The joint dip angle has a significant influence on the mechanical behavior of coal, and revealing its influence mechanism is a scientific premise for analyzing mining‐induced mechanical behavior of coal mining. However, the geometric shape of coal joints is complex, and the previous research methods of artificially prefabricated cracks are difficult to accurately reshape the initial structural characteristics of coal. Therefore, the realization of the identification of the in situ occurrence of coal joints and the characterization of the distribution law is the basis for revealing the control effect of joint dip angle on mechanical behavior. Through the combination of CT scanning, three‐dimensional reconstruction, rock mechanics test and numerical simulation, the equivalent digital rock mass based on geometric probability distribution model is constructed, and on this basis, the control effect of joint dip angle on the mechanical behavior of coal body is studied. The results show that: (1) The average error of joint dip angle and bulk density between the equivalent digital rock mass and the actual coal sample is 2.26%, the error of uniaxial compressive strength is 14.17%, and the error of elastic modulus is 8.45%. The results are relatively consistent. (2) According to the sensitivity coefficient, the joints with an angle in the range of 45°–60° have the greatest influence on the uniaxial compressive strength. The joint angle in the range of 30°–45° has the greatest influence on the tensile and shear strength. (3) The influence degree of joint dip angle on the strength characteristics of digital rock mass is different. According to the sensitivity coefficient, the influence degree from strong to weak is shear strength, compressive strength, and tensile strength. (4) In terms of failure mode, different angles of joints have different control effects on different forms of fracture modes. Joints with angles of 45°–60° and 75°–90° play a major role in controlling the failure modes of model compression and tensile tests, respectively.
Lang et al. (Thu,) studied this question.