Analysis of rupture mode and acoustic emission characteristic of rock and coal samples with holes

Abstract

Abstract In order to understand the rupture mechanism of rock and coal samples with holes, the acoustic emission (AE) tests of rock and coal samples with holes under uniaxial compression are done. Through the AE tests, the basic mechanical and AE variation rule of two samples in the total rupture process are obtained, the dynamic rupture process was observed and finally the spatial evolution and multi-fractal characteristic of AE are analyzed. The results show that the variation rule of AE events of two samples are coincident with the variation rule of stress. The uniaxial compressive strength of a rock sample with a hole is about five times than that of a coal sample with a hole, and the maximum AE pulsing counts (AEPC) of a rock sample with a hole is much larger than that of a coal sample with a hole. Due to the variation of lithology, the dynamic rupture process and the spatial evolution rule of AE events of rock and coal samples with holes are obviously different. But the distributions of the three-dimensional locations of the two samples are coincident with the macroscopic rupture morphology. Both of them have multi-fractal characteristic in the process of rupture, the multi-fractal spectrum width Δf(α) at the time of rupture is smaller than that before rupture and the Δf(α) before rupture is smaller than that after rupture. This indicates that the energy (E) before and after rupture is smaller than that at the time of rupture, the E after rupture is smaller than that before rupture and the E of a coal sample with a hole in each stage is less than that of the corresponding stages of a rock sample with a hole.