中文摘要：

基于饱和土体Biot固结理论,考虑土体体力与表面作用力,结合饱和土体中土骨架动力平衡方程与孔隙流体的连续方程,在计算域内采用Galerkin加权余量法,推导了3D无限、有限域全耦合饱和土体固结的比例边界有限元方程.理论推导表明：与单相弹性土体不同的是,由于孔隙水的存在,饱和土体固结比例边界有限元法方程中不仅有位移、应力矩阵,而且还存在孔隙水压力的影响耦合矩阵;该方程不仅能够满足无限域无穷远边界辐射条件,而且在径向（与饱和土体-结构接触面垂直方向,指向无限远）上具有严格的精确性,环向上（与饱和土体-结构接触面平行方向）具有有限元单元无限收敛的准确性.

英文摘要：

Based on the Biot＇s dynamic coupled consolidation theory,the scaled boundary finite-element method was developed to correctly model the dynamic unbounded far-field boundary of three-dimensional（3D）fully saturated soil in this paper.Body forces and surface tractions were considered in the derivation.The concept of similarity,the compatibility equation,Biot＇s coupled consolidation equations,and the Galerkin＇s weighted-residual method were used to derive the formulation for the governing equations.The main difference from the single-phase version was the presence of pore water pressures as additional parameters to be solved,in addition to the displacements,strain and stress which were incorporated into the static-stiffness matrices by producing fully coupled matrices.Solving the resulting equations yielded a boundary condition satisfying the far-field radiation condition exactly.The computed solutions were exact in a radial direction（perpendicular to the boundary and pointing towards infinity）,while converging to the exact solution in the finite element sense in the circumferential direction parallel to the soil-structureboundary interface.