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International Conferences on Recent Advances 1995 - Third International Conference on Recent in Geotechnical Earthquake Engineering and Advances in Geotechnical Earthquake Soil Dynamics Engineering & Soil Dynamics
06 Apr 1995, 10:30 am - 12:30 pm
Liquefaction Damage of Sandy and Volcanic Grounds in the 1993 Hokkaido Nansei-Oki Earthquake
S. Miura Muroran Institute of Technology, Japan
K. Yagi Chizaki Kogyo Co. Ltd., Japan
S. Kawamura Hokkaido College, Senshu University, Japan
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Recommended Citation Miura, S.; Yagi, K.; and Kawamura, S., "Liquefaction Damage of Sandy and Volcanic Grounds in the 1993 Hokkaido Nansei-Oki Earthquake" (1995). International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. 3. https://scholarsmine.mst.edu/icrageesd/03icrageesd/session03/3
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This Article - Conference proceedings is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics 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]. (\ Proceedings: Third International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, '-'1 April2-7, 1995, Volume I, St.louis, Missouri Liquefaction Damage of Sandy and Volcanic Grounds in the 1993 Hokkaido Nansei-Oki Earthquake Paper No. 3.06
S. Miura S. Kawamura Associate Professor, Dept. of Civil Engineering, Muroran lecturer, Dept. of Civil Engineering, Hokkaido College, Institute of Technology, Japan Senshu University, Japan K. Yagi Engineer, Chizaki Kogyo Co. Ltd., Japan
SYNOPSIS The 1993 Hokkaido Nansei-Oki Earthquake of magnitude 7.8 caused widespread and significant damage in south west area of Hokkaido, Japan. The soil liquefaction was induced at many locations, which resulted in considerable damage to structures, lifelines, and facilities. In order to evaluate their in-situ liquefaction strengths, the site investigation involved the conduct of standard penetration test ( SPT) was performed at several key locations. A series of cyclic undrained triaxial tests was also carried out on soil samples taken from liquefied grounds. Test results showed that the mechanism of increase in the liquefaction strength due to the increase in relative density and the feature of anisotropy in the cyclic deformation behavior of damaged grounds are almost the same with those of clean fine sand such as Toyoura standard sand (Miura et al. 1994). Analysis of liquefaction based on SPT N-value was also performed.
INTRODUCTION (length of about 70m and width of about 15m), ground fissures, collapse of stairs and subsidence of the Hokkaido Nansei-Oki Earthquake occurred at 10:17 road occurred (Fig.2). The outflow volume of soil p.m. on July 12, 1993, in approximately 70km north was estimated to have been about 10,000m 3 • Fig.3 of Okushiri Island, Hokkaido, Japan. According to shows the boring logs obtained after the the Japan Meteorological Agency (JMA), the quake earthquake. From this figure, lakeshore consisting was of magnitude 7.8 and epicenter was located at of loose sand appears susceptible to liquefaction Long.l39.12'E, Lat.42.47'N with a focal depth of from the water table to a depth of about 11m. 34km. The earthquake caused considerable damage in Mizuhori sand: This was sampled from boiled sands Okushiri Island and Oshima Peninsula. In total, 231 at the playground of Mizuhori Elementary School, people were killed by tsunami and landsliding. located on the deltaic deposit of Assabu River. Due Furthermore, soil liquefaction was most prevalent to the hitting of quake at magnitude 6.5 on August in the lowlying area, resulting in extensive damage 8, re-liquefaction took place at the same areas. to roads, river dikes, lifelines, houses and port Houses, roads and agricultural lands were damaged structures, etc. Physical evidences of liquefaction phenomena such as ground fissures with sand-boilings, sand volcanoes ejecting volcanic ashes, and lateral flows with large settlement were seen everywhere around damaged sites. After of this event, the authors conducted the site investigation, and soil samples were taken from damaged and undamaged grounds. A series of *EPICENTER index property tests and cyclic undrained triaxial tests were carried out to understand the dynamic JJA mechanical properties of liquefied grounds, comparing to their SPT N-values.
