Study on mechanism and technology of roof cutting and pressure relief in deep roadway with strong dynamic pressure and high gas

Deep gob-side roadways are subjected to the dual challenges of strong dynamic pressure and high gas content. To address the severe deformation of deep gob-side roadways, the 13131 roadway was used as a case study. Theoretical analysis, numerical simulation, and field testing were employed to study the movement characteristics of overlying strata on the gob side, the deformation mechanism of the surrounding rock, and the technical parameters for roof cutting and pressure relief. The results show that 6.0 m siltstone layer acts as a sub-key layer within the overlying strata. The fracture of arc-shaped triangular blocks triggers the collective movement of thick and hard strata, resulting in increased overburden load, an expanded influence range of side abutment pressure, and severe deformation of the gob-side roadway. The effectiveness of roof cutting and pressure relief depends heavily on the roof cutting height and angle. Effective reduction of roadway deformation is achieved only when the roof cutting height reaches the top of the key stratum; beyond this height, the improvement becomes negligible. At a roof cutting angle of 0°, the transmitted side abutment pressure is minimal. As the roof cutting angle of from 0° to 10°, the deformation of the gob-side roadway shows a slight increase. However, when the angle increases from 10° to 20°, the deformation increases significantly. Based on the key technical parameters of roof cutting and the spatial distribution of gas drainage boreholes, a blasting roof cutting scheme was proposed. This scheme incorporates an advanced safety distance, a protective distance for drainage boreholes, differentiated sealing lengths, and gas monitoring with safety assurance. Field tests demonstrated that this approach effectively controlled roadway deformation while maintaining gas drainage efficiency in roof boreholes.