Study on Reasonable Coal Pillar Width and Supporting Technology of Gob-Side Entry in Kilometer Deep Mine

Aiming at the large deformation issues related to the gob-side entry in Zhujixi kilometer deep mine, the instability and destruction characteristics of deep mine roadway were analyzed, theoretical calculation and numerical simulation methods are used to determine the reasonable coal pillar width of the 11502 haulage gateway. Based on the underground test, the measures of surrounding rock deformation control are proposed, then finally formed a high prestress and stable bolting with wire mesh supporting scheme. The research result indicates that with the coal pillar width increases, the range of the stable bearing area in the middle of the coal pillar gradually expanded during the driving, during normal mining period, the roof subsidence and integrated coal beside displacement decreased, but the floor distending increased, Therefore, it is considered that 8m wide coal pillars can ensure the reliable anchoring of the bolt. Increasing the initial tightening torque of the bolt and carrying out the second tightening can give full play the bolt supporting property, and the over-tension of the anchor cable can quickly achieve high-resistance support. The umbrella-shaped shrapnel device can ensure the anchoring reliability of bolt, in addition, the anti-skid self-locking device can reduce the possibility of the slip of the anchorage and the ejection of the broken strand effectively. The underground test shows that reasonable coal pillar width with strength bolts and cables combined with high pretension can effectively control the deformation of surrounding rock along gob-side entry and ensure the normal service ability of roadways.