地層が傾斜した沿岸地盤の側方流動に関する液状化解析

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1 京都大学防災研究所年報第 50 号 B 平成 19 年 4 月 Annuals of Disas. Prev. Res. Inst., Kyoto Univ., No. 50 B, 2007 ጀ߇ ᢳߒߚᴪጯ ߩ ᣇᵹ ߦ㑐ߔࠆᶧ ൻ ᨆ * ጟ ᓟ㓁 * *੩ㇺᄢቇᄢቇ㒮Ꮏቇ ⑼ ⷐ ᣦ 㔡 ߩᶧ ൻߦࠃࠆ ᣇᵹ ߪ㧘 ᢳߒߚ ߦᶧ ൻጀࠍ ߔࠆ႐วߣ ጯߩ 㕙 ߦᶧ ൻጀࠍ ߔࠆ႐วߦࠊߌࠄࠇࠆ ޕ ᚭߩᴪጯㇱߦ߅ ߡߪጊ߆ࠄᶏߦ߆ߌߡ ጀ߇ ᢳߒߡ߅ࠅ㧘ߘߩ ߦ ጯ ㅧ ߇ሽ ߔࠆ ᚲ߇ ࠄࠇࠆ ᧄߢߎߘޕ ߢߪ㧘 ᖱႎ ࡌ ࠍ ߡ ᚭߩ ࠍࡕ ൻߒ㧘 ߩ➅ ߒᒢ ᕈ ᚑᑼࠍ ߚ 㒢ⷐ ᨆᴺߦࠃࠆ ጯ ㅧ ࠍኻ ߣߒߚ ᐶ ධㇱ㔡 ߩᶧ ൻ ᨆࠍⴕ ߞߚ ᨐࠍ ߔ ߚ ޕ 㧘 ᨆ ᨐߣ 㔡ᓟߩ ᣇᵹ ታ ࠍ セߒ㧘 ᨆࡕ ߩ ᬌ ࠍⴕ߁ߣ ߦ㧘 ᣇᵹ ߩ ߦߟ ߡᬌ ߒߡ ࠆ ޕ ᶧ ൻ㧘 ᣇᵹ 㧘 ߩ ᢳ㧘 ጯ ㅧ ߪߓ ߦ ࡌ ޟ ᚭJIBANKUN ޠ 㧔 ᚭߩ ળ㧘 1999㧕ࠍ ߚ ߚ ޕ 㧘ᶧ ൻ ᨆߦߪ ߩ➅ ߒ ᐶ ධㇱ㔡 ߦߪ㧘ᶧ ൻ߇ ߒ Ꮏፉ ᒢ ᕈ ᚑᑼߦࠃࠆᶧ ൻ ᨆᴺ㧔ᶧ ൻ ᨆᚻᴺ ᴪጯㇱߩ ጯ ㅧ ߦ߅ ߡ㧘 ᣇᵹ ߦࠃࠆⵍኂ LIQCA㐿 ࡊ㧘2004㧕ࠍ ߚ ޕ ᨆߢᓧࠄ ߇ ᄢߢ ߞߚ ޕ Fig. 1ߦ ᚭߩઍ ߥ ᢿ㕙 ࠇߚ ጯ ㅧ ߩ ᣇᵹ ㊂ߣ ᐶ ධㇱ㔡ᓟߦ ࠍ ߔ ޕ ᚭᴪጯㇱߩ ߪ㧘 Ꮊ ᚸ ߦ ᒰ ߐࠇߚ ᣇᵹ ㊂ࠍ セߒ ᨆࡕ ߩᬌ ࠍ ߒ㧘ᴒ ߩၸ ጀߪਥߦ ߆ࠄ ᚑߐࠇߡ߅ࠅ㧘 ⴕ߁ߣ ߦ㧘 ᣇᵹ ߩ ߦߟ ߡᬌ ߒߚ ޕ ጀߪ㒽߆ࠄᶏߦ߆ߌߡ ߆ߦ ᢳߒߡ ࠆ㧔 ߃ 㧘 ᚭߩ ળ㧘2002㧧㑐 ᖱႎᵴ ද ળ㧘1998㧕 ߚ ޕ 㧘 ᚭߦߪ Ꮏፉ ၒ ߇ ᭗ᵆᶋᵇ ᄙߊሽ ߒ㧘 ጯ ㅧ ߪᄙᢙሽ ߔࠆ ޕ 㒽ߩᴪ ᵓᵎ Ac䋨ᴒ ᕈ 䋩 Ma13䋨ᴒ ᶏᚑ ᕈ 䋩 As䋨ᴒ 䋩 Ma12䋨ᵩ ᶏᚑ ᕈ 䋩 Ag䋨ᴒ 䋩 F䋨ၒ 䊶䋩 Dc䋨 ਐ ᕈ 䋩 Gr䋨ၮ ጤ䋩 Ds䋨 ਐ 䋩 Land Ds䋨 ਐ 䋩 ጯㇱ ၒ ߢߪᔅὼ ߦ ਅ ߪ㜞 ߚ 㧘 ᚭߩ ߪᶧ ൻߒ ߔ ߣ ߃ࠄࠇࠆ ޕ Sea ᵎ ᣇ㧘㔡 ߩᶧ ൻߦࠃࠆ ᣇᵹ ߪ㧘 ᢳߒ ߚ ߦᶧ ൻጀࠍ ߔࠆ႐วߣ ጯߩ 㕙ߦᶧ ᵋᵓᵎ ൻጀࠍ ߔࠆ႐วߦࠊߌࠄࠇࠆ ޕ ᚭߩᴪጯㇱߦ߅ Ag As ߡߪጊ߆ࠄᶏߦ߆ߌߡ ᢳߒߚ ߦ ጯ ㅧ B (reclamation) ᵋᵏᵎᵎ ߇ሽ ߔࠆ ᚲ߇ ࠄࠇࠆ ߩߎޕ ߆ࠄ㧘ᶧ ൻ ߇ ߒߚ႐วߦ㧘 ጯ ㅧ ߇ ᣇᵹ ࠍ ߎߒ Fig. 1 Representative geologic profile of the central Kobe ߔ ઙߢ ࠆߣ ߃ࠄࠇࠆ ޕ ίresearch committee for ground of Kobeύ1998ὸ ߘߎߢᧄ ߢߪ㧘 ጀ߇ ᢳߒߚ ߦ ጯ ㅧ ߇ሽ ߔࠆࡕ ࠍ ቯߒ㧘 ᐶ ධㇱ㔡 ᶧ ൻ ᨆᴺ ߩ 㔡ᵄࠍ ജᵄߣߒߚᶧ ൻ ᨆࠍⴕ߁ ߦࠃࠅ㧘 ߩᶧ ൻ ߣ ጯ ㅧ ߩ ᣇᵹ ߦߟ ߡ Oka et al.㧔1999㧕ߪ㕖 ᒻ⒖ ൻ ߦၮߠߊ➅ ᬌ ࠍⴕߞߚ ޕ ߩࡕ ൻߦߪ㧘 ᖱႎ ߒᒢ ᕈ ᚑᑼࠍ㐿 ߒߚ ᧄޕ ߩ ᨆᴺߪ㧘 387

