Semi-analytical contact model for analyzing rock fragmentation induced by an indenter

Abstract

Rock indentation is the basic process in drilling and excavation from the mechanical points of view. A better understanding of the fundamental mechanism of rock-indenter interaction is of great significance. This paper proposes a semi-analytical model (SAM) to analyze rock fragmentation processes induced by indentation loads. In SAM, the analytical expressions of the stress and strain relationship of each two elements are obtained based on the theory of continuum mechanics. The numerical approaches including the conjugate gradient methods, fast Fourier transform, and fix-point iteration are applied to solve the unknowns of the model. In the proposed model, rocks are considered as elasto-brittle, and the damage threshold is described by the Mohr-Coulomb failure criterion. Also, a fracture element is treated as an inhomogeneity and tackled by the equivalent inclusion method. The present model can precisely capture the coupling between rock fragmentation and contact status. Thus, the developments of the crushed zone and cracked zone can be duplicated well. To reveal the potential applications of the model, the effects of confining pressure, rock inhomogeneity, and indenter geometry on rock indentation are also carefully investigated.