In situ groundwater protection technology based on mining⁃conservation coordination in the middle and upper reaches of Yellow River Basin

Coal mining is the most intensive human activity that causes the damage of surface ecological environment in the coal mining area of the Yellow River Basin，and the contradiction between supply and demand of water resources is the key factor limiting the ecological environment governance and green mine construction in the coal mining area. In order to alleviate the impact of coal mining on groundwater resources and surface ecological environment，based on the damage mechanism of aquifer under the influence of mining， the groundwater protection idea of coal mining near the Yellow River Basin was formed. Also the in situ groundwater protection technology of coal water coordinated mining in the middle and upper reaches of the Yellow River Basin was proposed. Its basic principle was ex⁃ pounded，i.e. controlling the hard roof not to break and replacing the coal pillar with backfilling body. Two technical steps(strip mining of reinforced coal pillar and backfill mining with retaining narrow coal pillar) and their advantages were introduced. Combined with the surrounding rock control technology of gob side entry retaining and the rapid re⁃ sistance increasing strength of backfill mining， the feasibility of two technical steps was analyzed by establishing the hard roof fracture mechanical model. Taking the Shuangliu coalmine near the Yellow River Basin as the research object， the key technical parameters were analyzed and determined， such as the strip mining parameters，the backfill width beside the coal pillar，the reserved width of the narrow coal pillar，and the minimum backfill rate of the hard roof without breaking. Meanwhile， based on the strip mining pillar stripping theory and long⁃term stability evaluation method，it is concluded that the coal pillar and backfill body retained in this technolo⁃ gy have long⁃term stability，which can effectively protect the aquifer and surface ecological environment.