A critical condition of the zonal disintegration in deep rock masses: Strain energy density approach

Abstract

The deformation and failure modes of the deep rock mass are different from those of the shallow rock mass. Zonal disintegration phenomenon occurs in the deep rock mass, while loosened zone, plastic zone and elastic zone appear successively in the shallow rock mass. It is known that it is necessary to adopt the different support system for the different deformation and failure modes of rock mass. Therefore, it is very significant to define the critical condition of zonal disintegration. In this paper, a non-Euclidean model is proposed to investigate the critical condition of zonal disintegration in deep rock mass. A bulk free energy function of deep rock mass is introduced to describe the effects of microcracks. The standard formalism of non-equilibrium thermodynamics is used to obtain an equation for the non-Euclidean parameter. The relationship between non-Euclidean parameter and stress is established. The critical value of stress for zonal disintegration is derived using strain energy density approach. When the external load is less than the critical value of stress, the mechanical behaviors of rock materials can be simulated using the classical elastic model. In other words, when the external load is less than the critical value, zonal disintegration phenomenon does not occur. When the external load exceeds the critical value of stress, the mechanical behaviors of rock mass can be simulated using the non-Euclidean model, and zonal disintegration phenomenon occurs.