Application of Strip-Partial Mining to Prevent Water Inrush from Coalbed Floor in Nanding Coal Mine

For exploiting safely in deep area where the coalbed were threatened by confined aquifer under coalbed floor of Nanding coal mine in Shandong province of China, this paper has put forward the strip-partial mining method and have calculated the mining width and coal pillar width based on the allowable distortion of the earth´s surface and prevent water inrush from coalbed floor. First, this paper put forward the strippartial mining method because the mining width of workface was the main factor affect permeable failure depth in the coalbed floor. Second, according to the formula of permeable failure depth in the coalbed floor and safe aquifuge thickness with formula in Rule, the paper calculated the mining width in different depth based on the thickness of aquifuge, safe aquifuge thickness, permeable failure depth in the coalbed floor, the allowable distortion of the earth´s surface and damage of rockmass. Last, the coal pillar width was calculated by the actual load and limit load where the safe factor was 1.2 under the conditions of different mining width and different depth. The result was validated by the actual, the mining width and coal pillar width accorded with Nanding coal mine fact. The result of prediction will guide Nanding coal mine exploit safely in deep area.