Study And Application Of Transformational Hydraulic Punching

The technique of mining conditions without protective layer of coal and gas outburst prevention by hydraulic punching was studied in detail in this paper.The principle of the technology, mechanism of action and effects were investigated with the method of theoretical analysis, laboratory experiments combining with field trials based on in-depth understanding of the progress in related areas of the research, then significant technical and economic benefits were received.Punching and damage model were established and researched according to the way of the coal-water impact in this paper, then crushing type of coal when punching was talked—the destruction of coal by water jet was the effect of shear and tension. Coal fracture pressure threshold under the situation of coal-breaking was obtained by mechanism of coal combined with the methods of statistical damage used uniaxial and triaxial coal compression test data to calculate the value to compare and optimize with actual production, then the main factors affected the punching effects was analysised according to the application. The flow characteristics of impingement area in the system was researched by boundary layer theory and the calculated maximum flow rate was 59m/s; The stress wave theory was introducted and the maximum depth (3.0m of B11b and 4.0m of B9b) of punching was received according to the characteristics of high velocity of punching,. The punching equipment (emulsion pump and rig) was selected according to actual parameters of Lizuizi coal seam and the technical parameters of punching were studied. The results showed that the relationship between coal quantity and water pressure was not simply a positive correlation, the speed of coal out of lanes and punching pressure was a positive correlation, and the rate of coal out of the drilling remained the same when the pressure increased to a certain value. The mine optimal punching pressure was 10～14MPa. The total amount of coal increases with effective punching the time to keep increasing the general trend. Moreover, the minimum pump pressure of the two coal (13.7MPa and 11MPa) when hydraulic punching was obtained under optimization of structural parameters on the nozzle combined with pipe pressure loss by calculation.Punching operation safety precautions and gas ventilation management measures were set down under production conditions, which can provide security technical support for the punching operation. A detailed study on the basis of gas parameters and index of pressure relief as well as increased-permeability before and after punching were researched in Li Zuizi coal mine.Figure [24] table [18] reference [89]...