Asymmetric deformation mechanism and control technology of roadway under room-pillar group in Huasheng coal mine

The roadway stability of the lower coal seam (LCS) is a huge challenge to mine safety in close-distance coal seams. Herein, the floor stress distribution law of the upper coal seam (UCS) and the layout and control for the roadway in the LCS were studied based on a well-grounded engineering case of the Huasheng coal mine. First, the geological situation, rock mass parameters, and support scheme for the roadway were presented in detail. The asymmetric deformation mechanism of the roadway was discussed based on the data obtained from field observation, and the location of goaf in the UCS was determined using the images captured using borehole optical televiewer. Furthermore, a mechanical calculation model for the room-pillar group floor stress was established, and the floor stress distribution law of the room-pillar group goaf was analyzed using the semi-infinite plane theory. The results indicate that uneven stress under room-pillar group floor resulted in asymmetric deformation, with larger deformation closer to the coal pillar in the LCS. Then, the location and the support scheme for the roadway in the LCS were optimized and verified by numerical analysis and field application. Consequently, the results indicate that the roadway can be relatively well controlled.