer Pads be run through RCB bits so no in., and the diameter TCI Wear Buttons Cone Arm time is lost for bit trips. on Shirt Tail of PDC bits is 10¹/₈ Nozzle in. Core Guide 2) Rugged Design There are four classes TCI Cutters The four cone-arm segments are of 9⁷/₈ in. RCB four Armored Recessed welded together in the throat area Grease Reservoir Jet Nozzles roller cone bits (Fig. and are armored (faced with hard Throat 5) with different Roller Cones nickel-chrome) on the leading cutting structures edge and upper arm areas. designed for differ- ent formation types: Benefi t: Reduces the chance of cat- astrophic cone-arm failure while Figure 3. Schematic of the four roller cone core bit C-3 bits have long drilling with heavy weight on bit used by the RCB coring system. extension chisel in hard and abrasive formations. teeth and are used in 4) Rate of Core Recovery soft sediments, 3) Ductile Teeth Depends on water depth (i.e., C-4 bits have medium extension The bit teeth are made with a wireline time) and formation. Pen- chisel teeth and are used in fi rm fi ner-grained tungsten carbide to etration rate usually slows with to hard sediments (e.g., dolo- increase tooth ductility, and the depth. mite and mudstone) and limited teeth are pressed into smaller holes APC: ~28.5–9.5 m/hr. upper basement, using greater force. XCB: ~19.0–4.5 m/hr. C-7 bits have short extension coni- Benefi ts: Reduces tooth breakage cal teeth for coring/drilling hard 5) Rate of Penetration and loss due to rough drilling in sediment and igneous base- Depends on rock properties. Pen- ment, and etration rate usually slows with C-9 bits have short exten- depth. sion hemispherical teeth APC: averages ~70–30 m/hr. for coring/drilling very XCB: averages ~30–12 m/hr. hard igneous basement. Limitation Design Features and Recovery is poor in laminated fi rm/ Benefi ts soft (e.g., chert/clay) or granular Flow sediments (e.g., sand, fractured 1) Tool Compatibility Ports Diamonds rock, or rubble). Nozzle RCB bits have a 2.312-in. Flow opening through the bit Channels II. RCB Core Bits throat that enables the Tool Operation Water Sampler Tempera- The RCB coring system typically ture Probe (WSTP) and the uses roller cone type bits (Fig. 2) Davis-Villinger Tempera- PDC Cutters for fi rm sediments to very hard ture Probe (DVTP) to be PDC Core Bit Surface Set Diamond igneous rocks. PDC RCB bits (Fig. run through the bit in fi rm Core Bit formations without hard Figure 4. Side and bottom view schematics 4) have been used occasionally in of PDC and diamond bits. The PDC bit is used fi rm sediments, as they core faster layers. The RCB bit must be in friable lithologies (e.g., limestone or clay- and can last longer under the right dropped with the mechani- stone). The surface set diamond bit is used conditions; however, PDC bits with sediments. fractured rock and reduces tooth 7) Bit Deplugger losses at high temperatures. A bit deplugger can be run in an attempt to remove 4) Recessed and Armored coring debris that can become Lubrication System jammed in the throat of the C-3 Long C-4 Medium The cone bearing has a pressure- bit. The 2.25-in. deplugger Extension Tooth Extension Tooth (soft formations) (medium firm formations) compensated grease reservoir that nose extends through the bit is recessed and covered with a throat and bit cone core trim- steel plate.
Load more

Recommended publications
  • UNIFORM STANDARD SPECIFICATIONS for PUBLIC WORKS CONSTRUCTION
    UNIFORM STANDARD SPECIFICATIONS for PUBLIC WORKS CONSTRUCTION SPONSORED and DISTRIBUTED by the 1998 ARIZONA (Includes revisions through 2010) FOREWORD Publication of these Uniform Standard Specifications and Details for Public Works Construction fulfills the goal of a group of agencies who joined forces in 1966 to produce such a set of documents. Subsequently, in the interest of promoting county-wide acceptance and use of these standards and details, the Maricopa Association of Governments accepted their sponsorship and the responsibility of keeping them current and viable. These specifications and details, representing the best professional thinking of representatives of several Public Works Departments, reviewed and refined by members of the construction industry, were written to fulfill the need for uniform rules governing public works construction performed for Maricopa County and the various cities and public agencies in the county. It further fulfills the need for adequate standards by the smaller communities and agencies who could not afford to promulgate such standards for themselves. A uniform set of specifications and details, updated and embracing the most modern materials and construction techniques will redound to the benefit of the public and the private contracting industry. Uniform specifications and details will eliminate conflicts and confusion, lower construction costs, and encourage more competitive bidding by private contractors. The Uniform Standard Specifications and Details for Public Works Construction will be revised periodically and reprinted to reflect advanced thinking and the changing technology of the construction industry. To this end a Specifications and Details Committee has been established as a permanent organization to continually study and recommend changes to the Specifications and Details.
