AUTHOR=Chen Qingzhi , Liu Yuanming , Wang Wei , Ou Xun , Zhou Yuhang , Teng Zhaolei , Tian Xingchao 

TITLE=Effects of Normal Stress and Joint Inclination Angle on Rock Failure Characteristics Under Compression–Shear Conditions

JOURNAL=Frontiers in Earth Science

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.950648

DOI=10.3389/feart.2022.950648

ISSN=2296-6463

ABSTRACT=In this paper, cement mortar was used to make specimens containing groups of parallel joints with different inclination angles to simulate natural rock mass, and the specimens were subjected to shear tests under different normal stresses. By analyzing the crack propagation path, failure modes and strength characteristics of these rock specimens, the effects of normal stress and joint inclination angles on the strength and failure characteristics of this type of rock mass were studied. These following conclusions were drawn from this paper: (1) When the inclination angles of the joints were 0° and 15°, the changing of the normal stress did not affect the failure mode of the rock mass. The rock mass were mainly in the mode of shear failure, the increasing of the normal stress only increased the spalling area of the rock mass. (2) When the inclination angles of the joints are 30°, 45° and 60°, with the increasing of the normal stress, the number of those approximately parallel cracks in the specimens increased, the friction marks caused by shearing increased, and the failure mode of rock mass changed from tension failure to tension-shear composite failure. (3) Under different joint inclination angles, the propagation and penetration paths of cracks generated in the rock body were different. With the increased of the joint inclination angles, the angles α and the angle β tended to decreased. (5) The shear resistance of the rock mass was affected by the undulation angle of the joints and the normal pressure. The shear resistance of rock mass was improved due to the increasing of normal stress. Within a certain range, with the increasing of the inclination angles of the joint, the shear resistance of the rock mass tended to decrease first and then to increase.