Evolution law and engineering application on main stress difference for a novel stress relief technology in two ribs on deep coal roadway

Abstract

Routine serried drilling (slotting) technology ruins the coal mass and support architecture of the anchorage ring during stress relief, and cannot resolve the conflict between stress relief and anchorage. Therefore, a novel powerful anchorage and stress relief technology was proposed in this study to balance the conflict. The numerical simulation analysis was conducted on the main stress difference (MSD) of stress relief in large-hole fabrication to acquire the first-best stress relief parameters. 1) When the distance between the starting site of the large-hole fabrication and the roadway wall (L_h), is small, the stress-crest region near the roadway cannot be effectively shifted far from the roadway. When L_h≥12 m, the stress data curve of the roadway rib exhibits a double high crest distribution. When L_h is 10 m, the new crest site of MSD of the roadway rib shifted far from the roadway is 7.5 m without ruining the anchorage function of the superficial part of the anchor cable. 2) The increase in the large-hole fabrication length does not lead to a change in the shape and size of the MSD between the starting site of the large-hole fabrication and the roadway wall. With the increase in the large-hole fabrication length, the migration degree of the crest site of the second MSD is larger than the degree of the crest size of the second MSD. 3) When the large-hole fabrication spacing is >5 m, the high MSD between neighboring large holes appears, resulting in invalid stress relief between neighboring large holes. When the large-hole fabrication spacing is ≤4 m, the small regions of the MSD produced by each large hole are connected, forming a continuous stress relief region in the deep part of the roadway rib. The engineering application results reveal that this powerful anchorage and stress relief technology can effectively control the deformation of the surrounding rock in a deep roadway.

Keywords

deep coal mine / soft coal roadway / large-hole fabrication / main stress difference / novel stress relief technology

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