Mechanical Mechanism Of Drilling Rod Sticking In Outburst Soft Coal Seam

Many of China’s coal mines are high gas mine and outburst mine, and the coal seams are low permeability seams, coal and gas outburst disaster is very serious, so the "double four in one" comprehensive prevention outburst measures are significant for preventing and treating the coal seam gas disaster. Because the outstanding seam is often the soft coal seam, and the destruction of the extraction drill, prediction and effects test hole often occurs drill pipe sticking phenomenon, results in low drilling depth and the hole forming rate is low, the implementation of the measures are not in place, the prediction and the test results are not accurate,influence the safe and efficient production of coal mine. To solve the above problem, we need to study the drill sticking mechanism and propose solutions.This paper directs pipe sticking phenomenon which often takes place among soft coal seam drilling process. The first, based on the mechanical mechanism, we analyzed the motion law of the drilling cutting in the helical blade of the auger drilling rod and the circular pipe during the drilling, at the same time, use the rock mechanics theory analysis stress distribution and damage zone radius around the drill, and use the RFPA numerical simulation software to simulate the drilling failure area, combine the theoretical analysis results to determine the damage zone and borehole deformation, to determine the drilling production process of pulverized coal. For the Hebi No.6 Coal Mine, the pulverized coal production capacity of 42 mm drilling is 3.32 times that of the ideal state, the pulverized coal production capacity of 75 mm drilling is 3.11 times that of the ideal state, the pulverized coal production capacity of 113 mm drilling is 2.13 times that of the ideal state. From the point of control the drilling speed to eliminate or reduce the occurrence of the phenomenon of sticking. After the engineering application in 2123 working face and 2145 working face of Hebi No.6 Coal Mine, it confirming the method is effective and feasible, and it has important theoretical and practical significance.The results show that: soft and outburst coal seam occurs pipe sticking phenomenon is due to that the drilling speed is too fast, lead to the output coal is greaterthan the discharge capacity of the drill pipe. So control the drilling speed, reduce the production, discharge the pulverized coal in the borehole in time, can greatly reduce the sticking probability. In the course of engineering applications, after control the drilling speed, the drilling depth doubled, the hole success rate is greatly improved,it can achieve the purpose of efficient drilling.