doi:10.16186/j.cnki.1673-9787.2023030035

Received:2023/03/15

Revised:2023/05/13

Published:2024/05/15

Numerical simulation study on optimal parameters for borehole destressing in the sidewalls of excavation roadways in extra-thick coal seams

ZHAI Xinxian1, REN Zhu’an1, FANG Jianchang2, LU Defang2, ZHAO Xiaofan1, GUO Zhaoyang1

1. School of Energy Science and Engineering， Henan Polytechnic University， Jiaozuo  454000， Henan， China; 2. Qianqiu Coal Mine， Henan Dayou Energy Co.， Ltd.， Sanmenxia  472300， Henan， China

Abstract: Currently, borehole destressing technology is one of the main measures to prevent coal bumps during roadway excavation in coal mines. Objectives The layout and parameters of boreholes are critical to the effectiveness of destressing. Methods This study uses numerical simulations based on the geological and mining conditions of the fully mechanized caving face at Gengcun Coal Mine. It examines the stress distribution in the surrounding rock of excavation roadways, specifically the vertical stress distribution along the two ribs of the roadway, by analyzing different borehole configurations. These configurations include single-row boreholes with varying depths, diameters, and spacing, and double-row boreholes with varied row spacing. Results The findings are as follows: (1) With a single-row borehole arrangement, as borehole depth and diameter increase, high-stress zones on the two ribs of the roadway gradually shift toward deeper surrounding rock, while the shallow surrounding rock remains in a low-stress zone. (2) When the borehole depth and diameter reach a certain threshold, the abutment pressure curve along the two ribs transitions from a single-peak to a double-peak distribution, indicating a critical destressing state in the shallow surrounding rock. Further increases in borehole depth and diameter lead to an excessive destressing state along the two ribs. (3) The degree of stress transfer ∆L of the high- stress zone to deeper surrounding rock and the ratio η of the distance between the peak stress points and the roadway surface, with and without borehole destressing, serve as quantitative indicators of the critical and excessive destressing states, allowing for optimal borehole parameters to be established. The implementation of advanced borehole destressing, combined with secondary support—using bolts, cable anchors, and 36U-type retractable metal supports—at roadway 13230 in the Gengcun Coal Mine has shown significant destressing and anti-impact effects along the two ribs of the roadway. Conclusions These findings provide practical guidance and reference for preventing coal bumps during roadway excavation in coal mines.

Key words:extra-thick coal seam; extraction roadway; borehole destressing; abutment pressure; borehole parameters