Abstract：The stability of rock slope is mainly determined by its discontinuity and rock bridge. However，the failure mechanism of discontinuity and rock bridge has not been studied comprehensively. In this paper，the stability analysis of jointed rock slope is carried out by shear strength reduction finite element method. The elastic-perfectly plastic material is adapted in the finite element method. With the strength reduction，the nonlinear FEM model of jointed rock slope reaches instability，and the numerical non-convergence occurs simultaneously. The safety factor is then obtained by strength reduction algorithm. At the same time the critical failure surface and overall failure progress are found automatically. The numerical convergence or non-convergence is related to the yield criterion. Comparison is made of several yield criteria in common use. The Mohr-Coulomb criterion is undoubtedly the best-known criterion. But its yield surface is an irregular hexagonal cone in principal stress space. It brings difficulty to numerical analysis. For convenience the Mohr-Coulomb criterion is replaced by Mohr-Coulomb equivalent area circle yield criterion. Through a series of case studies，it is found that the safety factor obtained by strength reduction FEM with Mohr-Coulomb equivalent area circle criterion is fairly close to the result of traditional limit equilibrium method (Spencer’s method). The result shows that the discontinuity coalescence pattern is influenced by its strength，length，location，and obliquity. The failure occurs 'naturally' through the zone in which the shear strength of rock is insufficient to resist the shear stresses. Through a series of case studies，the applicability of the proposed method is clearly exhibited. This study presents a new approach for stability analysis of jointed rock slope，and it is especially available to the complicated geological condition and supported slope.
