Stability analysis method for arbitrary slip block based on dynamic finite element method

A hybrid method which combines the finite element method and the limit equilibrium method is proposed to evaluate the dynamic stability of slopes or dam foundations under earthquakes. It is used in the stability analysis for dam abutment of Shapai arch dam under “5.12” Earthquake subsequently. The proposed method can cut arbitrary slip blocks with different structural plane combinations from ground surface triangular mesh. And then the block is meshed automatically. The block mesh is independent of finite element calculation mesh. Based on the stress field of static and dynamic FEM calculations, the stress field of all slip surfaces of the block is obtained by interpolating stress on block mesh. By integrating stress on block faces, the slip force and anti-slip force can be calculated, and then the safety factor of slip block is computed by means of the theory of the limit equilibrium method. The advantage of limit equilibrium method is that it can provide safety factor with specific meaning, but it cannot provide instant safety factor for slip blocks during the whole seismic action. A new algorithm of automatic mesh generation for slip blocks is employed by the proposed method which combines the advantages of the limit equilibrium method and the finite element method. It provides a new way for analytical technique of dam abutment stability evaluation. The examples show that the calculated results by the proposed method is reasonable and applicable in engineering practice.