N SAMPLING SITES Soil samples were taken from 26 sites of 10 locations, which experienced the liquefaction. t Fig.1 shows the sampling sites with the seismic intensities (JMA) and the epicenter. These liquefied sites were classified into 4 categories: 1) coastal plane (including lakeshore), 2) old and current river courses 3) reclaimed land 4) the piedmont of an active volcano (Mt.Komagatake's eruption). Five of soil samples which represent these sites were selected for study and referred ( ) SEISMIC INTENSITY tentatively to as Toya, Mizuhori, Nakanosawa, 0 10 20 30 40 50 Mandai and Mori sands, respectively. The features Km of these sampling sites, which are indicated by enclosing the names with lines in Fig .1, are summarized as follows; Toya sand: The earthquake led to a landslide in Fig. 1 Map showing sampling sites and their Toya Lake, so that disappearance of the lakefront seismic intensities in the JMA scale
193 Piq. 2 Diuppearance of lakeshore and collapse of Fig. 4 Collapse of apron at .Port of Hori whe re staica at toya Lake volc:anie coarse qra.inod soill were encountared
100 ~~~----~~~W?~~-.~~~ ..,..,. ~90 !i80 iii 70 ~60 w 50 ;:40(!) ilj30 offi 20 __ 1 ---r----:: o.. to .. · .6o ~ Voiotf'.la Ull £olo-,~~~o.1o ,--~~o~. ~~~l-j_~~~1o==~ -"....:....:...-' l'8:l ... 0.005 0.05 0.5 5 50 • : Boring 1011$ dtUied llftor lhe eet1hqual i 5 10 50i00 500 b 0.4 NUMBER OF LOADING CYCLES, Nc CfCLIC TRIAXIAL TEST ~ Oc~49kPa , 0.4 .-----r---r------r;:====~ "0 I 0 DA=5% Nc=20 · ; ' / ; ' f= 0 "~"'- ~ ! 11 ~~~R~~~~~~1Hz I 0.3 ....~ .. ·~~~;~~~;; ...... l ...... ·j"· ...... '"l'""""""d(/" "'!"""'"""""t""'"""""' ...... Q..:6. .. Q ...... , ...... ,...... ,J Drc=1 05 Yo J...... 0 (f)T'"'~*0.3 * MIZUHORI SAND [ ! ~; ITJ ; ' CfJv ~ 0 NAKANOSAWASAND! · ~' j ; w<( ~ ~ 1 a: e MANDAISAND ; ~ ; l ~ A & ~ (f) 0.2 1::. MORI SAND 1 ...... !"'"" .. 2' /;r7'4>· :Yo.... 1 cr: 8-0.2 ...... ,...... !"'@.\J~cO!d"""""'t""""""'"""" .. """"""" (() • TOYOURA SAND i ; ! ; t) _o w i¥ / 0 DA(%) ~ : : t-o- a: 0~ f 0.1 :::::i-o 0.1 ~ ------~- -(~; (f) oo ,:, -'-r ,--- - 0 ~~-p~ +~!- : ' b :::::i 5 10 50 100 500 ~ 03~0--4~0--~0~6~~0--~~~~--~~ 0 5 0 7 80 90 100 i 10 120 NUMBER OF LOADING CYCLES, Nc RELATIVE DENSITY, Ore(%) Fig. 6 Cyclic stress ratio versus number of cycles to DA=2%, 5% and 10% for (a) Toya sand and (b) Fig. 7 cyclic stress ratio at Nc=2 0 to DA=5% versus Mand~i sand relative density after the consolidation 195 Table 1 In-situ liquefaction strength estimated by JRA method Site Name DL Mean SPT Drin-situ (m) N-value (%) Toy a 11.5 8 44 0.136 Mizuhori 9.1 7 50 0.122 -5 10 Nakanosawa 3.4 1 21 0.05 Mandai 10.0 8 51 0.210 AXIAL STRAIN(%) Mori 6.1 5 41 0.08 Fig. 8 Time history of effective stress path and table, the relative densities of the damaged stress-strain relationship for Nakanosawa sand grounds in these districts are low (21%-51%) and less than expected. Besides, it can be seen that the in-situ liquefaction strength ratio R2 o of which may denote the deformation anisotropy was Nakanosawa and Mori sands are remarkably low. The examined; the axial strain ratio ca~p/DA is the reason is that in these areas the reclaimed and the axial strain value on the compressional side at fill grounds have ·extremely low aging effects on DA=5% during the cyclic loading, as shown in the the resistance against liquefaction. Thus, .it can insert in Fig. 9. Fig. 9 shows the relationship be easily confirmed that the liquefaction strength between the axial stress ratio