Seminar

Rock deformation and failure occur at different scales. An advanced two-dimensional numerical model has been developed to account for rock deformation and failure observed in laboratory tests from the mineral scale. The model is established on the principle of representing mechanical and geometrical properties of the real rock. Mechanical formulation includes five parts, namely, (1) the entity of the rock is composed of rigid, unbreakable balls; (2) each mineral grain consists of several balls which are glued together by the parallel bonds (PB), (3) grain-grain boundary is mimicked by substituting the PB with the smooth joint contact (SJ); (4) the effect of strength degradation with the presence of intra-grain cracks is reflected by weakening PB properties; and (5) de-bonding of a ball-ball bond (PB or SJ) corresponds to the generation of a crack, which intrinsically models the micro-cracking process related with rock deformation and failure. The geometrical information of grain boundaries is deterministically obtained via digital image processing (DIP), and that of the intra-grain cracks is reproduced in a statistical way based on examination of thin sections. The proposed rock model has the advantages of capturing the heterogeneity of rock at the grain scale, and revealing the mechanism of deformation and failure by explicit simulation of the micro-cracking process.