    [Show full text]
  • Slope Stability Reference Guide for National Forests in the United States
    United States Department of Slope Stability Reference Guide Agriculture for National Forests Forest Service Engineerlng Staff in the United States Washington, DC Volume I August 1994 While reasonable efforts have been made to assure the accuracy of this publication, in no event will the authors, the editors, or the USDA Forest Service be liable for direct, indirect, incidental, or consequential damages resulting from any defect in, or the use or misuse of, this publications. Cover Photo Ca~tion: EYESEE DEBRIS SLIDE, Klamath National Forest, Region 5, Yreka, CA The photo shows the toe of a massive earth flow which is part of a large landslide complex that occupies about one square mile on the west side of the Klamath River, four air miles NNW of the community of Somes Bar, California. The active debris slide is a classic example of a natural slope failure occurring where an inner gorge cuts the toe of a large slumplearthflow complex. This photo point is located at milepost 9.63 on California State Highway 96. Photo by Gordon Keller, Plumas National Forest, Quincy, CA. The United States Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race, color, national origin, sex, religion, age, disability, political beliefs and marital or familial status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program informa- tion (Braille, large print, audiotape, etc.) should contact the USDA Mice of Communications at 202-720-5881(voice) or 202-720-7808(TDD). To file a complaint, write the Secretary of Agriculture, U.S.
    [Show full text]
  • Geotechnical and Pavement Engineering Report Thorp Prairie Road Evaluation and Design Kittitas County, Washington
    GEOTECHNICAL AND PAVEMENT GEOTECHNICAL REPORT ElliottENGINEERING Bridge No. 3166 REPORTReplacement Thorp PrairieHWA JobRoad No. Evaluation 1996-143-21 and Design Kittitas County, Washington HWA ProjectPrepared No. for2012-105-21 ABKJ, INC. Prepared for PacifiCleanApril Environmental 4, 2003 LLC February 1, 2013 TABLE OF CONTENTS 1.0 EXECUTIVE SUMMARY ..............................................................................................1 2.0 INTRODUCTION..........................................................................................................1 2.1 GENERAL.......................................................................................................1 2.2 PROJECT UNDERSTANDING............................................................................1 3.0 FIELD AND LABORATORY TESTING............................................................................2 3.1 FALLING WEIGHT DEFLECTOMETER TESTING ...............................................2 3.2 PAVEMENT CORE HOLES ...............................................................................3 3.3 LABORATORY TESTING .................................................................................3 4.0 SITE CONDITIONS ......................................................................................................4 4.1 SITE DESCRIPTION.........................................................................................4 4.2 GENERAL GEOLOGY ......................................................................................4 4.3 PAVEMENT STRUCTURAL
    [Show full text]
  • Core Drilling of Hot Mix Asphalt (HMA) for Specimens of 4” Or 6” Diameter
    Proposed method and procedure Core Drilling of Hot Mix Asphalt (HMA) for Specimens of 4” or 6” diameter 1. SCOPE 1.1 This method is to establish a consistent method of the use of a diamond bit core to recover specimens of 4 or 6 inch diameter for laboratory analysis and testing. 1.2 The method will require the use of: water, ice (bagged or other suitable type), dry ice, and a water-soap solution to be utilized when coring asphalt rubber concrete. 1.3 Individuals doing the specimen recovery should be observing all safety regulations from the equipment manufacturer as well as the required job site safety requirements for actions, and required personal protective equipment. 2. CORE DRILLING DEVICE 2.1 The core drilling device will be powered by an electrical motor, or by an acceptable gasoline engine. Either device used shall be capable of applying enough effective rotational velocity to secure a drilled specimen. The specimen shall be cored perpendicularly to the surface of pavement, and that the sides of the core are cut in a manner to minimize sample distortion or damage. 2.2 The machinery utilized for the procedure shall be on a mounted base, have a geared column and carriage that will permit the application of variable pressure to the core head and carriage throughout the entire drilling operation. The carriage and column apparatus shall be securely attached to the base of the apparatus; and the base will be secured with a mechanical fastener or held in place by the body weight of the operator.
