Micromechanical Modeling of a Dump Material

Micromechanical modeling of a fragmented claystone-a difficult waste material produced by open-pit coal mines in Northwestern Bohemia-is presented in this article. The PFC2D code, which accounts for the discrete nature of geomaterials and represents them as an assembly of unbonded or bonded particles, has been used. First, synthetic claystone was generated and the deformability and strength parameters were calibrated via numerical testing and comparing the results with those of available laboratory and field tests. The pre-peak, peak, and post-peak behavior of synthetic claystone was studied, and microscopic indicators of macroscopic behavior were selected and visualized. In order to simulate the dump material, joints were introduced that divided the claystone specimen into fragments. The appropriate microproperties of synthetic dump material were selected by means of a similar numerical testing and calibration procedure. Distribution and redistribution of particle contact forces before, during, and after failure of the dump material specimen were visualized and velocities corresponding to strain localization plotted. According to the study and some previous references, the compressive contact force chain acting in the direction of major principal stress appears as a backbone of microstructure, and compression induced tension as its basic failure mode at particle level.