Physical simulation study of crack propagation and instability information discrimination of rock-like materials with faults

Abstract

In coal seam mining, fault structures are easy to activate, which poses a serious threat to the safety of the mine during use. Therefore, the identification of physical information before fault activation and the prediction of fault activation have important guiding significance and reference value for the safety of coal mine production. For this reason, this paper first developed rock-like materials for simulating faults and surrounding rocks. On this basis, simulation experiments on the activation process of different types of analogical fault were carried out. The results showed that the failure process of rock-like samples with analogical concealed fault and analogical conduction fault could be divided into three stages, but the failure characteristics of each stage were different. The rock-like sample with analogical concealed fault began to crack in the form of tensile cracks at the structural tip, accompanied by the partial release of strain energy, and the whole sample was stable. In the crack initiation stage of the analogical surrounding rock, the analogical surrounding rock became the main bearing zone, the weak area of the analogical surrounding rock produced a tensile crack, releasing a small amount of strain energy, and the sample remained in a stable failure state. The rock-like samples with analogical conduction fault began to crack at the interface between the analogical fault and the analogical surrounding rock in the form of a shear crack, which released part of the strain energy. The sample had a sliding trend, but it was stable as a whole. At the stage of crack generation and propagation, new shear cracks appeared at the interface, which were affected by the released and secondary accumulated strain energy; some of the strain energy was released, and the sample was basically stable. In the early stage of sliding instability, which is the key period to prevent fault activation, the stress change was relatively stable, and less strain energy was released. In the later stage, the new shear cracks were connected with the existing shear crack, and the sample underwent sliding instability failure, which released a large amount of strain energy.