Numerical Simulation Of Loess Collapse Based On Distinct Element Method

Loess collapse is a kind of geological phenomenon, which refers that the loess mass collapses and separates from the matrix of the high and steep slope in the action of gravity and external force, and is more common in loess area as a harmful disaster. In order to analysis and calculate the failure process of loess collapse reasonably, and provide the basis for guiding the disaster prevention and reduction work effectively, building a collapse stability calculation model is now a needed urgently core topic.The formation factors of loess collapse mainly include the slope geometry, soil properties,geological structure plane, etc. According to the characteristics of sliding loess collapse and failing model, this paper used the DEM(Distinct Element Method) to make a mechanical analysis for collapse mass, and calculated its motor process, also combined with the computer graphics technology for visualization. It mainly includes three aspects of the research content:the construction of discrete element model for the loess slope, the force-displacement calculation of blocks and visualization for all units. Among them, block division is an important link of the construction of discrete element model, and the rationality of the division results will affect the accuracy of collapse process simulation. In view of traditional DEM, considering dividing blocks in same size may neglect the actual failure characteristic of collapse, this article used the model of sliding surface in logarithmic spiral shape to optimize the segmentation process, which made its result more reasonable.This paper took a loess collapse case for example, which located in Matou village,Pingtou town, Chencang district of Baoji city, Shaanxi province, then made a numerical simulation and analysis of its failure process. Based on the simulation results, the deformation and failure process of the collapse can be summarized to four stages: split of vertical joints—slope deformation and instability — the movement of collapse block —the accumulation of collapse body. By analyzing the displacement change trends of nine feature points in loessslope, it can be seen that the displacements of front collapse blocks are larger than the hind blocks’. Meanwhile, the vertical displacement change trend is interrelated to slope’s altitude positively, which is more consistent with the actual failure law of collapse. The instance calculation shows that, the calculation model above can provide theoretical guidance for the prevention and warning of collapse disasters, and has vital theoretical and practical significance.