Mechanism of pressure relief by blasting in the overlying strata of deep coal mine

To effectively reduce the strong mining pressure in deep coal mine excavation, it is proposed in this study to drive a U-shaped roadway in the overlying strata of the coal seam, and effectively release the strong mine pressure through rock blasting. Based on the case of a deep coal mine located in the northwest, two different U-shaped roadway layout schemes are designed for hard rock, the burial depth is −800 m, −825 m and −850 m, −875 m, respectively. The results indicate that blasting in the U-shaped roadway significantly reduces stress and displacement in the working face during the coal mining process. It is shown that the effectiveness of the blasting for pressure relief in the U-shaped roadway is influenced by both relative layer spacing and mechanical behavior of the overlying strata. For the blasted rock strata with similar rock properties, a lower relative spacing between the U-shaped roadway and the coal seam can result in more effective pressure relief.