Roof Water Pre-discharge Feasibility and Standard of Deep Buried Coal Seam Working Face in Mengshan Mining Area

Based on the research of landforms, hydrogeological conditions, roof hole water outflow of working face and goaf water outflow in deep buried coal seam area of Ordos basin, we constructed a working face roof water pre-drainage standard. The results showed that there were three type landforms (i.e. bedrock platform, sand and loess hill). The Quaternary water abundant in sand area was better than that in bedrock platform area and loess hill area, and the Quaternary aquifer was abundant water resource for the first section of Zhiluo formation. All coal mines could be divided three types according to initial water quantity and accumulative amount of water pre-discharge of working face roof borehole. Working face roof borehole outflow was small in Hongqinghe Mine and Weiqiang Mine (q₀≤10.0 m³/h, Q<5.0×104 m³), and the outflow was medium in Hulusu Mine, Bayangaole Mine and Yingpanhao Mine (q₀≤60.0 m³/h, Q=10.0×104 m³ to 100.0×104 m³). In addition, the outflow was large in Menkeqing Mine, Muduchaideng Mine and No.2 Nalinhe Mine(q₀>100.0 m³/h, Q>100.0×104 m³).So we constructed a working face roof water pre-drainage standard. Working face did not need to carry out roof water pre-drainage when q₀=0 to 10.0 m³/h, and water-bearing roof strips (q₀>20 m³/h) should carry out water pre-drainage for the mines with　q₀=0 to 60.0 m³/h. But when q₀>60.0 m³/h, roof water pre drainage had to be carried out for 600 m to 1 000 m working face phased and three months ahead. The final requirements were q₁≤10.0 m³/h and p₁≤1.2 MPa with 90% boreholes.