Experimental and numerical study on the mechanical behaviours of two rocks with circular openings

Abstract

The presence of discontinuities in rocks can significantly compromise the performance of the rocks in terms of strength and stiffness, thereby threatening the reliability and safety of engineering structures built in or on the rocks, for example, tunnels, and slopes. In this paper, a comprehensive set of experimental tests, including Brazilian disc tests and uniaxial compression tests, were performed for two distinct rocks including granite and sandstone with seven patterns of opening holes, in addition to intact rock specimens. To investigate the micro-cracks initiation and propagation, a hybrid continuum-discrete element method incorporating a cohesive fracture model was adopted to simulate the laboratory testing. The stress–strain relations, micro-cracks initiation and propagation, Young’s modulus, compressive strength, tensile strength and micro-cracks rate and orientation were discussed. The results showed that the presence of the holes could significantly influence the tensile strength, and compressive strength. However, its influence on the Young’s modulus was found to be relatively insignificant.