Yili District of Xinjiang is rich in coal and water and has become one of seven coal chemical industry bases in China.Yili mining area is the only oasis mining area of five large-scale coal mining bases in Xinjiang.Aquifer-protection in coal mining is the most difficult problem which needs to be solved for economic development in Yili district.Based on the situation of extremely thick coal seam at Yili mining area,the features of structure and mechanics of overlying coal seam were analysed.Numerical models were adopted to study the rupture rule of overlying rock,the development of mining fissure,and coupling relationship between the structure of key stratum and impermeable layer.The results show that the area nearby the cut-open and deadline is likely to become new fractures for water flowing when upper layer strata mining.The key layer guarantees the stability for aquifuge which suppresses and weakens the role of the internal fractures overlying key layer strata with the lower layer mining,new fractures zone ranges from50 to 150 m next to the open-cut and within the scope of 25 m near by the stop line.Thus,the stability of surrounding rock nearby the fractured zone plays an irreplaceable role in water-preserved mining.
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