Failure mechanism of rock specimens with an elliptical pre-hole under different stress conditions

Abstract

This paper conducted a load test on rock specimens containing an elliptical pre-hole using a combination of numerical simulation and theoretical solutions of linear elasticity. The aim is to investigate the impact of elliptical geometric parameters and stress conditions on the rock failure process while considering a consistent hole area. Additionally, laboratory experiments incorporating digital image correlation (DIC) techniques were used for verification. This result indicates that the impact of elliptical geometric parameters is primarily observed during the early stage of loading, while it has minimal influence on the deterioration effect and failure mode of rock specimens during the later stage of loading. Regarding the inclination angle, as its value increases, the pure tension region near the hole diminishes, and the failure point on the hole's edge shifts from the coordinate axis direction to the inclination direction before returning to its original direction. Regarding the axis ratio, as the value decreases, the pure tension region diminishes at small angles, while the opposite occurs at large angles. Confining pressure affects the whole loading process. The greater the confining pressure, the smaller the tensile stress in the rock specimen, the more the tensile failure mode is suppressed, and the larger the rock specimen strength is.