Abstract: This study introduces the main function, technical index and instrument composition of a developed rock multi-functional shear test system in detail. A series of mechanical experiments is carried out by using the testing system. This system mainly consists of three parts: testing device, measurement system and control system. The maximum normal tensile stress is 40 MPa, and both the maximum normal compressive stress and horizontal shearing stress are 120 MPa. The specimen size is 50 mm?50 mm?50 mm. Multiple mechanical experiments are conducted on granite, including direct tension test, direct shear test, tension-shear test and compression-shear test. The results show that brittle fracture of the specimen occurrs in the direct tensile tests. The acoustic emission (AE) signal instantly reaches the peak and the fracture surface exhibits the characteristics of tensile fracture. In the direct shear test, the specimen is destroyed many times. The AE signal suddenly increases at the moment of destruction, and the fracture surface shows the characteristics of shear fracture. In the tension-shear test, the shear strength of the specimen decreases significantly under the tensile stress. The AE signal is obvious at the failure stage, and the fracture surface exhibited both tensile and shear fracture characteristics. The results of the above mechanical experiments indicate that the developed multi-functional shear test system can successfully carry out a variety of mechanical experiments and provide a new testing method to further study shearing properties of rocks.

Key words: rock mechanics, shear test, tension-shear test, test system, acoustic emission