Experimental investigation on the mechanical properties of thermally damaged granite specimens containing pre‐existing holes

Abstract

AbstractA comprehensive understanding of the mechanical behavior of thermally damaged rock is crucial for the design, prediction, and stability control of rock engineering. However, the strength and fracture characteristics of rock containing pre‐existing flaws have not been studied systematically. Therefore, in this study, uniaxial compression tests were conducted on preholed granite specimens using MTS816 rock mechanics testing and acoustic emission (AE) monitoring systems. The mechanical properties, AE characteristics, and failure patterns of thermally damaged granite specimens were analyzed, and the alteration of the mechanical behavior was explained by the P‐wave velocity, effective porosity, mineral components, and thermal cracking. The results show that the peak strength and elastic modulus of preholed granite specimens first increased and then decreased with the increasingly high temperature. Cracks were always initiated from the left and right perimeters of the pre‐existing hole, and the crack coalescence modes between the two pre‐existing holes were independent of the high temperature. After 150°C treatment, thermal cracks were observed, and the complexity and interconnectivity of the fracture surface increased with temperature. The variations of the mineral component and crystal structure induced by increasing the high temperature contributed to the thermal damage of the granite. The experimental results are expected to enhance the understanding of the macromechanical and mesomechanical behaviors of rock with respect to high temperature.