Study On "Two Sealing And One Grouting" Drilling Hole Sealing Technology Parameters

Extraction from the gas drilling is an important means of management of coal mine gas in our country,but the quality of the drilling hole sealing is often difficult to achieve the ideal effect,which restricts the gas extraction effect,and leads to low concentration of the gas extraction and shorter effective extraction time.Therefore "two sealing and one grouting" device is put forward,and the hole sealing parameters are studied.First of all,the mechanism of gas extraction from drilling hole sealing is explored.And the coal mine drilling surrounding rock stress distribution has been carried on the theoretical analysis and numerical simulation,and the results show that when the drilling hole sealing section stress clusters or the original stress zone in surrounding rock hole sealing effect is good,and when the grout is diffused into the broken zone and plastic zone,the sealing could be improved.Secondly,combining with theoretical analysis,using the numerical simulation software FLAC3D to explore the best sealing hole depth of bedding drilling and wear layer drilling,the simulation results show that the best depth of No.8 coal seam bedding drilling hole is 10?30 m from the wall,and the best depth of No.10 coal wear layer drilling hole is 10?18 m from roof of the tunnel bottom.The simulation results of COMSOL software show that appropriate increase of grouting pressure can increase grout diffusion radius,and enhance the sealing.Finally,the hole sealing device is tested and applied in Pingdingshan No.8 and No.10,and the best depth of bedding drilling and wear layer drilling hole sealing are verified.Experimental results show that this kind of hole sealing device can obtain better hole sealing effect than traditional hole sealing device.