Particle flow simulation of the influence of granite crystal size distribution on acoustic emission characteristics

Based on the discrete element theory and PFC2Dsoftware，the grain-based model and the moment tensor the⁃ ory are combined to simulate the influence of the heterogeneity of the microstructure in the uniaxial compression exper⁃ iment on the acoustic emission characteristics of the rock. It reveals the inhomogeneity caused by the distribution of crystal sizes affects the fractal dimension，fracture strength and b value of the spatial location of the acoustic emis⁃ sion event in the rock fracture process.The main research conclusions are as follows:1 the heterogeneity of the meso⁃ structure has a great influence on the acoustic emission activity of the rock. With the increase of the number of micro-cracks that constitute an acoustic emission event，the number of acoustic emission events rapidly decreased，and the two parameters above have a negative exponential function relationship.2 The more uneven the crystal particle size distribution， the greater the heterogeneity of the rock and the worse the uniformity of the stress field distribution，the earlier the acoustic emission activity of the rock and the earlier the formation of micro-cracks，the low⁃ er the initiation stress. Crystal size， stress field distribution， micro - cracks and acoustic emission events are an influence chain.3 As the heterogeneity factor increases，the b value of acoustic emission activity gradually decreases， and the proportion of large-scale micro-fractures in the rock increases.There is a good linear relationship between the acoustic emission b value and the heterogeneity factor H.4 When the heterogeneity factor is large，the acoustic emis⁃ sion events with large fracture strength tend to concentrate on the main fracture surface.As the heterogeneity factor in⁃ creases，the self-similarity of the spatial location of acoustic emission events increases，and the fractal dimension of the spatial location of acoustic emission gradually decreases.The fractal dimension and the heterogeneity factor have a pow⁃ er function relationship. This research method effectively makes up for the shortcomings of indoor acoustic emission tests，and provides an effective technical means for revealing the intrinsic effect of mesostructure heterogeneity on rock acoustic emission activities.