Effect Mechanism of Fractures on the Mechanics Characteristics of Jointed Rock Mass Under Compression

Abstract

Based on the theory of particle flow and the PFC2D program, a jointed rock mass model was constructed with a single-joint rock and angle joints of 0 $$^{\circ }$$ , 30 $$^{\circ }$$ , 45 $$^{\circ }$$ , 60 $$^{\circ }$$ , and 90 $$^{\circ }$$ . A universal testing machine was used for rock compression testing for an in-depth study of rock mechanical features during their destruction, allowing investigation into their macro- and micromechanical properties. Compressive tests were performed using numerical simulation to observe the generation and development of fissures and study their failure mechanics, so as to understand the entire process of crack generation, expansion, and penetration. The main findings are as follows: (1) Tension failure dominates the failure modes of specimens as showed by testing and numerical simulation; (2) The impact of the joints on rock mass strength depends strongly on their angle of inclination, which can destroy the original rock structure and result in major changes to rock mass strength; (3) No simple proportionality exists between joint angle and uniaxial compressive strength of specimen, but as the joint angle increases, uniaxial compressive strength increases and then decreases. (4) The forms of major fissures are highly similar and are mainly distributed near the ends of joints, with narrower fissure zones close to the end.