Abstract: An improved FEM for the seepage field calculation of tailings dam is proposed based on the traditional moving grid method.Its difference from the moving grid method lies in that, in specific calculation, the whole dam is considered as a seepage field, which requires only the assumption of the elevation of egress points instead of that of free liquid surface.The gridding may be made on the whole dam body, with only the refining for the area near the egress points required.In the interactive progress, only a local correction for the grids near the egress points is required, without considering the grid adjustment in the seepage zone.The link line of the points whose pore water pressure equals zero in the field that is got after the calculation is the seepage line.The correctness of the method is further verified by practical engineering cases.

Key words: Tailings dam, Seepage field, FEM, Free liquid surface