MECHANICAL PROPERTIES AND AE CHARACTERISTICS OF UBIQUITOUS JOINTED SPECIMENS UNDER COMPRESSION SHEAR LOAD

The mechanical properties of jointed rock mass are of great significance for guiding engineering design and construction. In order to study the effect of the combined joint parameters on mechanical properties of specimens,we conducted compression-shear tests. We used rock-like materials to prefabricate ubiquitous jointed specimens with different joint inclinations and spacings. During the test,we used high-definition camera to record the failure characteristics of ubiquitous jointed specimens. We divided the specimen's failure modes into three types: plane shear failure,quasi-integrity shear failure and oblique shear failure. The results show that the joint spacing can change the failure mode of specimens and the joint inclination determines the failure mode of specimens. Then,we analyzed the peak shear strength of specimens with different joint parameters. The results show that the weaken degree of ubiquitous joint on the shear strength reaches 15.95% ~56.62%. The peak shear strength of jointed specimens gradually increased with the joint spacing's increase,and had the first increase and then decrease trend with the increase of the joint inclination. In addition,we used the acoustic emission(AE)device to monitor the specimens' loading process in real time to analyze the AE characteristics of specimens with different joint parameters. During the compaction phase,the AE maximum impact number for jointed specimens increases as the joint spacing decreases. For the AE energy characteristics of specimens,the peak energy of jointed specimens decreases with the joint spacing's decrease,but the mean energy increases with joint spacing's decrease. As the joint inclination increases,the jointed specimens' peak energy and mean energy both increase first and then decrease.