English：

In the construction of a tunnel in a jointed rock mass, the stability of the surrounding rocks isclosely related to the joint combination conditions. To deeply understand the relationship between thestability of surrounding rocks and joint characteristics during tunnel excavation, based on the Wugongshanand Longnanxi Tunnel Projects under construction in Ganzhou City, Jiangxi Province, the calculationmodels of different joint inclination angles are established by means of discrete element simulationanalysis. Taking the shear stress distributions of collapse area, collapse site, and surrounding rock as theresearch objects, the possible instability risk and instability mechanism of surrounding rocks underdifferent joint inclination angles were studied, the instability modes and collapse areas were summarized,and the corresponding risk control measures were proposed. The following conclusions are obtainedthrough the research that under the combined conditions of two groups of joints, the instability ofsurrounding rocks can be divided into four modes, namely, bending failure mode, bedding slip mode,vault collapse mode, and vertical collapse mode. The occurrence, location, and range of collapse risk arecontrolled by joint inclination angle. The 0°/ 90° inclination angle combination has the greatest influenceon the stability of surrounding rocks, followed by the symmetrical joint combination. Nonlinear fitting canbetter predict the collapse area. The bolts should be arranged for the possible instability parts, and thelayout angle should intersect with the large angle of the joint group as much as possible, focusing on the scope of the collapse and the joint opening area. The results indicate that the instability of surroundingrocks with joint inclination can be summarized into four fixed modes,which are controlled by thecharacteristics of joint inclination.