2 ߎߩ ᚑᑼࠍ ߚ㧘㧙 ㅪᚑ 㒢ⷐ ᨆ ಽᏓߥߤߩ ߣᣢᓔߩᶧ ൻ ᨆ߆ࠄᢙ୯ࠍផ ᴺLIQCA2D04㧔ᶧ ൻ ᨆᚻᴺLIQCA㐿 ࡊ㧘 ቯߒ㧘 ᨆߢᓧࠄࠇߚ ጯߩ ᐔ⒖ ㊂߇ 㔡ᓟߦ 2004㧕ߢ ࠆ ޕ ߐࠇߚታ㓙ߩ⒖ ㊂ߣ ᢛวࠍᓧࠆࠃ߁ߥࡄ ࡔ ࠍ ⴕ ߦࠃࠅ ቯߒߚ ࡔ ࡄߩߎޕ ᨆኻ ᢿ㕙ߩࡕ ൻ ࠍ ߡ ߩ➅ ߒᒢ ᕈ ᚑᑼߢ㕖ឃ ➅ ߒ ゲ㛎ࠍ ࡒࡘ ߒߚ ޕ ၒ ጀߣAs1ጀߩ Fig. 2 ߦ ࡕ ൻߒߚ ߩ ᢿ ࠍ ߔ ޕ ᔕജ㧙 ߕߺ㑐ଥ㧘 ലᔕജᓘ ࠍFig. 5ߦ㧘ၒ ጀ ߎࠇߪ㧘 ᖱႎ ࡌ ޟ ᚭJIBANKUN ޠ ߣAs1ጀߩᶧ ൻᒝᐲᦛ ࠍFig. 6ߦ ߔ ޕ Fig. 6ߦߪ ߩࡏ ߆ࠄផቯߒߚ ᚭᴪጯ ߩ ᚭ ߦ߅ߌࠆᣢᓔߩታ㛎 ᨐࠍวࠊߖߡ ߒߡ ߢ ࠅ㧘 ᕈ ߩ ጀ߇㒽 ߆ࠄᶏ ࠆ߇㧘 ᨆߢᗐቯߒߚ ߪ㧘 ᚭ ߦ߅ߌࠆ ߆ߌߡ ᢳߒߡ ࠆ ሶ߇ ߃ࠆ ߩߎޕ ᢿ㕙ߦߪ ߩታ㛎 ᨐߦᕈ ߇㘃 ߒߡ ࠆߣ ߃ࠆ ޕ ㆇᴡߩ ጯߣ㒐ầ ࠍࡕ ൻߒߡ߅ࠅ㧘 ጯ ߥ߅㧘ᶧ ൻኻ ጀએᄖߩ ጀ߅ࠃ ጀߪ㧘 ߪ ᢳߒߚ ጀߩ ߦሽ ߒߡ ࠆ ޕ Fig. 1 ߦ ߔ ߩ1ᧄߩࡏ ߦߟ ߡ㧘ᶧ ൻ ቯ ᶧ ൻߩ ࠍ ᘦߒߥ ߆ࠄ㧘 ଥᢙ D0 0 ߣߒ㧘ၮḰ ߕߺߦࠃࠆ ᕈૐਅߪή ࠍⴕߞߚ ᨐ㧔 ᐶ ධㇱ㔡 ᵄࠍ ߚ㧕㧘 ߩࠍߒߚ ߚ ޕ 㧘 ᕈ ጀߪR-Oࡕ 㧘 ጯ㨯 ᴒ ጀ߇ᶧ ൻኻ ጀߣߥߞߚ߇㧘 ጀߩᶧ ൻ 㒐ầ ߪᒢᕈ ࠍ ቯߒߚ ޕ 1 ࡊᒰߚࠅߩ 㑆 ᛶ ߇ᄢ߈ߊPL୯ߪ5.6ߢ ߞߚ ޕ ჇಽӠ t㧩0.001 (sec)ߣߒ㧘 ࡊᢙߪ30000 (step)ߢ ࠆ ޕ ᨆ ઙߣ ജ 㔡ᵄ 㪏㪇㪇㪘㪺㪺㪼㫉㪼㫃㪸㫋㫀㫆㫅㩷㩿㪾㪸㫃㪀㪍㪇㪇 ᨆߦ ߚࡔ ࡘ ߣႺ ઙࠍFig. 3 ߦ ߔ ޕ ਅ ߪᵩ ߩ ጀ㧔Dg2ጀ㧘GL-50m㧕 ߢࠍ ࡕ ൻߒ㧘㔡ᵄࠍ ജߒߚ ޕ ജᵄߪ㧘 ᐶ ධㇱ㔡ࠍᗐቯߒ㧘KBPR㧔ฎᧄࠄ㧘1999㧕߅ࠃ FDEL 㪋㪇㪇㪉㪇㪇㪇㪄㪉㪇㪇㪄㪋㪇㪇㪄㪍㪇㪇㧔᧖ᚭࠄ㧘1994㧕ࠍ ߡ ߐࠇߚ 㔡ᵄߢ ࠆ 㪄㪏㪇㪇㧔Fig. 4㧕 ޕ 㪇㪌㪈㪇㪈㪌 ߚ㧘Table 1 ߦ ᨆߦ ߚᶧ ൻኻ ጀߩࡄ 㪉㪇㪉㪌㪊㪇㪫㫀㫄㪼㩷㩿㫊㪀 ࡔ ߔ ᧄޕ ߢߪ㧘ࡄ ࡔ ࠍ ቯߔࠆߩ Fig. 4 Seismic input motion (Calculated wave of the ߦᔅⷐߥ ᩏ 㛎ࠍⴕߞߡ ߥ ߚ 㧘N୯ ᐲ 1995 Hyogoken-Nambu earthquake, NS component).cpf +PNCPFTGXGVOGPV $TGCMYCVGT 5GC 8GTVKENCEQQTFKPCVG #NNWXKCN $CEMHKNN 2.㧦 )TCXGN 5KNV 2NGKUVEGPG 4GRNCEGFUQKN %NC[ 5CPF Fig. 2 Ground profile deduced by the ground information database ᵓᵏᵏᵌᵒᾼ #I #I #E #E ᵖᵓᵌᵎᾼ 4GF 'NCVQ RNCEVKE/QFGN (QWPFCVKQP #UE #U #U ᵐᵔᵎᵌᵎᾼ ᵐᵗᵎᵌᵎᾼ 9CXG FKUUKRCVKPIDNQEM 4GXGVOGPV (QWPFCVKQP #U $ $TGCMYCVGT 4GRNCEGFUQKN ၮ 9CVGT.GXGN &TCKPGF #U /C ᵓᵎᵌᵎᾼ 7PFTCKPGF *QTK\QPVCNN[HKZGF 7PFTCKPGF (KZGF &I &I &E 8GTVKECNEQQTFKPCVG Fig. 3 Finite element meshes and boundary conditions 388 7PFTCKPGF *QTK\QPVCNN[HKZGF

