Experimental and Numerical Study of Joint Persistence Effect on the Non-persistent Jointed Rock Mass' Tension Failure Behavior

Tension failure is a common failure mode for jointed rock mass, with the rock bridge as the main body subjected to the tensile load. To reveal the jointed rock mass stability, the influence of joint persistence (JP) on the tensile capacity and failure behavior of rock bridges is investigated. Considering different JP, the direct tensile test is performed on cubic jointed rock-like specimens using a newly developed direct tensile apparatus. During the failure, an AE detector and a thermal infrared imager are used to monitor the parameters (e.g., AE and temperature). Furthermore, an RFPA3D numerical program validated by the laboratory results is proposed to further investigate the tensile behavior of rock bridges. The results show crucial precursory properties of the AE parameters, indicating that they can be used to discriminate and monitor the failure process under various JP conditions. The temperature response to tension failure is not apparent. With increased JP, the equivalent tensile strength of rock bridges and the weakening degree of rock bridges exhibit a W-shaped variation trend due to the size effect and boundary effect. The load moment effect must be considered under a large JP, and the effect of JP on the rock bridge tensile strength needs to be considered when determining the safety factor for jointed rock mass stability. This study can contribute to a better understanding of JP, thus promoting the analysis of jointed rock mass stability. Direct tensile tests on cubic rock-like specimens were conducted on a novel test apparatus.Effect of joint persistence on tension failure behavior was investigated.AE and thermal infrared imager were utilized to analyze the tension failure mechanism.The rock bridge's tensile strength exhibited a "W-shaped" trend with joint persistence increasing.