View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Missouri University of Science and Technology (Missouri S&T): Scholars' Mine Missouri University of Science and Technology Scholars' Mine International Conference on Case Histories in (1998) - Fourth International Conference on Geotechnical Engineering Case Histories in Geotechnical Engineering 11 Mar 1998, 1:30 pm - 4:00 pm Study on Mechanism of Caisson Type Sea Wall Movement During Earthquakes Masayuki Sato Tokyo Electric Power Services Co., Ltd., Tokyo, Japan Hiroyuki Watanabe Saitama University, Urawa, Saitama, Japan Satoshi Katayama Saitama University, Urawa, Saitama, Japan Follow this and additional works at: https://scholarsmine.mst.edu/icchge Part of the Geotechnical Engineering Commons Recommended Citation Sato, Masayuki; Watanabe, Hiroyuki; and Katayama, Satoshi, "Study on Mechanism of Caisson Type Sea Wall Movement During Earthquakes" (1998). International Conference on Case Histories in Geotechnical Engineering. 12. https://scholarsmine.mst.edu/icchge/4icchge/4icchge-session03/12 This Article - Conference proceedings is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in International Conference on Case Histories in Geotechnical Engineering by an authorized administrator of Scholars' Mine. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. 604 Proceedings: Fourth International Conference on Case Histories in Geotechnical Engineering, St. Louis, Missouri, March 9-12, 1998, Study on Mechanism of Caisson Type Sea Wall Movement During Earthquakes Mnsaruki Sato Hiroyuki Watanabe Satoshi Katayama Paper No .3 18 Tokyo Electric Power Sen· ices Co .. Ltd Saitam:1 UniYcrsitv Sait:nna UniYcrsitv TokYo ll (l,Japan Un.ma. Saitama :ns. Japan Urawa. Saitama 338. Japan ABSTRACT Model vibration tests under gravity and centrifuge model ribration tests in 50G were performed to investigate the behavior of caisson type sea mill \\ ith reclaimed gronnd below and behind the caisson. In the tests. sliding of caisson occurred only during excitation, which indicates that it is impossible to predict the disphlccmcnt of caisson and the deformation of back-fill ground without taking account of both inertia force of caisson and d~ namic earth pressure_ As for the dynamic earth pressure acts on the caisson. it W<lS found that "·hen input acceleration is srnalL the dymmic earth pressure seems to restrain the movement or caisson and the excess pore water pressure hardly occurs. On the other hand. \rhcn inpnt acceleration is large enough to cause liquefaction. the dynamic earth pressure seems to promotes the mo\ cment of caisson. KEYWORDS caisson type sea waiL reclaimed ground. liquefaction. excess pore \Yater pressnre. dynamic earth pressure. large ground dcfornwtion INTRODUCTION research for the above purpose, arc performed in order to examine the mechanism of movement of caisson type sea wall From t.hn past damag-e of harbor strudurPs. many with reclaimed ground behind it. Besides, centrifuge model eases of large ground deformation sw~h as latt'ral flow vibration tests 111 SOG \-Vere performed to investigate the and snttl(~ment dw: to liquefact.ion aeeompcmying- a behavior of caisson and reclaimed ground just below and larg(~ displaeement. of cnisson toward S(~11 sidl~ wr.rr~ behind the caisson under the same confining pressure as actual found. In recent earthquakes. particularly in Kushiro-oki structure. earthquake (!993 ), Hokkaido Nansci-uki earthquake (!994) and Hyogo-kcn Nambu earthquake (I ')95). such kinds of damages were obscr\'cd in \'arious seaside places. In their MATERIAL FOR MODEL neighborhoods large accelerations or 400gal to 500gal \-vcrc obscrYcd. Howe\·er. in the design of such structures as caisson Gcncrall~-, in shaking table tests, liqucftlction docs not last type sea walls. only the e\·aluation weather the sliding or long hccause the model is so small that the excess pore water caisson occurs or not is performed by applying around 0.1 to pressure disperses too early. Besides, the behavior of ground 0.2 of seismic coc!T!cient. and the c\·;lluation on the amount or model dnring excitatiou becomes difTcrcnt from that of real caisson's sliding is scarcely performed. !!round because of extreme low confining pressure (Towhata et al. I ')!)5). Taking account of the above facts. the ground model From now OIL 111 the aseismic design for airpol1 I;Jcilitics. made of extreme lose sand. for example relativity density less pmycr station facilities on reclaimed islands as \\ell as general than 0 '~'0. is occasionally prepared so that it can shows harbor stmcturcs. the CY<Jlnation on the amount of both sliding negatiYc dilatanc~ cYcn in the low confining pressure. and sctllemcnt of caisson should be implemented. Through MoreoYcr. the e.