Study on Reasonable Coal Pillar Width of Gob-Side Roadway Excavating with Multi-Layer Hard Roof in Western Deep Mine

Gob-side roadway excavating could not only notably reduce the loss of coal resources and improve the coal recovery rates, but also greatly mitigate the imbalance between excavation speed and production needs. However, it is difficult to determine the coal pillar reasonable width of gob-side roadway under the condition of deep buried high stress and multiple key strata superimposed disturbance in the West. With Auxiliary transportation roadway 30207 (ATR 30207) in Muduchaideng Coal Mine as the research background, in situ investigation, theoretical calculation were carried out to study the reasonable width of coal pillar in gob-side roadway under the condition of deep buried high stress multi key seam mining. Results showed that, based on the width of stress reduction zone, two factor control of stress intensity, ratio optimization of width and height and effective anchor width, the optimal width of coal pillar of ATR 30207 is 5.5- 7.7 m. The stability of coal pillar and roadway under different width of coal pillar was simulated and analyzed by using UDEC numerical calculation. The calculation results showed that 6 m width coal pillar was the inflection point of vertical stress, plastic zone and displacement distribution, that is, 6 m width coal pillar was the best width of coal pillar, which verified the theoretical calculation results. This study provides a reference for the scientific mining under the condition of strong mining and high stress mining in Western China.