Failure mechanism analysis of rock in particle discrete element method simulation based on moment tensors

Abstract Acoustic emission (AE) and moment tensor simulation with discrete element method (DEM) have been proven to be an effective method to analyse the failure mechanism of rock. The ratio (R) of isotropic and deviatoric components of moment tensor is often used to distinguish the failure mechanism of AE events. However, the critical value of R to distinguish different failure mechanism has not been strictly verified, and the method to evaluate the fracture mechanism of macrocrack qualitatively by the failure mechanism of AE events is not clear enough. Therefore, we analyzed the theory of moment tensor with DEM to distinguish failure mechanism and verified this theory by a simulated verification test with four particles and six particles model in 2D and 3D respectively. Furthermore, we simulated three typical laboratory tests of rock. Results show that the critical values of R for distinguishing implosion, shear, and tensile mechanisms are equal to ±40 in 2D and ±35 in 3D. Using the modified critical values of R to identify the failure mechanism of rock is more accurate than counting the microcracks. The fracture mechanism of the macrocrack can be determine quantitatively by the distribution curve of AE events around this macrocrack.