Abstract:The coupled analysis method of the trial load method and the 3D elasto-viscoplastic block element method is applied to analyze the stress and stability of Dahuashui arch dam. In the analysis,the foundation is divided into block elements,and the arch dam is treated as an arch-cantilever system. On the interface between the dam and foundation,it is assumed that the base nodes of the dam are fixed on the surface of the block elements. So the displacements of the base nodes have relationship with the displacements of the block elements. According to the virtual work theory,the stiff coefficients about the displacements of the base nodes are transformed into the stiff matrix of the block elements. After assembling all stiff matrixes,the total equilibrium equation can be established. Then it can be solved to obtain the displacements of the interior nodes of the arch dam and those of the block elements of the foundation. Then the stress and stability status can be analyzed separately. The calculation results indicate that the dam abutment slope is stable on the whole.