3 Table 1(a) Material parameters for cyclic elasto-plastic model Material B Ba As1 As2 As3 Density (g/cm 3 ) Coefficient of permeability k (m/s) Initial voild ratio e Compression index Swelling index Quasi-overconsolidation ratio OCR * Initial shear modulus ratio G0 / ' m Phase transformation stress ratio M * m Failure stress ratio M * f Hardening function parameter B * Hardening function parameter B * Hardening function parameter C f P* r E* r Dilatancy coefficient parameter D Dilatancy coefficient parameter n Table 1(b) Material parameters of cyclic elasto-plastic model for non-liquefiable ground Material As4 Ag1 Ag2 Dg1 Dc1 Dg2 W.-D. block Density (g/cm 3 ) Coefficient of permeability k (m/s) Initial voild ratio e Compression index Swelling index Quasi-overconsolidation ratio OCR * Initial shear modulus ratio G0 / ' m Phase transformation stress ratio M * m Failure stress ratio M * f Hardening function parameter B* Hardening function parameter B* 1 Hardening function parameter C f P* r E* r Dilatancy coefficient parameter D Dilatancy coefficient parameter n Table 1(c) Material parameters for R-O model and elastic model Material Ma13 Ac1 Ac2 Asc1 Foundation Revetment Density (g/cm 3 ) Coefficient of permeability k (m/s) Initial void ratio Lame s constant (kpa) 2.70E E+06 Lame s constant (kpa) 1.80E E+06 Poisson's ratio Cohesion c (kpa) Internal friction angle (deg) Parameters of shear modulus a Parameters of shear modulus b Parameters of R-O nonlinearity Parameters of R-O nonlinearity r

