STUDY ON FORECASTING ROCKBURST OF THE DRILL PIPE TORQUE METHOD

The drill pipe torque method is a method that judges rock burst risk in coal mine by testing the magnitude of the drill pipe output torque given by the rig in the drilling process, and it possesses irreplaceable advantages compared with many traditional methods and is a potential prediction method. A mechanical model for the drill pipe is established in a drill cuttings process, the relations among the drill pipe torque and the coal stress, coal properties and drilling speed are obtained, and the analysis indicates that: in a drilling process, when the coal stress increases the drill pipe torque also increases, but the drilling propulsion decreases; when the drilling forward speed increases, the drill pipe torque and the drilling propulsion also increase; when the coal strength increases the drill pipe torque and the drilling propulsion increase as well. Testing the variation of the drill cuttings torque under different coal stresses by using the drill pipe torque device, it shows that if using the same rig and drilling tools and chiseling the seam of identical property at the specified speed, the drill pipe torque increases with the coal stress, and there is better consistency between the drill pipe torque variation and the coal stress and the drilling bits. The coal stress field is obtained near the drilling by testing the drill pipe torque variation, the rock burst risk is forecasted further. The study provides a certain theoretical and experimental basis for the prediction of mine dynamic disaster.