Numerical Simulation Study of Crack Development Induced by Transient Release of Excavation Load during Deep Underground Cavern

Abstract

The cracking and developing of structural surfaces is one of the main causes for surrounding rock mass large deformation and failure in deep underground cavern excavation. A numerical simulation method for discontinuous structural surface development is proposed based on the transient unloading of excavation load during underground cavern excavation. The program will automatically evaluate every substep in the dynamic calculation, and determine if the development stops and the cracking direction based on dynamic fracture mechanics. The penalty function is adopted to simulate the opening and sliding characteristic of structural surfaces. And the cracking path would be shown by iterative calculation. Results show that, the lateral pressure coefficient (LPC) is the main factor of cracking direction. When structural surface is shallow to the side wall, the crack would develop to the surface of the side wall. When it is deep enough into the side wall, the cracking might stop before it goes to the surface of the side wall. The accuracy of this simulation is verified by the comparison to relative laboratory tests.