Modelling of progressive failure mechanism of mine pillars

Abstract

Abstract Rock fracturing process around underground openings is mainly a process of progressive slabbing with the generation of surface-parallel fractures in the initial stage, and shear failure is likely to occur in the final process. The difficulty of capturing this behaviour through conventional continuum modelling has led to the development of advanced constitutive laws for use in continuum models. Recently, an enhanced continuum constitutive approach to simulate strain-softening based on the Hoek-Brown failure criterion has been presented. This advanced Hoek-Brown model with Softening introduces a hyperbolic decay of the material properties affecting the post-peak response and the nonlinear dilation, thus enabling to investigate failure modes in the form of dilatant shear bands. Moreover, to restore the objectivity of the numerical solution during the development of strain localization phenomena, a viscous regularization technique has been implemented within the model. The performance of this constitutive model has been proved and, in this paper, further numerical computations are reported concerning the brittle failure process occurring in mine pillars, thus confirming the capability to capture failure mechanisms during excavation within a strain localization regime.