Plugging factor and new plugging method to hydraulic relieving stress

The phenomenon of blocking hole and drill holding often occurs when using water jet cutting,and hydraulic punching to enhance the gas drainage in soft coal seams. To solve such problems,a device and an integrated method for breaking coal,dredging and slagging are developed in this paper. Through controlling the direction of water with water pressure,the high pressure water is used to break coal and relief pressure or dredge slag. Based on the analysis of the causes of plugging holes,according to the continuous medium model,the force of the drill pipe was analyzed and the mechanics mechanism of holding and drilling were investigated. The relationship between the torque of drilling rig and the length of the hole and the parameters of the hole is obtained. Based on the analysis of the water jet drilling,the critical parameters of jet dredging slag were studied,and the critical nozzle installation position of dredging was ob- tained. In addition,a coal breaking,dredging and discharging device and its integration process were developed. Ac- cording to the field test,the new method can effectively eliminate the hydraulic pressure relief in the process of the e- mergence of plugging hole,and holding drill.