Aiming at the potential risk of water permeability induced by the expansion of overlying rock cracks after coal seam mining in Changjiagou Reservoir near the water body of Zhangjiaomao,model tests and numerical simulations were conducted on the overlying rock damage characteristics and crack expansion rules during coal seam mining.In order to reasonably determine the width of the water-proof coal pillar in the 4-2 coal seam,based on the different mechanisms of mine support pressure and static water pressure on the water-proof coal pillar,the water-proof coal pillar in the 4-2 coal seam was divid-ed into pressure affected zone and effective water-proof zone.The force analysis and calculation models of the coal pillar in the pressure affected zone and effective water-proof zone were constructed,and the theoretical width calculation formulas for the pressure affected zone and effective water-proof zone in the 4-2coal seam were derived.On this basis,considering the relationship between the boundary angle of coal seam mining and the width of different coal seam pressure influence zones under the water body,a method for determining the width of water-proof coal pillars in the coal seam group under the water body was proposed,which includes the width of overlying coal pillars and the pressure influence zone.The results show that the initial pressure step distance of the 4-2coal seam working face is 45～56 m,the periodic pressure step distance is 13.8～14.9 m,and the height of the overlying rock caving zone is 12～13 m.The maximum surface subsidence is 2.0～2.2 m,with a subsidence coefficient of 0.571～0.629.The reasonable widths of the water-proof coal pillars for coal seams 4-2,4-3,4-4,and 5-2 are 25,39,51 and 87 m,respectively.The on-site measurement of the water blocking effect has ver-ified the rationality and engineering applicability of the theoretical reserved width of coal pillars near the water body,providing technical support for the safe and efficient mining of coal seams near the wa-ter body in Zhangjiamao.
关键词
近水体煤层群/覆岩破坏/隔水煤柱/矿压影响区/有效隔水区/合理宽度
Key words
near water seam group/overlying rock failure/water-proof coal pillar/mine pressure affect-ed area/effective water-proof area/reasonable width
维普
万方数据