Abstract: The fracture of the rock bridge is a discontinuous deformation phenomenon. Strength reduction method, although it is the mainstream approach for progressive failure process simulation, it can not describe the discontinuous deformation phenomenon. The connectivity rate reduction method and the stiffness reduction method are proposed to simulate the progressive failure process of the rock block bounded by the coplanar non-persistent joints, and a block stability analysis method considering the progressive failure process is established. Firstly, the Goodman element is introduced to describe the rock bridge part and the fracture part of the coplanar non-persistent joint. The stress of the rock bridge element and the fracture element in the slip surface is solved by the equation of static equilibrium. Secondly, Griffith criterion is used to judge the failure for rock bridge element, and the connectivity rate reduction method is used to describe its rupture. The MC criterion is used the to judge the failure for fracture element, and the stiffness reduction method is used to describe its yield. By cyclic iteration, rupture process of the rock bridge element and the stress redistribution process of the fracture element to realize the simulation of the progressive failure process of the whole slip surface. Then, the limit state of the slip surface is redefined considering the progressive failure process, and the slip surface is pushed to the limit state by the weight overload method. Based on the theoretical framework of the limit state design, the safety factor of the block stability is calculated. The results of the engineering examples show that the simulation results of the progressive failure process are consistent with the field survey results. The simulation of the progressive failure process is helpful to the analysis of the deformation mechanism of the rock slope from the qualitative analysis stage to the quantitative analysis stage.

Key words: rock slope, convex block, coplanar non-persistent joint, connectivity rate reduction method, stiffness reduction method, Goodman element, limit state design, weight-overloading factor of safety