Study on narrow coal pillar width and surrounding rock control technology of gob-side entry driving with soft and broken composite roof

Abstract

In order to solve the problem of determining the width of coal pillar and surrounding rock control in gob-side entry driving with soft and broken composite roof, in view of the deformation and damage characteristics of soft and broken composite roof in gob-side entry driving of 21210 working face of a mine, the width of narrow coal pillar is comprehensively determined to be 7 m by means of theoretical analysis, numerical simulation and engineering practice, and the corresponding surrounding rock control countermeasures and technologies are proposed. The results show that: the width of the internal stress field is 11.8 m, the failure width of the coal pillar near the goaf side and the roadway side is 2.5 m and 1.8 m respectively, and the reasonable width range of the narrow coal pillar is 5.6-7.3 m; when the coal pillar size is 7-11 m, the plastic zone of the surrounding rock of the roadway roof decreases, and the range of the elastic core zone expands, which is conducive to the anchoring of the anchor cable in the composite roof; 7 m coal pillar and the combined support technology of “high-strength bolt (cable) channel steel truss mesh + roof grouting” can effectively control the surrounding rock in gob-side entry driving with soft and broken composite roof.

Keywords

• composite roof
• gob-side entry driving
• narrow coal pillar
• grouting reinforcement
• combined support