饱和松砂与结构接触面反复剪切下邻近土体性状数值分析

该文采用颗粒离散元软件PFC2D，研究了不排水条件高频循环剪切作用下饱和松砂与板桩接触面附近的砂土特性，分析了模型参数对饱和松砂孔隙率和体应变的影响，以及剪切过程中超静孔压的变化规律和砂土颗粒的运动轨迹。结果表明：当颗粒摩擦系数、颗粒刚度、剪切振幅和剪切频率越小或边界围压和接触面摩擦系数越大，饱和松砂的剪缩现象越明显。砂土的孔隙率在作用瞬间减少、然后略有增加后呈下降趋势至稳定；随循环次数增加，砂土中的超静孔压总体上呈增长趋势；砂土颗粒的变位随离开接触面距离的增加而减小。

NUMERICAL ANALYSIS OF THE BEHAVIOR OF SATURATED LOOSE SAND ADJACENT TO STRUCTURES

The behaviors of the sands near the interface between saturated loose sand and a sheet pile in an undrained state under high frequency cyclic shear are simulated by using the particle flow code in 2-dimension (PFC2D).The parameters which influence the volume strain and porosity of loose saturated sand near the interface are investigated.Besides,the variation of pore water pressure and the particle motion traces near the interface are studied.Numerical simulation results show that shear-contraction appears in saturated loose sand during high frequency cyclic shear,and the shear-contraction is obvious when the values of the parameters,including the particle friction coefficient,particle stiffness,shear amplitude and shear frequency,are smaller.However,it is also obvious when the values of the parameters,including boundary confining pressure and frictional coefficient,are larger.The porosity of the sand near the interface decreases firstly,then increases a little,and then decreases until reaching a steady value.The pore water pressure near the interface increases cumulatively.Sand particles near the interface have large displacements,and the value of the displacement become larger and larger with the reduction of the distance between the interface and sand particles.