饱和砂土地震液化大位移机理研究
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摘要
饱水砂土地震液化大位移会对土工构筑物造成严重的危害,对其机理的把握是大位移预测的前提和基础。本文对饱水砂土进行了振动液化后的静扭剪及再固结试验,结果表明液化后静加载曲线可分为两段:低强度段、强度恢复段;低强度段的模量极低,在较小的剪应力作用下应变即迅速增长,强度恢复段试样的强度则逐步得到恢复。由液化后静加载应力应变曲线和再固结曲线之间的联系对大位移机理进行了分析,指出动加载阶段土体被振密使得其中孔隙水相对"富余"是静加载阶段特殊的应力应变关系及再固结体变特性的原因。
The serious damages to geotechnical structures can be caused by the large displacement induced by earthquake liquefaction.The mechanism is the basis of prediction about earthquake-induced large deformation.Here,the laboratory tests are conducted to research the behavior of saturated sand after liquefaction.Test results show that the deformation curves could be divided into two sections,e.g.,low strength segment and strength recovery segment.Then the mechanism of large deformation after liquefaction is discussed based on the test results.It is pointed out from the discussion that the "surplus water" induced by vibration is the main reason of earthquake-induced large deformation.
The serious damages to geotechnical structures can be caused by the large displacement induced by earthquake liquefaction.The mechanism is the basis of prediction about earthquake-induced large deformation.Here,the laboratory tests are conducted to research the behavior of saturated sand after liquefaction.Test results show that the deformation curves could be divided into two sections,e.g.,low strength segment and strength recovery segment.Then the mechanism of large deformation after liquefaction is discussed based on the test results.It is pointed out from the discussion that the "surplus water" induced by vibration is the main reason of earthquake-induced large deformation.
引文
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[2]Elgamal A M,Zeghal M,Parra E.Liquefaction of an artifi-cial island in kobe,Japan[J].Journal of Geotechnical Engi-neering,ASCE,1996,122(1):536-561.
[3]Holzer T L,Bennett M J,Ponti D J,et al.Liquefaction andsoil failure during 1994 Northbridge earthquake[J].Journalof Geotechnical and Environmental Engineering,ASCE,1999,125(6):438-452.
[4]Yasuda S,Nagase H,Kisu H,et al.The mechanism and asimplified procedure for the analysis of permanent grounddisplacement due to liquefaction[J].Soils and Foundations,1992,32(1):149-160.
[5]Sasaki Y,Towhata I,Tokida K,et al.Mechanism of perma-nent displacement of ground caused by seismic liquefaction[J].Soils and Foundations,1992,32(3):79-96.
[6]Pilgrim N K.Earthquake related deformation beneath gentlyinclined ground[J].Geotechnique,1998,48(2):187-199.
[7]Ishihara K,Yasuda S,Yoshida Y.Liquefaction-inducedflow failure of embankments and residual strength of siltysand[J].Soils and Foundations,1990,30(3):69-80.
[8]Ishihara K,Yoshimine M.Evaluation of settlements in sanddeposits following liquefaction during earthquakes[J].Soilsand Foundations,1992,32(1):173-188.
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