Study On The Reasonable Sealing Hole Depth Of 2# Coal Seam Drainage Boreholes In Tongshun Mine

Soft coal seam gas discharge is an important means of preventing coal and gas outburst,the sealing technology of mining coal bed is an important part of the gas extraction effect,while the depth of sealing for the gas drainage has a significant influence on quality of sealing. papers to individual coal near the drainage borehole wall there are serious leakage phenomenon in the late at return airway of 02179 mining face as the starting point,on the depth of extraction from the reasonable drilling hole sealing are studied.finally through field industrial test shows that the proposed reasonable hole depth extraction effect is good, the gas concentration is also improved.Through the indoor experiment measured physical and mechanical parameters of the coal seam and roof and floor rock of 02179 working face,for the theoretical calculation and numerical simulation research of thesis provides the basis parameters.using elastic-plastic theory for plastic zone of roadway excavation radius has carried on the theoretical calculation,the result is 4.9m.using the numerical simulation analysis method for the plastic zone along the two sides and the stress distribution due to roadway excavation is calculated,it is concluded that the plastic zone of 0 to 5.6m,0 to 3.40m for the vertical stress area reduction,3.40 to 11.30m for vertical stress concentration region,about 7.0m location reached the peak stress.adopting the method of field test to unloading zones and stress of two clusters of coal roadway excavation were measured,single-hole sonic method to test the pressure relief area is 0 to 3.6m,method of drilling cuttings test pressure relief area is 0 to 3m,the method of drilling cuttings test high stress is 3 to 10m,stress peak position is 6 to 7.5m.in order to achieve good extraction effect, seal ing hole should be more than the depth of the crack of the stress concentration zone,putting forward reasonable hole sealing depth should not be less than 10m.Finally.through the extraction effect of different hole sealing depth validation.it is concluded that the gas extraction from drilling hole sealing depth must be more than stress clusters,and to achieve cost savings,determining the reasonable hole depth is 10m at last.the drilling hole sealing depth ensure the high gas concentration for the borehole of extraction in the later, achieved the purpose of preventing coal and gas outburst and gas utilization.