To investigate the variations in wave velocity fields between impact and outburst coal seams, we analyzed the fluctuations in wave velocity under loading conditions for both coal types. A comprehensive methodology was developed to correct coal wave velocities in response to stress and gas presence, which was then applied to field assessments of hazardous regions. Our findings reveal significant differences in wave velocity alterations between impact and outburst coal seams during loading-induced failure. Gas pressure exhibits a negative correlation with wave velocity in outburst coal (correlation coefficient R² = 0.86), whereas wave velocity in impact coal demonstrates a positive correlation with stress (R² = 0.63). A robust methodology for correcting coal wave velocities in response to stress and gas presence was established to enable more accurate measurement of wave velocity changes. In field applications, seismic wave computed tomography identified stress anomalies that closelycorresponded with geological structures and mining operations, effectively pinpointing hazardous zones. The abnormal wave velocity coefficient ranges for outburst coal seams and impact coal seams are −0.6 to 0.25 and −0.35 to 0.16, respectively, which correspond well with the field stress distribution.

In recent years, tunnel-boring machines (TBMs) have been widely applied in deep coal mining. Turning is an inevitable challenge in TBM tunneling, and a TBM turning roadway exhibits greater instability than a straight roadway, as engineering experience has indicated. This study aimed to explore the failure mechanism and evaluate the support performance of a deep-turning roadway. Several numerical models were established to investigate the deformation of the roadway, the stress distribution, and the failure zone of the surrounding rocks under different tunneling conditions. The results show that the tunneling depth influences the failure pattern of the turning roadway: deep tunneling with high in situ stress can cause asymmetric failure of the turning roadway, while shallow tunneling with low in situ stress does not. Moreover, the change in turning radius, namely the change in roadway geometry, does not influence the stability of the turning roadway. In addition, the support actions for both the straight and turning roadways do not differ significantly, and the amount of controlled deformation of the surrounding rocks is proportional to their natural deformation.

Coal is the main energy source in China. In the process of coal resource mining, the surrounding rock of roadways is often in the complex stress environment of “three heights and one disturbance”. At the same time, rocks in the stratum are often in a three-way unequal pressure state under the action of geological structure, and conventional rock mechanics tests cannot study the mechanical properties of rocks under actual stress conditions; thus, this is based on the self-developed true triaxial multifunctional fluid–structure coupling test system to study the damage mechanical Properties of Sandstone. The results are shown as follows: With an increase in loading rate, the peak damage D_cr of sandstone decreases, but the initial damage D_a increases in the elastic stage, and the brittleness of sandstone weakens. With the increase in the unloading rate, D_cr increases, but D_a decreases in the elastic stage, and the sandstone brittleness increases first, then decreases. In addition, the peak maximum principal strain ε_1maxfirst decreases rapidly and then slowly; the peak minimum principal strain ε_3max increases first, then decreases slowly, and increases slowly; the peak intermediate principal strain ε_2max decreases slowly; and the peak volume strain ε_vmax increases rapidly first and then slowly with increases in the loading rate. With an increase in the unloading rate, ε_1max increases rapidly first, then decreases slowly, then increases rapidly and finally increases slowly; ε_3max first decreases slowly, then increases slowly, and finally decreases slowly; and ε_2max increases slowly then decreases slowly. ε_vmax decreases rapidly first and then increases slowly with increasing loading rate.