Liquefaction Damage of Sandy and Volcanic Grounds in the 1993 Hokkaido Nansei-Oki Earthquake
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Missouri University of Science and Technology Scholars' Mine 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 Follow this and additional works at: https://scholarsmine.mst.edu/icrageesd Part of the Geotechnical Engineering Commons Recommended Citation Miura, S.; Yagi, K.; and Kawamura, S., "Liquefaction Damage of Sandy and Volcanic Grounds in the 1993 Hokkaido Nansei-Oki Earthquake" (1995). 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(\ 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<e GRAIN SIZE (lnm) Fi9. 3 Borinq logo o! each eaoupling dtee Note : 'The curve:; Willrl ottqut .,M lnclcow ~o rengt of ~n ai:te ols01bullons lor oil .....,.,... lak., tom 10 - .. again. Kakanooawa oandJ Ttlis sand was t.aken frca eoill Fiq. 5 Grain si'e distr ibution curves boiled at the play9rOW1d of Ral<anosawa EJ.ementary School (toeal area = 3,500 m'), located in the coanal plane ot volcanic say. 1\S sh""-n in tbe volcanic soils ""''ere ..liquefied and ejected ont.o tb~ ilulllrt in Fig .1, eantl boils with not leu tban 30 9round surface. It ic vorthy of note that cratl>rt including iron sand were Ol>oervod. This liquetaetioo- induced volcanic soil ground area bad been excavated tor collect1n9 iron a a n~ .t&ilu.reG"'-ere observed. during 1951-1965. In most ot tbis oreo, liquefaction was responsible for the dlllMqes. Mandai sand: In Bakodate city, oart.bquake TBST PROCllDURE induced<aamages were l imited almost to reolaimed lands along the Port of Bakodate. Mandai sand was In t bis study, f i ve kinde ot sandy soils described s ampled froiG boiled s ands at Mandai quay coneiatin9 above were used t oe cyclic undrained triaxial mainly o! drod9cd soils. As can be seen in Fig.3, teote. All t he triaxial opeciouens l.l$re prepared sn N- valu of this qround is e ..tr<~onely low, According to the air pluviotion mothod (AP-method, irroopoctive ot high fine contont Fc(• 49\, whicoh 1• Miura et al. ( 1994)). Di.otension ot epecimen h 10m.-. conti..med in the grain oize distribution curveo in diameter by 170mm in heiqht: Relative densi ties (l'ig.$)). Therefore, it ! e considered that after the desir<!d isotropic conoolidati.On Drc were liquefaction occurred also in the sandy gJ:"oundo a~d to be 75t, 55\ , and 90\ . Probably, due to containin9 fine-grained soils. adopting the air pluviation method, only relative 110ri pand 1 Moet of t he Kori Port area baa be.e.n deneity of 105' was attained for Mandai sand. For reclaiJDed by filling·the s and containing volca.nic Hori sand, ore of 86t and 100\ were obtained. After soUs as indicated in the boring log in Fig.). Due each specimen i s cet up in tM c•ll, and then 'the to l J.gUetaction1 of saudy and. volcanic aoUe, cell precao.re- ia raised to 19. 6kPa, carbon di oxide collapse of quay walla aod oeri ou.a set'tloent• of is percolated tbrough the apOCimen tor about JO aprons were observed (l'i<J.4) . The volcanic soils llinu~e& . Subaequently, de-aired -wat&r ie permeated coDSist 1114inly o! tall deposits of Mt.Koma9atake't into t..~e voids at a soull d ifterenti&l head eruption. In the Akaigawa district near the Mori (4 .9kPa) $ 0 as to free frOlll the disturbance of Port, locatad in t.he foot. ot Ht .Kom.agataka, initial fabri c s . Bac k preeeure ot 196kPa is , thereafter, applied for around one hour to ensure sieving pluviation method (MSP-method, Miura & the saturation of the specimen. By this procedure, Toki ( 1984) ) • It is noted in Fig. 7 that the Bishop's B value is equal to or larger than 0.96. variation in the liquefaction strength due to the After consolidating isotropically for one hour at difference of specimen density is almost similar to an effective confining stress a', of 49kPa, a that of clean fine sand such as Toyoura standard series of cyclic triaxial tests is performed under sand, except in the range of high relative density. the undrained condition with the loading frequency It can be also pointed out that the liquefaction of0.1Hz (Miuraetal.