液化场地堤坝地震响应动态土工离心试验及模拟
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摘要
基于动态土工离心机试验和多重剪切机构模型的有效应力分析方法,研究了不同地震强度下,液化场地堤坝的地震响应和大变形特征。动态土工离心机试验的液化场地模型,由相对密度为30%的饱和砂土构成,输入正弦波峰值分别为0.8056、1.7903和3.133m/s2。并采用有效应力分析有限元程序对堤坝的动点响应进行数值模拟,计算结果与模型试验结果相吻合。在此基础上研究了堤坝的加速度、变形以及下卧液化场地中的超孔隙水压力分布规律,分析了液化场地不同位置土层中的有效应力路径变化规律。研究得出,液化场地堤坝顶和坝趾在地震作用下会发生较大的沉降和侧向扩展,且随地震强度加大而增大。堤坝下卧浅层液化土的超孔隙应力比相对较小但其体积变形较大,坝顶的残余沉降可达1.4m,地震中堤坝底部土体同自由场地土体的有效应力路径和应力-应变特征不同。土工离心机试验结果同数值解析结果基本吻合。
The seismic behaviors of dykes with saturated liquefiable soil foundation are studied by dynamic centrifuge model test and numerical simulation.The peak shaking amplitudes of sine wave input motion in model test are 0.8056m/s~2,1.7903m/s~2 and 3.133m/s~2 respectively,and the relative density of the foundation soil is 30%.At the same time,the effective stress analysis method is applied to carry out the numerical simulation of the seismic response of a dyke.It is found that the calculated settlement of the dyke,acceleration and excess pore pressure of sand deposit are in good agreement with the results of model test.Both physical model and numerical model indicate that the dykes built on liquefiable soil foundation subjected to earthquake motion may result in lager settlement and lateral spread.The stronger the motion,the larger deformation of dyke is.The ratios of excess pore water pressure are small in the liquefiable soil beneath the dyke in spite of large deformation.The characteristics of effective stress path and stress-strain relationship of the liquefiable soil beneath the dyke are different from those in free field.
The seismic behaviors of dykes with saturated liquefiable soil foundation are studied by dynamic centrifuge model test and numerical simulation.The peak shaking amplitudes of sine wave input motion in model test are 0.8056m/s~2,1.7903m/s~2 and 3.133m/s~2 respectively,and the relative density of the foundation soil is 30%.At the same time,the effective stress analysis method is applied to carry out the numerical simulation of the seismic response of a dyke.It is found that the calculated settlement of the dyke,acceleration and excess pore pressure of sand deposit are in good agreement with the results of model test.Both physical model and numerical model indicate that the dykes built on liquefiable soil foundation subjected to earthquake motion may result in lager settlement and lateral spread.The stronger the motion,the larger deformation of dyke is.The ratios of excess pore water pressure are small in the liquefiable soil beneath the dyke in spite of large deformation.The characteristics of effective stress path and stress-strain relationship of the liquefiable soil beneath the dyke are different from those in free field.
引文
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[16]Iai S,Matsunaga Y,Kameoka T.Parameter identification for a cyclic mobility model[J].Rep Port Harbour Res Inst,1990,29(4):57-83.
[2]汪明武,金菊良,李丽.基于实码加速遗传算法的投影寻踪方法在砂土液化势可视化评价中的应用[J].岩石力学与工程学报,2004,23(4):631-634.
[3]Sharma J S,Bolton M D.Finite element analysis of centrifuge tests on reinforced embankments on soft clay[J].Computers and Geotechnics,1996,19(1):1-22.
[4]Osutsumi O,Sawada S,Iai S,et al.Effective stress analysis of liquefaction-induced deformation in river dikes[J].SoilDynamics and Earthquake Engineering,2002,22(10):1075-1082.
[5]徐志英,沈珠江.高尾矿坝地震液化与稳定分析[J].岩土工程学报,1981,3(4):22-32.
[6]周健,董鹏,戚佩江.灰渣坝抗震稳定性的三维有效应力动力分析[J].水利学报,2000,(7):44-48.
[7]李万红.土石坝地震变形和滑波及液化非线性分析[J].水利学报,1996,(8):65-70.
[8]赵剑明,汪闻韶,张崇文.土石坝振动孔压影响因素的研究[J].水利学报,2000,(5):54-59.
[9]王媛,姜朴,朱俊高,等.松粉砂地基地震后堤坝稳定性分析[J].水利学报,2000,(11):60-69.
[10]邵生俊,小启介,福井卓雄.砂土堤基的动力反应计算与模型试验[J].水利学报,2002,(4):28-32.
[11]李湛,栾茂田.竖向地震加速度对堤坝抗震性能影响分析[J].大连理工大学学报,2006,46(4):538-542.
[12]蔡袁强,钱磊,凌道盛,等.钱塘江防洪堤地震液化及稳定分析[J].水利学报,2001,(1):57-61.
[13]徐长节,蔡袁强.杭州钱塘江防洪堤抗震分析[J].岩土力学,2006,(01):67-72.
[14]Iai S,Matsunaga Y,Kameoka T.Strain space plasticity model for cyclic mobility[J].Soils Foundations,1992,32(2):1-15.
[15]Wang Mingwu,Iai S,Tobita T.Effective stress analysis of underground RC structures during earthquakes[J].Annuals ofDisaster Prevention Research Institute,Kyoto University,2005,47(B):371-382.
[16]Iai S,Matsunaga Y,Kameoka T.Parameter identification for a cyclic mobility model[J].Rep Port Harbour Res Inst,1990,29(4):57-83.
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