The underground rock was disturbed repeatedly during the excavation, resulting in its damage degree gradually accumulated. Therefore, the rock in practical engineering can be regarded as predamaged (PD) rock, and its mechanical behaviors are different from conventional intact rock. This paper proposed the calibrate method to evaluate the predamaged degree of rock based on acoustic emission (AE) ring counts, and the PD rock samples were prepared by uniaxial cyclic loading and unloading test. Then, the triaxial compression experiment of predamaged rock was carried out to study the influence of different predamaged degrees on mechanical behaviors and damage evolution characteristics. The results show that the peak stress and axial strain of PD rock decrease gradually with the increase of predamaged degree. The yield stage of PD rock was significantly shorter than that of intact rock, and it entered the dilation deformation earlier. Furthermore, the constitutive equation of the PD rock based on energy was constructed and the damage evolution characteristics of PD rock were analyzed. It was observed that the bigger the predamaged degree was, the earlier the rock entered the damage, and the failure mode was more complex and crushed. The research results can provide the theoretical basis for the stability control of engineering disturbed rock.

Fault structures can cause a bad mining environment and increase the stress of surrounding coal pillar faults. The study investigates the stress evolution characteristics within fault structure groups and their surrounding coal pillars and explores the extent to which these fault structure groups influence the stress distribution in coal pillars. Based on three-dimensional modeling technology, a transparent geological model of the geological environment of fault structure groups was constructed and finite difference software was used to generate a numerical simulation model. Two survey lines and four survey points were arranged to analyze the stress distribution of a coal pillar fault. The results show that the fault structure groups have obvious stress barrier effects. There is a 35 m stress reduction zone in the hanging wall of the fault and a 30 m stress increase zone in the footwall of the fault. Both FL-1 and FL-3 faults have a stress barrier effect in the hanging wall. The obvious stress increases in the footwall of the fault are 37.7 MPa and 33.5 MPa, respectively. The stress of the FL-2 fault as a whole appears to be a more obvious superposition at the end of mining, and the peak stress reaches 41.5 MPa.

This paper studies the distribution characteristics of acoustic emission (AE) events in supporting roadways under different dynamic load conditions through numerical simulation and theoretical analysis. According to the principle of AE numerical simulation, the roadway model is established by FLAC3D software, and the supporting structure of the bolt cable is established by editing the Fish function. According to the model dynamic load application criterion, the relationship between the peak velocity of the particle, the distance from the source center to the dynamic impact damage point, and the dynamic load intensity is introduced. The velocity-distance-energy relationship is deduced from the relationship to determine the magnitude of the dynamic load energy. The simulation results show that the intensity of the dynamic load source and the distance of the dynamic load source directly impact the AE events. The larger the dynamic load intensity and the closer to the dynamic load source, the more concentrated the AE events. The roadway has a blocking effect on the transmission of the dynamic load stress waves. According to this characteristic, the roadway can be protected by a high-pressure relief roadway. Rock lithology greatly influences the transmission of dynamic load stress waves and the number of AE events. When the dynamic load stress wave passes through the rock strata of different lithologies, the attenuation of the dynamic load energy and the number of AE events are large. However, when the dynamic load stress wave passes through the rock strata of the same lithology, the attenuation of the dynamic load energy and AE events is small. The surrounding rock structure in the bottom corner area of the roadway is susceptible to disturbance from dynamic load sources above the roadway. The results are greatly significant for studying the AE characteristics of support roadways with disturbance-typeimpact failure.