Influence of Joint Angle on the Acoustic Emission Evolution Characteristics and Energy Dissipation Rule of Rock Mass

The existence of joints leads to great changes in the mechanical properties of rock mass, which is more likely to induce tunnel rockburst and other disasters. Therefore, it is of great significance to study the mechanical properties of jointed rock mass for the safety construction of tunnels and other projects. In this paper, based on the particle discrete element model, some rock samples with different angles are established. Firstly, the influence of joint angles on mechanical strength properties, acoustic emission evolution characteristics and energy evolution law of rock mass are analyzed. Secondly, the damage constitutive model of jointed rock mass is established based on acoustic emission parameters and dissipation energy parameters. The research results show that with the increase of joint angles (from 15 degrees to 90 degrees), the peak strength of jointed rock samples increases first and then decreases, as V-type. The failure modes of jointed rock samples can be divided into two types, namely H-type failure mode and Y-type failure mode. The joint angle has little effect on the AE evolution characteristics of rock samples, but the maximum count rate of AE and the number of high count of AE are influenced by different joint angles. With the increase of joint angle, the required boundary energy and dissipated energy for rock sample failure decrease firstly and then increase. The mechanical properties of rock mass analyzed by energy method can better reflect the nature of its failure characteristics. However, it is difficult to monitor the energy change of rock in reality, so it is feasible to use acoustic emission characteristics to reflect the stability of rock mass.