To explore the variation process of seepage field of a three dimensions slope due to rainfall infiltration

routines for improvement of the capability of unsaturated seepage calculation of FLAC3D software were programmed by using FISH language after the analysis of unsaturated seepage module and seepage calculation algorithm used in FLAC3D platform. Based on the analysis of infiltration mechanism of rainfall

some FISH routines for simulation of rainfall infiltration and oozing of pore water in the slope after raining stop were programmed. The variation process of saturated and unsaturated seepage field of an engineering slope under the rainfall condition was simulated by employing FLAC3D software and the developed routines. The variation law of transient saturated area in the slope due to rainfall infiltration was explored and compared to the results in references cited in the paper. The distribution of transient saturated area in the slope obtained by calculation is same as the results presented in the cited references. It shows that the simulation of rainfall infiltration and unsaturated seepage analysis could be fulfilled corrected by employing FLAC3D platform with the relevant routines developed by users. The proposed method for the calculation of unsaturated seepage process provides a significance way for the simulation of seepage field of three-dimensional slope.