-.:pcrimcnts with yiscosity fluid which m~1kcs such cyaJuation. \YC can assess "hcther these structmcs can the permeability of soil YCJY' small arc performed frequently. maintain the fundamental function to be safe against earthquakes Based on the past studies by authors (Sato ct al. 1997), hmrc\'cr. it is found that the specimen made ofToyoura sand In this study. model Yibration tests. \-Yhich arc fundamental Fourth International Conference on Case Histories in Geotechnical Engineering Missouri University of Science and Technology http://ICCHGE1984-2013.mst.edu 605 0.4 -~ 1.E-01 --+- torstonal ~ 1.E-02 0 -o-- triaxial :.0 -~ 0.3 IV l ~ Q) '\" p~ ,... G 0:::: ~- l .E-03 (I) ~ E---Q) 0 (I) h.. - E> Q) ~ a. ~~--- .. (I) \ . .......... ~ 0.2 1- - 1- 0% -- .... , l.E-04 '"""'"! C/) o E roo ..... 0 0 t-- b .... I.._. ~--- l .E-05 -...;;;:: 0 '(3 ·------- ()>- 0 . 1 --1-f- f.:-. 0 ~:> lc - lE Q) l.E-06 -- - f---- I 0 - ~ -- ~i () ---- 0.0 I l.E-07 10 100 1000 0 20 40 60 80 100 Number of Cycle, N, DA=5% Fines Content(%) Fig.-1 Uquefaction Strength of DL-clay Mixture Sand Fig.-2 Coefficient of Permeability ofDL-clay Mixture Sand ? 100 '-" Cl) 1 .....~ 80 c: o~~l:JII : i It~ Cl) ·t ...0 Experiment L Q) 60 - ·- ~.' materials {; ~- - - 1 a. .' (DL -clay 20%) ' 40 --1-1- F;f .' -Toyoura Cl) V¥'!,.-Sand ~ 20 r (I) (I) a.IV ............. 0 0 .001 0.01 0.1 Grain Size (mm) 0'""'""' 0. 2mm Fig-3 Grain Srze Distributwn of'lb_voura Sand, DL-clay and Photo-/ Microstructure ofDL-clay (20%) Mixture ,)'and DL-clay ( 10%) Mrxture Sand Model Dcscript ion nm:ed mth DL-clay indicates extremely lower liquefaction strength (F1g. -I) and shows more remarkable tendency of A rigid vessel made of steel plates ha\'ing its inner d11nension. negati\c dllatanC) than those of the specimen made of 100% 200 em long. 65 em "ide, and 45 em high. "as fi '\ed on the Toyoura sand '' ith the sa me relati\'C density as that of DL-clay shaking table. Inside the \'CSsel. the model consisting of a mixed saud specimen. Besides. the specimen made of the DL­ mortar block, front water, water saturated base and backfill soil clay m1xture sand indicates low permeability too (Fig.-2). was installed as shown in Fig.-4. For simplicity, mbblc mound and mbble back-filling of actual structure \verc not considered. DL cia~ l'i non-plastic silt "hich has the grain size distribution and the ''ater lc\'el \\as set at ground surface. sh0\\11 111 fig. -3 The gnlin site distnbutions of Toyoura sand and the nt1:xture of 80% To)Otlra sand a nd 20% DL cl<t) arc Two types of models. the th1ckncss of the sand layer belo" also sho" n in Fig.-3. The microstmcturc of the same mixed b) caisson being lcm and IOcm. were prepared for the tests. The means of microscope is sho\\ n in photo- I. model \\'hich has I em I h1ckncss of sand layer below the caisson (Model-A) is for the case that the caisson stands ou the In this study. the models of not only Toyoura sand but also dense subsoil or on the rock. On the other hand. the case of 20°o DL-clit) mixed TO)Ollnt sand arc prepared for the IOcm thickness of sand layer belo" the caisson (Model-B) e.,penments It IS one of the purposes for us to confirm that the simulate the case that the liquefiable layer ex1sts bclo\\ the cxpenments on the model made of DL-cla~ nuxed sand can caisson a<; obser\'cd in Hyogo-ken Nambu earthquake ( 1995 ). unpro' c 1he problems ment ioncd abO\ c. The sand or DL-clay mixed sand was poured into the rigid box. in ·which the caisson model had been set. by dry pluvwllon. MODEL VIBRATION TESTS Then \Vater was introduced to the soil through the inlet tube at the base of the rigid vessel. Sensors and measurement positions Fourth International Conference on Case Histories in Geotechnical Engineering of the model arc shown in fig.-4 Missouri University of Science and Technology http://ICCHGE1984-2013.mst.edu ( ) 606 Direction of Shaking D Ao.:celerometer (horizontal) 1!1! Ac..:elcromctcr (vertical) [). Pore Pre~sure Transducer 0 Em1h Pressure Transducer ~ ~ IYDT " ~ lit ~ Gap Sen.~or l ' 0 1 \ t t .'i' -------+ fr---+-------~;~) .. __ !," --- i\ Cuisson ' ',)8 Bm.:k fi 11 Sand 30 OA-- I .'1\8 ' OA _\t --·-- <Ls " ' l I Rigid Vessel '' (a) Alodei-A Unit : em r->----"-~ ~.'c'c_j-c~~~~~-_[]__n_I\~·~·L__---Q-----,,r-, --Q------'b-u--;-----] - -,1, Q----------Qa---'1,~9 -- j,__ _____ - :10 Caisson 8 b. J". - . A ' 8 Backfill Sand ' --------DAA,!;"-;c------ , __ ---------"''=---- f----)\''-'___ _L ____ _j • >fj ·-----6~-- ~~-- fl__ ---------- • !', ',' 1 () m G Rigid Vessel n (b) Modei-B Unit : em Fig-4 }o.dodel Conflgra!ion Table-] Experimental Cases Experimental Case Material of Model Expected Level of lnout Motion Rccraimcd Ground 50eal !50eal 400eal Model-A DL-clav Mixture Sand AF-50 AF-150 AF-400 DL-day Mixture Sand - - 131'-400 Modd-13 Sand - - BS-400 150gal and +OOgal of input <lccclcration were applied to the Model Testing and Test C_ils_cs identical model (AF-SO,AF-150 and AF-400).