Determination of coal pillar width for gob-side entry driving in isolated coal face and its control in deep soft-broken coal seam: A case study

Large deformation control of surrounding rock in deep soft-broken coal roadway has always been a key scientific and technological problem restricting the deep coal resources exploitation. Taking the gob-side entry driving (GED) in isolated coal face under deep soft-broken coal as research object, the prominent difficulties of surrounding rock control were clarified. Through numerical simulation, the evolution laws of deviatoric stress and plastic zone of GED under different coal pillar widths were studied. Combined with rational calculation, reasonable coal pillar width was determined to be 7.0 m. The study shows that severe disturbance distance in the front section of the coal face is 22 m, and makes it clear that coal pillar and roof are the key control areas. A subregional asymmetric combined support technology named anchor cable truss in roof and coal pillar + anchor cable in solid coal + single prop reinforced support in 25 m ahead of the coal face was proposed. The field application and ground pressure observation results show that good control effect has been achieved after adopting subregional asymmetric support technology under 7 m coal pillar width. The research results have important reference significance for safe mining in deep coal resources.

Automated summary

The large deformation control of surrounding rock in deep soft-broken coal roadway has long been a challenging issue for the exploitation of deep coal resources. By studying the gob-side entry driving in isolated coal face under deep soft-broken coal, a reasonable coal pillar width of 7.0m was determined, and a subregional asymmetric combined support technology was proposed with good control effect observed in field applications under this width. This research has important reference significance for safe mining in deep coal resources.