Discrete element approach to determining rock mass pressure on ore pass walls

Abstract

A critical safety factor of ore pass walls is the correct evaluation of rock flow pressure on the walls at the design stage. This study uses the discrete element method to determine load of rock flow on the ore pass walls. This method is the most effective in modeling ore flow through a trapdoor. On the other hand, modeling of each discrete particle can create an illusion that the model automatically takes into account all typical phenomena of granular medium. From this point of view, the method of discrete elements can be discredited in practice. Therefore, it is necessary to describe the methodology of constructing and correcting the discrete element and finite element models of ore passes. At the first stage, the grain size distribution of rock flow is analyzed, and the representative sample volume is determined. At the second stage, the shear tests are performed at the particle–particle and particle–ore pass wall contacts. It is required to implement both tests as the difference between internal and external friction angles can be assumed to be the cause of bridging (a silo phenomenon). At the third stage, due to essentially different kinematics of shearing andconical pile formation, the calibration criterion is chosen to be the angle of repose. The fourth stage is the bridging modeling and comparison of the model data with the analytical results. This stage is only limited to the numerical modeling as there are yet no fully developed techniques to reconstruct bridging in ore passes on a laboratory scale. At the fifth stage, the numerical experiments on filling an ore pass and on ore outflow from it are carried out. The results are transferred to a finite element method program.