Segmented enlarged‐diameter borehole destressing mechanism and its influence on anchorage support system

Abstract

AbstractLarge‐diameter borehole destressing technology is one of the main technical measures for the prevention and control of coal mine rock burst. In engineering practice, there is generally a contradicting problem due to the presence of excess destressing which damages support system and insufficient destressing which results in high stress hardly transfer. In this paper, the mechanism of large‐diameter borehole destressing technology and its influence on anchorage support were simulated and analyzed. Based on this, a segmented enlarged‐diameter borehole destressing technology was proposed. The destressing effect at deep part and anchorage strength changing at shallow part of the coal rib were studied under different borehole parameters. Numerical simulation results show that the destressing effect increases with the increase of the borehole diameter, while borehole with oversize diameter increases the deformation of the roadway and weakens the strength of the anchorage support. The diameter‐enlarging point in segmented enlarged‐diameter borehole destressing technology is best placed between the anchorage end and the vertical stress peak point. The anchorage strength is inversely correlated with the diameter of the small‐diameter section, and the destressing effect is positively correlated with the diameter of the large‐diameter section. Based on its advantages in destressing, the segmented enlarged‐diameter boreholes and anchorage support are applied together, and a system of destressing‐support cooperative control of rock burst is presented. The roles in rock burst control of "zone of strong anchorage support" and "zone of low stress and energy dissipation" are described.