e. •""""P /DA and the of grounds reflects strongly the depositing manner ratio of cyclic strength ( a d/2 a' c) I (a d/2 a', ) and the depositing history. TOYQURA I Where ( (J d /2 (J 'c ) TOYDURA iS CyCliC StreSS ratio for Toyoura standard sand at Nc=20 to DA=5% and (a d/2 a',) is cyclic stress ratio evaluated at CONCLUSION the same Drc on Fig. 7. It can be seen that the ratio of cyclic strength increases noticeably with the On the basis of the limited number of cyclic decrease in axial strain ratio. On the basis of undrained triaxial tests and the estimation of anisotropy in Toyoura standard sand, it can be said in-situ liquefaction strength, the following that the effect of anisotropy on the liquefaction conclusions were obtained: strength is more significant for Nakanosawa and 1. The mechanism of increase in the liquefaction Toya sands than for Mandai· and Mori sands. strength due to the increase in relative density of Consequently, the liquefaction strength may be the damaged grounds is almost the same with that of influenced considerably by the fabric anisotropy clean fine sand such as Toyoura standard sand. induced during the depositing process of natural 2. The cyclic undrained triaxial strength of sand grounds. sandy grounds containing volcanic or fine-grained soils is smaller than that of clean fine sand. 3. The cyclic deformation characteristics are Estimation of in-situ liquefaction strength remarkably anisotropic due to fabric anisotropy formed by. the parallel alignments of particles. The The in-situ liquefaction strength of grounds feature of anisotropic behavior observed in this mentioned above may be assessed according to the study is very similar to that of naturally JRAmethod (1990), which is based on the SPT N-value deposited sandy -and volcanic grounds. and the in-situ relative density. Table 1 shows the evaluated in-situ liquefaction strength ratio R2o (i.e. cyclic stress ratio at Nc=20) with the depth ACKNOWLEDGMENT of liquefiable layer DL, the mean SPT N-value and the in-situ relative density Drm-situ . From the The authors wish to express their sincere gratitude to Messrs. M. Kajikawa, T. Arita and N. Ito who conducted major part of the experiment, and to I if 2.5 r,:;;~~::;;,:;:;:;:;;;:;:::;:;;;--;:::=;===:r:,===:1 Messrs. S. Isozaki, M. Doei, K. Kashiwagi, T. G ~ CYCLIC TRIAXIAL TEST! 0 TOYASAND Narita, T. Tsuchiya and Japan Data Service Co. for z f2 DA=5% Nc-20 I * MlzuHoRI sAND their helpful supports through this work. ~ p 2 ~ 0 NAKANOSAWA SAND f-0 e MANDAI SAND (J)N REFERENCES 0;:,:, 1 .5 ':::---.._ f:o. MORI SAND ::J'Q 00--.....--... 0 0 :. Japanese Road Association (1990), "Specifications of Highway Bridges" (in Japanese). Miura, s., Miura, M. & Saito, K. (1989), ~~ i,_..... g;~?·;~,;;~~--~-~~~~....c ..o ..m···P········*~····~-~-· .. ··············· "Earthquake-induced ground failures observed in Hokkaido, Japan", "Tsuchi-to-Kiso", JSSMFE, Vol.37, No.9: 59-64 (in Japanese). Miura, s. & Toki, s. (1984), "Anisotropy in _ _...__j mechanical properties and its simulation of ~ Q0.: Li:.:EXT:e·::::;:~=:cl=D::::A~==·:=~M:tE:__.____j _.____JL.-_.__L! sands sampled from natural deposits, Soils and 0 0.1 0.2 0.3 0.4 0.5 0.6 Foundations, Vol.24, No.3: 69-84. Miura, S., Toki, s~ & Tatsuoka, F. (1994), "Cyclic AXIAL STRAIN RATIO Ca·comp.(atDA=5%J/DA undrained triaxial behavior of sands by a cooperative tests program", ASTM STP 1213. Fig. 9 Variation of axial strain ratio due to difference in anisotropy 196