MULTIREGION BOUNDARY-ELEMENT ANALYSIS OF UNCONFINED SEEPAGE PROBLEMS IN EXCAVATIONS

A multi-region boundary element method (BEM) is presented for the seep age analysis in deep excavations. In the formulation, soil foundation is regarded as a multilayered porous medium possessing the zoned inhom ogeneous hydraulic conductivity. Based on Darcy's law, a two-dimension al steady state differential equation with transient free surface cond itions is adopted. With a fundamental solution of the potential proble m, a generalized multi-region boundary element method is developed. Th e transient boundary conditions are treated by means of the Galerkin s cheme of the theta family approximation and are imposed into the bound ary integral formulation. The essential features of the BEM are that i t concerns the zoned inhomogeneous hydraulic conductivity of soil medi a, and that the assembly of each individual region can process in the same way as in finite element method (FEM) with much less computer mem ory storage. Several unconfined seepage problems are solved to demonst rate the performance of the multi-region BEM. Copyright (C) 1996 Elsev ier Science Ltd.