TWO-STEP GROUTING MODIFIED WATER-PROTECTIVE COAL MINING METHOD FOR ROOF AQUIFERS

摘要

A two-step grouting modified water-protective coal mining method for roof aquifers, comprising a coal seam and an aquifer located above the coal seam, and the specific steps implemented being: acquiring a parameter; obtaining a first spatial range by means of calculation; arranging a plurality of first grouting boreholes; injecting a first grout into a bottom portion of the aquifer, and performing normal extraction; using the parameter to calculate a second spatial range into which a second grout is to be injected; boring out a second grouting borehole; and then injecting a second grout having a high strength and a low permeability. The beneficial effect is: the present method respectively injects grouts of different materials into a roof aquifer before and after mining, in one aspect increasing the thickness of the aquiclude before mining, and weakening disturbances to the roof aquifer from coal seam mining, and in another aspect, also being able to prevent the aquifer and the mining area from being communicated by a water-conducting fracture after mining, thus implementing water-protective coal mining.