Research on optimal design of stop line position in working face with rock burst hazard under condition of isolated coal pillar

Abstract

Aiming at the condition of the downhill islanding protection coal pillar in Yaoqiao Coal Mine, the total micro-seismic energy and the frequency continue to rise at the end of the mining face, and the on-site rock burst risk increases. Based on theoretical analysis and numerical simulation, the stress distribution pattern of the coal pillar area in the island and the characteristics of the stress distribution in the coal pillar area before and after the mining of the working face were analyzed. According to the working face mining conditions, the stop line position of working face was optimized. The study shows that the stress distribution characteristics of isolated coal pillar before the mining of the working face are saddle shape. When the mining scale of the working face is greater than 920 m, the supporting stress curve of the coal pillar area gradually changes from saddle shape to a single-peak pattern, and the stress concentration coefficient of the coal pillar area increases from 2.20 to 2.56. Field practice shows that the actual mining scale of the working face is 900 m, which is 30 m ahead of the original design stopping line. The width of the protective coal pillar in the working face section increases from 175 m to 205 m, and the stress in the coal pillar area is saddle-shaped. It effectively ensures the safety of the working face, reduces the stress concentration in the protective coal pillar area of the mining area, and creates favorable conditions for the subsequent mining of the working face.

Keywords

• stress distribution
• isolated coal pillar
• stop line design
• rock burst
• numerical simulation