Axisymmetric Failure Mechanism of a Deep Cavity in Layered Soils Subjected to Pore Pressure

Abstract

To investigate the roof stability of deep cavities in layered soils, an axisymmetric failure mechanism based on the existing mechanism is proposed. Because deep cavities are generally under the water table, the adverse effects of pore pressure are taken into account. Limit analysis of the failure mechanism was conducted on the basis of the nonlinear power-law failure criterion, and upper-bound solutions of the failure curve were obtained. The procedure for the numerical calculation of the failure mechanism is proposed and the consistency of the failure mechanism is demonstrated. The roof failure involving two soil layers is discussed in detail to explain thoroughly the roof stability of deep cavities and tunnels in layered soils.