Assessment of Rockfall Hazards of Moziyan in Hechuan District, Chongqing, China

Moziyan is an area containing unstable rock masses located in Hechuan District, Chongqing, China and has constantly seen group-occurring rockfalls since 1964. The present study aims to investigate the damage of Moziyan rock mass and protect the mining areas and residential areas from rockfall phenomenon. Mohr–Coulomb model in FLAC–3D Program was built to find out the rockfall initiation position. RocFall program has been used to calculate the distribution curves of stopping positions, bounce height, total kinetic energy, and translational velocity of the falling blocks varying with horizontal distance. According to the simulation results, the stability of Moziyan rock mass is controlled by the unloading cracks behind the slope, and the falling blocks have a maximum bounce height and maximum total kinetic energy of 0 m and 2720.9 kJ respectively at the horizontal position of 461.6 m, where proper protection measures should be adopted to minimize the risk of the damage of the Moziyan rock mass. Conclusively, the results of simulation indicate that a barrier of 3 m height and 3000 kJ absorption capacity is enough to resist the falling stones with a maximum speed of 13.2 m/s at the horizontal position of 461.6 m.