Confirmation of topsoil stripping sequence of time and space based on grid method

Underground coal mining caused severe impact on the land surface,especially in the area with high groundwater level,the mining subsidence due to the water logging,without timely protection measures,the massive precious topsoil will be lost.The beforehand topsoil stripping of the future water logging area is an effective way to save the topsoil.By application of the grid method,the waterlogging grid units in the study area have been obtained,based on the land surface gridding and the land subsidence prediction in the 5simulative work faces;to find out the impact area of the coal seam by the projection of the waterlogging units with the coal seam impact area angleθ;taking the water grid unit G(5,7) and G(5,8) as an example,to determine the first prediction unit according to the impact area of the coal seam,and predict the subsidence by stage,to calculate the mining progress of the work face when the two grids arrive the waterlogging criticality;therefore,the water logging order of the two units could be obtained.The results could be a reference to the rational conduction of the land reclamation mechanical construction,and enhance the efficiency.