Abstract:By means of 3D FEM non-linear analysis of an arch dam having a dam toe with developed geological structure, the influence is discussed of temperature,seepage,terrain and geological flaws in the foundation on the arch dam and mechanical behaviors of foundation when the dam is working. The distribution of the displacement field,and the stress field of the arch dam with complex foundation and characteristics of the transmission of forces are given. The mechanism of the generation,form and development of plasticity domain in dam and bedrock are analyzed.