Acoustic emission testing of nonuniform stress in strata near reverse faults and numerical analysis of stability of roadways

The concentrated stress and fractured rock around the fault zone, have great potential safety hazards for the section layout of a roadway and its maintenance, so the distribution of in-situ stress and the failure mode of the surrounding rock near the fault and their influences on the roadway stability should be necessarily grasped. The upper and lower plates of the reverse fault in Huainan Coal Mine are chosen for tests. The in-situ stress fields and rock failure modes are tested by the MTS experimental system and acoustic emission. The stability of roadway near the fault under different in-situ stresses is analyzed by ANSYS. After rock mechanics experiment, it is found that the scale of fractured sandstone is smaller and its AE events number is more, while the size of fractured mudstone is larger and its AE events number is less. According to the measured results of ground stress, it is found that the in-situ stress near the fault is dominated by the tectonic stress. The overall force of the lower plate is large due to the upper plate extrusion. After roadway excavation, the stress drop zone of the secondary stress appears in a certain range around the roadway, and the scope of drop zone is close to the range of fractured surrounding rock. At the same time, with the expanding range of stress drop zone and decrease of the initial stress, the moving of rock strata and expanding of fracture range of the surrounding rock are violent. According to the plastic distribution of the surrounding rock and the movement of rock strata, the adjusted principal stress can improve the stability of roadway. The above research results may provide technical basis for the layout and support of mine roadways in the same complicated burial environment.