Abstract: Collapse of dangerous rocks is one of the most common geological dynamics hazards of high and steep shallow rock slope. It is sudden and strong, random, high speed and violent; so it is the focus of slope engineering survey. On the base of on-site investigation of dangerous rocks of Tibet Zhangmu Mountain, the distribution range of dangerous rock bodies is analyzed. The trajectory of collapse dangerous rocks, speed and characteristics of the body collapse accumulation of the different coefficients of friction is simulated by PFC3D in the condition of rainfall. The results show that the trajectory of collapse dangerous rocks is influenced by topography of slope, multiple impacts with the ground and repeated changes of direction, simplifying dimensional calculations may draw the wrong conclusions. Slope surface coefficient of friction affect the accumulation of forms of collapse of dangerous rocks, the smaller friction coefficient, the farther accumulation body position, and the easier performing flow state. Slope coefficients of friction 1.2, the simulation results are more consistent with the actual; The area of collapse dangerous rocks is the lower cliffs from Armed two camps to Zhangmu trench opening. PFC3D simulation of dangerous rocks collapse body movement can initially determine three-dimensional accumulation form and the influence scope, and provide a useful reference for disaster prevention and mitigation engineering design.

Key words: collapse of dangerous rocks, PFC3D, discrete elements, accumulation form, friction coefficients of slope