Experimental study on the mechanism of pressure releasing control in deep coal mine roadways located in faulted zone

The existence of faults is easy to cause large rock deformation, rock bursts, coal bumps, and other accidents in highly stressed deep coal mines. Based on a roadway accident occurred in the deep Xinjulong Coal Mine located in a faulted zone in China, we explore the law of mining pressure at the working face and in the roadway and analyze the root cause of the accident. We then propose the roof cutting and pressure releasing method using directional pre-splitting for deep roadways in faulted zone. Furthermore, we develop a physical model testing system and then conduct tests to investigate the pressure releasing mechanism. Subsequently, the decreased law of surrounding rock stress under different roof cutting parameters is obtained, which verifies the advantages of the roof directional pre-splitting. Moreover, we establish the optimization method for pressure releasing design parameters for this type of roadway and examine the control mechanism of roof cutting and pressure releasing. The test results show that stress concentration appears in the surrounding rock of the roadway without roof cutting with a maximum stress of 4.82 times the original rock stress and located close to the roadway surface. After the roadway is depressurized by roof cutting, the stress concentration can be reduced by 91.5%, and the peak stress position is shifted significantly away from the roadway. Finally, we provide some engineering recommendations for deep roadways in faulted area and the results of this study can also provide guidance for the safety control of deep roadways under similar conditions.