成渝中线高速铁路某隧道口崩塌运动特征研究

angerous rocks are developed at the entrance of a tunnel of Chengdu-Chongqing middle-line high-speed railway, and the instability will directly pose a great threat to the proposed line. Based on field investigation and real terrain data, this study used RocFall and RocPro3D software to simulate and analyze the two-dimensional and three-dimensional trajectory of a dangerous rock falling from a tunnel on the Chengdu-Chongqing Middle Line, and compared the trajectory characteristics of the two-dimensional and three-dimensional falling rocks. The results show that, under the two-dimensional motion simulation, the movement process of dangerous rock mass is mainly divided into five stages, namely, the steep slope slightly bouncing stage, the gentle slope slightly bouncing stage, the steep cliff obliquely throwing stage, the collision rolling stagnation stage and individual long-distance movement stage. The rockfall reaches the maximum kinetic energy of 3061 kJ and the maximum translational velocity of 18.15 m/s at the entrance of the tunnel. Three-dimensional simulation of rockfall movement is mainly divided into four stages, namely, small bounce stage on steep slope, rolling stage on gentle slope, oblique throwing stage on steep cliff and collision rolling stagnation stage. The maximum kinetic energy of 3D motion simulation is 4144 kJ, and the maximum translational velocity is 20.85 m/s. The 3D simulation trajectory is asymmetrically distributed along the slope with an offset ratio of 0.15. Moreover, the whole process of three-dimensional simulation of rockfall movement is similar to that of two-dimensional, and the total kinetic energy, velocity and bouncing height all reach the maximum in the steep cliff oblique throwing stage, but the maximum total kinetic energy, maximum velocity, maximum bouncing height and farthest moving distance of three-dimensional simulation of rockfall are greater than those of two-dimensional simulation results.