2-D nonlinear FEM analysis for underground openings locatedin the layered rock mass with softening joints

A FEM model was established for the layered rock mass with softening joints. A method was put forward in which the layered rock mass and the soften joint were simulated by transversal isotropic material and a kind of rotational Goodman interface element was proposed to simulate the behavior of interface between the softening joint and the layered rock mass. The results of FEM were compared with the date measured in situ and it is shown that they matched with each other very well,so that this kind of analytical method is rational. 