Study on the characteristics of spatial and temporal evolution of sandstone fracture under uniaxial compression

The real-time acoustic emission test of sandstone under uniaxial compression is carried out by using PCI-II AE monitoring system and high-speed camera.Combined with the information of AE parameters,the evolution characteristics of AE parameters with rock deformation are analyzed, from which the failure precursor information is identified.According to the AE characteristics, the temporal and spatial evolution pattern of micro-cracks is revealed.The experimental results show that the parameter values are abrupt at the yield strength, AE activities with high-level amplitude are appear, which are higher than 80 dB; the concentrated occurrence of high-energy-level and high-magnitude events inside the rock is indicative of increased local damage degradation; other types of rupture have also begun to increase, but most of AE events with energy level greater than 4 are almost tensile rupture types.The above characteristics phenomena can all be used as the precursor information of rock failure.