Non-Linear FEM Analysis for the Layered Rock-Mass Tunnel Based on the Twin Shear Strength Criterion

According to the geotechnical conditions, A FEM model has been established to analyse the mechanical characteristics of the highway tunnel in the layered rock mass. In this model the layered rock mass and the soften joint are simulated by the transversal isotropic material, the interfaces between layers are simulated by the element of rotational Goodman interface, but the interface between the lining structure and surrounding mass is proposed to simulate by an interface element with thickness, and the supporting of tunnel is simulated by the straight beam element. In the meantime, based on the twin shear strength criterion, the mechanical characteristics of rock, the stiff matrix of element for the layered rock mass, soften joint and interface have been discussed. The analytical model has been demonstrated by comparing the results of layered surrounding rock-mass FEM with the test data in situ.