Abstract:Solution of seepage analysis with a free surface by Trefftz direct method is presented. Compared with traditional boundary element method and finite element method,Trefftz direct method avoids the difficulty of singular integral and the inconvenience of mesh modifications. Steady seepage and unsteady seepage with a free surface in a homogeneous earth dam were analyzed. Compared with a glycerin experimental result,the elevation of release point and its relative error are listed in a table. The numerical results show that the proposed method has its advantages. It takes less computation time and has satisfactory accuracy and convergence.