4 Stress-strain relation Effective stress path (a) Backfill soil Stress-strain relation Effective stress path (b) Alluvial sand Fig. 5 Stress-strain relations and effective stress path obtained by numerical simulation of undrained cyclic triaxial test, (a) Backfill soil (b) Alluvial sand Fig. 6 Experimental liquefaction strength curves for soils of Kobe and numerical simulation of liquefaction strength curves for backfill soil, B layer, and Alluvial sand, As1, layer (Higashi and Tamura 1997 Geo-Database Information committee of Kansai1998 Tanaka1998) Fig. 7 A B Fig. 8B Fig. 9 1 ' m / ' m0 ' m ' m

Lateral (Observed lateral displacement 0.63m displacement = Lateral flow towards canal 1.09m canal = Lateral flow towards canal (Observed 0.85m lateral displacement : 0.85m) 0.

5 Lateral (Observed lateral displacement 0.63m displacement = Lateral flow towards canal 1.09m canal = Lateral flow towards canal (Observed 0.85m lateral displacement : 0.85m) 0.11m Lateral displacement Lateral flow towards canal 0.78m canal Lateral flow towards canal Lateral flow towards sea Revetment A Lateral flow towards sea Revetment B Fig. 7 Deformed mesh of inland revetments (Black: Initial state t 0 (s), Red: t 30 (s)) Lateral flow towards sea Settlement behind the revetment 0.14m Sea Lateral flow towards sea Breakwater Lateral displacement: 0.14m Fig. 8 Deformed mesh of breakwater (Black: Initial state t 0 (s), Red: t 30 (s)) Fig. 9 Distribution of mean effective stress decreasing ratio B LIQCA 2004 LIQCA2D JIBANKUN No.493/II-27 pp Vol.47No.6pp Vol.39No.9pp

6 CD-ROM Oka, F., Yashima, A., Tateishi, A., Taguchi, Y. and Yamashita, S. (1999) A cyclic elasto-plastic constitutive model for sand considering a plastic strain dependency of the shear modulus, Geotechnique, Vol.49, No.5, pp A Liquefaction Analysis for Lateral Flows of Slightly-inclined Coastal Ground Fusao OKA* and Yosuke HIGO* * Graduate School of Engineering, Kyoto University Synopsis It is well known that lateral flows due to liquefaction are often observed in saturated sand layer existing in slightly inclined ground or ground behind revetments. One of the features of geological structure of Kobe is inclination from land to sea, and for the other there are many revetments and reclaimed land in coastal area. The present paper describes a liquefaction analysis for lateral flows of slightly-inclined coastal ground using a cyclic elasto-plastic constitutive model and dynamic finite element method. The input wave is the Hyogoken-Nambu earthquake. Comparing displacement of revetments obtained by numerical simulation and that by the observed data, validation of the analysis model and lateral flow behavior of revetments are discussed. Keywords: liquefaction, lateral flow, slightly-inclined ground, revetments

Microsoft Word - 地震工学論文v5.doc

Microsoft Word - 地震工学論文v5.doc 1 1 400-8511 4-3-11 E-mail:takeyasu@yamanashi.ac.jp AHP Key Words : disaster management system, usability, improvement, evaluation test, disaster response analytic hierarchy process 1) 2) 3) 4) 5) AHP