Elastoplastic finite element iteration method for stability analysis of three-dimensional slope

For the stability analysis of three-dimensional slope with known slip surface, based on the upper-bound theory of plasticity, an elastoplastic finite element iteration method for stability factor is suggested. The contact surface is simulated by rectangle element for plane problems or cubic element for dimensional problems with small thickness; and the Mohr-Coulomb associated flow rule criterion for the stresses is adopted. Based on analyzing the associated flow rule in the incremental elastoplastic theory, it is proven that the direction of the tangential stress on the slip surface and the sliding direction of the slope are consistent when the slope reaches ultimate state; so it is accurate that the tangential stress is regarded as the sliding force. In the process of calculation, the shear strength parameter is reduced step by step based on the iterative method, until the slip slope reaches ultimate state. Not only the stability factor can be got by this method rapidly, but also the tangential stress distribution on the slip surface and the deformation law of the slope can be obtained as well, which provides reference for taking reinforcement measures to the slope. At last two typical problems, i.e. ellipsoid slide and wedge slide, and a project example are given to verify its availability and rightness.