Objectives Rockfall occurs frequently in the mountainous areas of southwest China, which is easy to cause huge casualties and property losses. A rapid simulation method of the collapse process is urgently needed. At present, the commonly used collapse simulation software still has obvious shortcomings, such as low terrain accuracy, failure to consider the structural characteristics of rock mass, failure to realize block collision and fragmentation, etc., and the logic operation based on central processing unit (CPU) limits the calculation speed. A new method for rapid simulation of the three-dimensional motion process of collapse is proposed.

Methods The unmanned aerial vehicle (UAV) aerial photography modelling combined with field investigation is used to obtain the slope surface model and determine the characteristic parameters of rockfall. The simulation software of large-scale collapse movement process is developed using Unity3D platform which integrates PhysX physics engine and central processing unit-graphics processing unit (CPU-GPU) parallel computing capability.

Results The software can reproduce the whole process of collapse-impact-fragmentation-accumulation. It can output the three-dimensional trajectory, velocity, energy and jumping height of collapse, which provides reliable basis for the design of collapse prevention and control. Taking Xiejiayan collapse in Nayong, Guizhou Province as a prototype case, three-dimensional simulation and verification of the collapse movement process are carried out. The simulation results of the rockfall accumulation range are in good agreement with the field investigation of the rockfall accumulation range at the bottom of the slope, and the movement characteristics of the simulated single block rock conform to the real physical laws, which indicates the feasibility and practicability of this method.

Conclusions This method can solve the problem of simulation, analysis and visualization of the whole process of three-dimensional movement of rockfall.