Influence of Confining Pressure on Strength Characteristics and Brittleness of Granite and Its Characterization

Confining pressure is one of the main factors affecting rock mechanical properties. In order to study the effect and mechanism of confining pressure effect on the strength and brittleness characteristics of granite, this paper takes Sejilashan granite as the research object, carries out indoor triaxial compression tests under different confining pressure conditions, obtains the variation rule of strength parameters such as failure form and peak stress, and constructs a triaxial constitutive model considering the confining pressure effect within the framework of unified strength theory. Based on the total stress-strain curve, an evaluation index of rock brittleness characterized by fracture energy was established to determine the quantitative relationship between confining pressure and rock brittleness. On this basis, RPFA software is used to simulate the whole process of failure and acoustic emission evolution characteristics of granite under different confining pressures, so as to reveal the damage evolution mechanism of granite. The results show that the confining pressure can effectively limit the formation and propagation of microcracks in granite, and then significantly improve the macroscopic strength and deformation properties of granite. The triaxial constitutive model and brittleness evaluation index established in this paper can effectively reflect the law of confining pressure effect on rock strength characteristics and brittleness.