Geologic disaster of rainfall-induced rock collapse and debris flow is an essential part of research in the field of geotechnical engineering. Based on the discrete element method, the article derived the constitutive model of particles bond-damage fracture-move. A two-dimensional slope model of rock mass collapse was established to simulate slide of rock mass collapse and dynamic evolution process of debris flow. The change of mechanics parameters of six monitoring points were tracked and analyzed. The results showed that, nonlinear motion of microscopic particles was obvious during the process of bond-damage fracture-move. Based on the geological conditions of rock mass collapse and debris flow on Greenland in Denmark, a three-dimensional slope model was established. The results showed displacements and velocities of measuring points both displayed linear relationship with slope when slope increased from 1.0 to 2.0; while non-linear capacity was strong under the slope with a degree above 2.0. The research will be the foundation for nonlinear movement of debris flow and this kind of disaster induced by different factors.
Key words: Discrete element method, rock mass collapse, microscopic failure, debris flow, numerical simulation.