    [Show full text]
  • Core Drill Core Drill
    DRILLING until the core bit has stopped rotating. Keep the equipment clean - you will find this less of a 309/01 For standard drilling (without dust removal fitted) use Remove the hole-starting aid from the core bit if it was chore if you clean it regularly, rather than wait until the end slotted core bits. fitted before. of the hire period. NOTE: Dust is released in all directions. Drilling Position the core bit (in the guide kerf when the hole- Keep cutting tools sharp and clean. Properly maintained Operating & Safety Guide 309 without a dust removal system, especially overhead starting aid was used) and then press the on / off switch to cutting tools with sharp cutting edges are less likely to bind drilling, is very unpleasant and optimum performance continue drilling. and are easier to control. is not achieved. Overhead drilling without use of dust Allow the vacuum cleaner to run for a few seconds When not in use, store the equipment in its toolbox removal system is therefore not recommended. For dry after switching off the machine in order to ensure that the somewhere clean, dry and secure. coring it is recommended that the dust removal remaining dust is removed. attachment and a suitable vacuum cleaner are always Professional dust removal equipment available for used. from HSS Hire. FINISHING OFF Release the on / off switch on the power tool and slowly DANGER! NOISE AND VIBRATION pull the core bit out of the hole. Switch off the vacuum cleaner if you are using one. HOLD POWER TOOL BY INSULATED GRIPPING SURFACES, Typical A-weighted sound power level: 95 dB (A) WHEN PERFORMING AN OPERATION WHERE THE Switch OFF power supply before unplugging it.
    [Show full text]
  • 204-5 Asphalt Concrete Samples Obtained by Coring
    STP 204-5 Standard Test Section: ASPHALT MIXES Procedures Manual Subject: ASPHALT CONCRETE SAMPLES OBTAINED BY CORING 1. SCOPE 1.1. Description of Test The standard test procedure is used for collecting samples of asphalt concrete by coring methods. 1.2. Application of Test Samples of asphalt concrete collected using the coring method may be used to evaluate various characteristics of an asphalt concrete pavement for construction quality control testing, quality assurance testing and product acceptance testing. Core samples may also be used for research testing purposes. 1.3. Units of Measure The standard core sample diameter for purposes of this test procedure will be 101.6 mm or 152.4 mm. Generally, the maximum thickness of asphalt concrete pavement to be sampled will be 250 mm. 2. APPARATUS AND MATERIALS 2.1. Equipment Portable Drilling Equipment - mounted on a trailer, truck or other similar equipment for transportation purposes. The drill shall be equipped with a source of power suitable for driving the core barrel. The drilling unit will be equipped with a source of air or water supply to cool the core barrel during drilling operations. Core Barrels - which will provide cores as described in section 1.3. Generally thin walled core barrels with surface set diamond cutting edges provide the best samples. Core Retrieval Tool - to extricate cores from the pavement when coring is completed, without causing damage to the cores. Marshall hand held compaction hammer. Gloves or mitts for handling dry ice. Date: 1994 12 09 Page 1 of 6 Standard Test Procedures Manual STP 204-5 Section: Subject: ASPHALT MIXES ASPHALT CONCRETE SAMPLES OBTAINED BY CORING An insulated container in which cores can be placed and maintained at a cold temperature.
