液化场地桩-土相互作用大变形无网格法分析
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摘要
将无网格法应用于地震液化过程中的桩-土相互作用分析.以Biot固结理论的u-p列式作为饱和砂土的控制方程,土的本构关系采用能够描述饱和土体振动液化特征的有效循环弹塑性模型.利用移动最小二乘近似推求形函数,再采用伽辽金法对控制方程离散,获得无网格伽辽金法的基本计算方程.最后,通过优势验证,说明了该方法能有效地避免液化有限元分析时由于大变形所引起的体积自锁而使计算中断等问题.
The meshless method is applied to seismic analysis of soil-pile interaction in liquefiable site. The governing equations are established by u-p formulation of Biot's two-phase mixture theory,and a cyclic elasto-plastic model describing the vibrating liquefaction characteristics of saturated soil is adopted to deal with the constitutive relation of the soil. The shape function is deduced by the moving least square method,then the Galerkin method is used to discretize the governing equations,and the basis function equations of the element-free Galerkin method are built. Finally,the effectiveness of the method is demonstrated by comparing the results with those of finite element method. The meshless method can effectively avoid the volumetric locking due to large deformation which usually occurs in the numerical computations using finite element method.
The meshless method is applied to seismic analysis of soil-pile interaction in liquefiable site. The governing equations are established by u-p formulation of Biot's two-phase mixture theory,and a cyclic elasto-plastic model describing the vibrating liquefaction characteristics of saturated soil is adopted to deal with the constitutive relation of the soil. The shape function is deduced by the moving least square method,then the Galerkin method is used to discretize the governing equations,and the basis function equations of the element-free Galerkin method are built. Finally,the effectiveness of the method is demonstrated by comparing the results with those of finite element method. The meshless method can effectively avoid the volumetric locking due to large deformation which usually occurs in the numerical computations using finite element method.
引文
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[11]凌贤长,唐亮,于恩庆.可液化场地地震振动孔隙水压力增长研究的大型振动台试验及其数值模拟[J].岩石力学与工程学报,2006,25(增2):3998-4003
[2]YANG Z,JEREMIC B.Numerical analysis of pile behaviour under lateral loads in layered elastic-plastic soils[J].International Journal for Numerical and Analytical Methods in Geomechanics,2002,26(14):1385-1406
[3]LU C W,OKA F,ZHANG F.Analysis of soil-pile-structure interactionin a two-layer ground during earthquakes considering liquefaction[J].International Journal for Numerical and Analytical Methods in Geomechanics,2008,32(8):863-895
[4]WILSON D W.Soil-pile-structure interaction in liquefying sand and soft clay[D].California:Depart ment of Civil Engineering,University of California at Davis,U.S.A,1998
[5]SATO T,MATSUMARU T.Liquefaction and ground flow analysis using the element free Galerkinmethod[C]//Proceedings of KKCNN Symposium on Civil Engineering.Gyeongju:Gyeongju University,2003
[6]TANG X,SATO T.Effects of multi-directional input motion to response of pile in liquefiable soils[C]//Proceedings of the37th National Conference of Japanese Geotechnical Society(CD-ROM).Kyoto:The University of Kyoto,2002
[7]OKA F,YASHI MA A,TATEISHI A,et al.A cyclic elasto-plastic constitutive model for sand considering a plastic-strain dependence of the shear modulus[J].Geotechnique,1999,49(5):661-680
[8]CHEN WF,MIZUNO E.Nonlinear Analysis in SoilMechanics[M].New York:Elsevier Science,1990
[9]LANCASTER P,SALKAUSKAS K.Surfaces generated by moving least squares methods[J].Mathematics and Computation,1981,37(155):141-158
[10]CORDES L W,MORAN B.Treat ment of material discontinuity in the element-free Galerkin method[J].Computer Methods in Applied Mechanics and Engineering,1996,139(1-4):75-89
[11]凌贤长,唐亮,于恩庆.可液化场地地震振动孔隙水压力增长研究的大型振动台试验及其数值模拟[J].岩石力学与工程学报,2006,25(增2):3998-4003
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