Micromechanics-based model of rock considering compaction deformation: Analysis of microcrack influence from discrete and continuous perspectives

Abstract

This paper proposed a micromechanics based constitutive model of rock considering compaction deformation, incorporating the intricate failure mechanisms of microcracks (i.e., opening, closing, friction, and slip) along with the overall deformation processes of rock (i.e., compaction, elasticity, plasticity, and damage). By combining the proposed continuum constitutive model with a discrete element numerical model featuring gapped flat joint contacts, the influence of initial cracks and crack volumes on rock compaction deformation was comprehensively analyzed from both discrete and continuous perspectives. Our findings reveal that the mechanical properties of the rock can be influenced by both the number and volume of cracks. The product of these two factors determines the overall void ratio, while the number of cracks exhibits an exponential relationship with the deformation resistance of the void under fixed void ratios. Furthermore, we observe that higher confining pressures result in reduced compaction deformation, and the compaction process is independent of force directionality. The comprehensive analysis from both continuous and discrete approaches offers a profound understanding of compaction deformation mechanisms, improves the identification efficiency of discrete compaction parameters, and enables the analysis of increased compaction deformation due to changes in crack states under external conditions (e.g., high temperature).