Experimental Study of Mechanical Properties and Fracture Characteristics of Conglomerates Based on Mohr–Coulomb Criteria

Abstract

Gravel is one of the main factors affecting the mechanical properties of conglomerates, which plays a decisive role in crack propagation. In this paper, taking the conglomerate of the Baikouquan Formation in Mahu Sag of Xinjiang as the research object, a three-dimensional model of the conglomerate is constructed by the discrete element numerical simulation method, and the triaxial compression experiment under different confining pressures is simulated. The mechanical properties and fracture morphology of conglomerate are analyzed with gravel content as a variable and verified by laboratory tests. In this simulation, with the increase of gravel content, the compressive strength of the conglomerate decreases, angle of internal friction decreases, and the fractures show different forms. The results show that the gravel morphology, spatial location, and gravel content have an impact on the mechanical properties of the conglomerate. The gravel content affects the formation process of the dominant fracture surface by controlling the distance between gravels so as to control the internal friction angle and it is the main controlling factor for the mechanical properties of the conglomerate. Gravel cracks initiate at the edge of gravel. Stress controls the formation of main cracks under low gravel content, and the influence of gravels under high gravel content makes cracks more discrete and complex.