    [Show full text]
  • For Use on Any Core Drilling Machine
    2013-2014 1 .com QR CODES Order On-Line & SAVE! Pages in our catalog have these QR codes – if you scan them with your smart phone they will take you directly to that product page on our website, showing specs, features, benefits, videos, this will give you the best source of information and purchasing, and specials anywhere! SOCIAL MEDIA THAT ACTUALLY MEANS SOMETHING TO YOU! You’ll actually GET something from our Sites! Not just your typical social media Promoting – These sites ARE worth your time! Save Money! Take advantage of Specials ONLY found HERE! Stay connected and get your new info easily - Learn How to on our Video’s! Linkedin FaceBook Twitter YouTube • Easy to use website – Find your product fast! • Wide variety of Choices – Compare Prices and Products! • Get order confirmations, tracking numbers • Pay on our SSL Secure checkout or use PAYPAL 2 3 CONTENTS DIAMOND SAW BLADES / SAWING EQUIPMENT DIAMOND CORE DRILL BITS HIGH SPEED BLADES .........................................................................6 - 7 DRY DRILLING CORE DRILL BITS ...................................................34 - 35 HIGH SPEED SAWS ...........................................................................8 - 9 VACUUM DRY DRILLING CORE DRILL BITS ..................................36 - 37 MASONRY SAW BLADES ...............................................................10 - 11 WET DRILLING HAND HELD CORE DRILL BITS .............................38 - 39 MASONRY SAWS ...........................................................................12 - 13
    [Show full text]
  • Drilling Manual Jn Dunster
    NORTHERN TERRITORY GEOLOGICAL SURVEY DRILLING MANUAL JN DUNSTER Record 2004-007 Northern Territory Government Department of Business, Industry & Resource Development NORTHERN TERRITORY DEPARTMENT OF BUSINESS, INDUSTRY AND RESOURCE DEVELOPMENT Geological Survey Record 2004-007 Drilling manual JN Dunster Northern Territory Geological Survey Northern Territory Government Darwin, 2004 Department of Business, Industry & Resource Development i DEPARTMENT OF BUSINESS, INDUSTRY AND RESOURCE DEVELOPMENT MINISTER: Hon Kon Vatskalis, MLA CHIEF EXECUTIVE OFFICER: Mike Burgess NORTHERN TERRITORY GEOLOGICAL SURVEY DIRECTOR: Richard Brescianini BIBLIOGRAPHIC REFERENCE: Dunster JN, 2004. Drilling manual. Northern Territory Geological Survey, Record 2004-007. (Record / Northern Territory Geological Survey ISSN 1443-1149) Bibliography ISBN 0 7245 7085 3 Keywords: Drilling, core drilling, diamond drilling, drilling problems, RC drilling, slim hole drilling, stratigraphic drilling, wire line drilling, drilling equipment, drilling fluids EDITORS: PD Kruse and TJ Munson For further information contact: Geoscience Information Northern Territory Geological Survey GPO Box 3000 Darwin NT 0801 Phone: +61 8 8999 6443 Website: http://www.minerals.nt.gov.au/ntgs © Northern Territory Government 2004 Disclaimer While all care has been taken to ensure that information contained in Northern Territory Geological Survey, Record 2004-007 is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of its information. The Northern Territory of Australia gives no warranty or assurance, and makes no representation as to the accuracy of any information or advice contained in Northern Territory Geological Survey, Record 2004-007, or that it is suitable for your intended use. You should not rely upon information in this publication for the purpose of making any serious business or investment decisions without obtaining independent and/or professional advice in relation to your particular situation.
    [Show full text]
  • Diamond Core Drill User Guide View File
    User Guide Please observe the following guidelines to ensure a long working life for your Faithfull Diamond Core Bits. Faithfull Diamond Dry Core Bits are suitable for Always ensure that the core bit is rotating when cutting breeze block, brick and soft concrete. entering and exiting the material being cut. They are not designed to cut extremely dense use “hammer” action when using a diamond concrete, engineering bricks or abrasive materials Never core bit, as this is likely to cause damage to both because doing so may damage or reduce the the core drill bit and to your power tool. working life of the core bit. attempt to cut metal or reinforced concrete Diamond Core Bits must always be used with power Never as damage to the core bit is likely to occur. drills rated at between 850 to 1,000 watts, which are equipped with a safety clutch and a variable speed Never allow the core bit to become excessively hot function capable of speeds of up to 3000 rpm. while cutting, and allow a cooling down time Always use the drill at the recommended rotational between cutting applications. speed for the size of core bit being used. Please refer to your manufacturers’ instructions as Speeds of between 1,000 and 3,000 rpm are normal to the maximum core diameter that can be safely for the correct operation of diamond core bits. used with your power tool. ROTARY USE ONLY – Must not be used on Percussion/Hammer mode DO NOT use Diamond Cores larger than 78mm in diameter Operation Hints with SDS-plus drills as this may result in damage to the power tool or SDS adaptor.
    [Show full text]
  • LIGHTWEIGHT 50-METER CORE DRILL for FIRN and ICE Heinrich
    Reproduced from Ice-Core Drilling edited by John F. Splettstoesser by permission of the University of Nebraska Press. Copyright 1976 by the University of Nebraska Press. Copyright renewed 2004 by the University of Nebraska Press. LIGHTWEIGHT 50-METER CORE DRILL FOR FIRN AND ICE Heinrich Rufli, Bernhard Stauffer, and Hans Oeschger Physics Institute University of Bern Sidlerstrasse 5 3012 Bern, Switzerland ABSTRACT The increasing interest in ice-core analyses has made it apparent that new drills need to be developed for coring in Jim and ice. To close the gap between the range of the SJPRE coring auger and that of the CRREL thermal drill an electromechanical drill has been constmcted which will core to 50 m in fim and ice. The drill is suspended from a cable, and consists of a coring system, a driving system and an antitorque system. The drill was tested successfully in Greenland in 1974, where it was possible to drill to 50 m in a few hours. In troduction With the SIPRE coring auger it is relatively easy to drill to 20 m in fim or 10m in ice. Drilling deeper is possible but difficult. Holes with depths between 100 and 500 m have usually been made using thermal drills (Ueda and Garfield, 1969). Attempts have been made to close the gap between the ranges of the two drills by mOdify­ ing the SIPRE coring auger. The modifications consist of an electrical drive for drilling and electrical and mechanical means for raising and lowering the auger. They allow deeper drilling but the equipment is heavier and the drilling is tin,e-consuming because of the need to handle the numerous extensions.
    [Show full text]
  • Development of Smart Boulders to Monitor Mass Movements Via the Internet of Things: a Pilot Study in Nepal Abstract
    https://doi.org/10.5194/esurf-2020-78 Preprint. Discussion started: 8 October 2020 c Author(s) 2020. CC BY 4.0 License. Development of smart boulders to monitor mass movements via the Internet of Things: A pilot study in Nepal Benedetta Dini1, Georgina L. Bennett2, Aldina M. A. Franco1, Michael R. Z. Whitworth3, Kristen L. Cook4, Andreas Senn5, John M. Reynolds6 1 School of Environmental Sciences, University of East Anglia, Norwich Research Park, UK; 2College of Life and Environmental Sciences, University of Exeter, UK; 3AECOM, UK; 4GFZ-Potsdam, Germany; 5Miromico AG, Zurich, Switzerland; 6Reynolds International Ltd, UK 1 Abstract 2 Boulder movement can be observed not only in rock fall activity, but also in association with other 3 landslide types such as rock slides, soil slides in colluvium originated from previous rock slides and 4 debris flows. Large boulders pose a direct threat to life and key infrastructure, amplifying landslide 5 and flood hazards, as they move from the slopes to the river network. Despite the hazard they pose, 6 boulders have not been directly targeted as a mean to detect landslide movement or used in dedicated 7 early warning systems. We use an innovative monitoring system to observe boulder movement 8 occurring in different geomorphological settings, before reaching the river system. Our study focuses 9 on an area in the upper Bhote Koshi catchment northeast of Kathmandu, where the Araniko highway 10 is subjected to periodic landsliding and floods during the monsoons and was heavily affected by 11 coseismic landslides during the 2015 Gorkha earthquake. In the area, damage by boulders to 12 properties, roads and other key infrastructure, such as hydropower plants, is observed every year.
    [Show full text]
  • Geotechnical Characterisation of Landslide Slope-Prone Sediments
    Geotechnical measurements to characterise slope sediments and to identify landslide mechanisms and their impact on ecosystems Doctoral Thesis submitted for the doctoral degree in natural sciences at the Faculty of Geosciences of Bremen University zur Erlangung des Doktorgrades der Naturwissenschaften im Fachbereich Geowissenschaften der Universität Bremen by vorgelegt von Annika Förster Bremen, Juni 2011 Tag des Kolloquiums: 31. Oktober 2011 Gutachter: Prof. Dr. Achim J. Kopf Prof. Dr. Tobias Mörz Prüfer: Prof. Dr. Katrin Huhn Prof. Dr. Rüdiger Henrich Abstract 1 Abstract Submarine mass wasting processes are not uniformly distributed over the world’s ocean. Glaciated margins are also affected as non-glaciated margins including fjords, submarine canyons and river deltas. Observation, monitoring and analysis of the mass wasting processes are of large scientific as well as socio-economic interest due to the hazardous impact of, e.g. landslides on offshore industry installations. Likewise, Tsunamis that are triggered by mass wasting processes, endanger coastal cities and surrounding areas. The distribution of submarine landslides may be controlled by the interaction of morphology, sediment composition, sediment mechanical behaviour (e.g. lowered sediment strength) and external triggers (e.g. earthquakes, sea-level change). In summary, the presented study investigates the mechanics, mechanisms and factors governing slope instabilities of three different submarine landslides sites evolved from active and passive continental margins. Results of geotechnical measurements from both the stable and the failed part of the different landslides were compared to previously published geophysical and sedimentological data. The three different research sites are i) the passive continental margin of Mauritania, NW-Africa, ii) the low seimic and tectonically active Ligurian margin (Southern France) and iii) the high tectonically active margin of the Cretan Sea (Greece).
    [Show full text]