Exploration On The Cooperative Prevention And Control Of Gas By "Air Exhaust" And "Drainage" In W4301 Working Face Of Gaohe Energy

With the increase of coal mining depth,the amount of gas emission in working face is getting larger and larger,especially the uneven gas emission during comprehensive mechanized top coal mining,which makes the working face,especially the upper corner gas,frequently exceed the limit.At present,there are mainly two ways to control the gas in the working face: "air exhaust" and "drainage".Among them,"air exhaust" gas control is the most direct,economical,and reliable method.By changing the roadway layout of the working face and increasing the air distribution of the working face,the "air exhaust" gas amount of the working face is increased.Due to the limitation of the limit air volume at the working face,it is difficult to dilute all the gas flowing into the working face to a safe concentration;the “drainage” method is used to pump the gas that has not been released into the wind flow in advance,which can effectively solve the problem of gas overrun at the working face.However,the gas drainage works are large in volume,time-consuming,and costly,and the roadway system of the working face needs to be completed in advance,which adds pressure to the mining connection of the working face.Therefore,after the gas drainage design of the working face is made,the effect of the "drainage" of the working face gas must be inspected to ensure that the remaining gas in the working face can be diluted by the wind after it is put into production.Considering the time and cost issues of "air exhaust" and "drainage" gas,the search for a method of "air exhaust" and "drainage" synergistic treatment of gas in working faces has become a real problem that high-gas mines need to urgently solve.Gaohe Energy is a typical high-gas mine.Its coal seam is deeply buried,gas permeability is poor,and gas emission from fully mechanized caving mining is large and uneven,making gas control difficult.In response to this problem,this paper takes the W4301 face as the research object,on the basis of analyzing the actual situation of the face and the root cause of gas emission,proposes the use of "wind exhaust" and "drainage" to prevent and control gas in the face and conduct feasibility exploration,To provide theoretical guidance for gas control in high-gas coal seam mining in Gaohe Energy.This article uses a combination of theoretical analysis,numerical simulation and on-site measurement research methods.The main research contents are as follows:(1)According to the classic rock pressure theory and "O" ring theory,combined with the lithology characteristics of the overburden layer in the 3 # coal seam of Gaohe Energy Source,the failure characteristics and crack evolution law of the overburden in the goaf under fully mechanized caving conditions are analyzed,and Using theoretical calculation,numerical simulation and detection analysis of water injection in the uphole,the development height range of the "three vertical zone" cracks in the gob of the W4301 working face was obtained,and the relevant parameters of the "three horizontal zone" of the goaf were calculated by introducing the fracture and expansion coefficient of coal and rock masses,Which provides parameter basis for the following research.(2)Based on the three laws of ventilation,construct a mine threedimensional ventilation network solution model,and combine the parameters of on-site resistance measurement to adopt the "two-entry two-return" type,"threeentry one-return" type and "two Three types of ventilation systems of "one return" type are used for air volume distribution and air flow simulation,and the ventilation lines of each ventilation system and the air volume values of each roadway are determined,so as to provide air flow parameters for later research.(3)Through the Fluent simulation test face,the gas migration law and the effect of air exhaust gas treatment under three different ventilation systems.The analysis found that the gas concentration at the upper corner of the test face was 1.35 % after adopting the "two-entry and two-return" type ventilation system,far exceeding the limit value of 1 % specified in the regulations;the "three-entry and one-return" type and After the "two-in-one-out" type ventilation system,the gas concentration in the upper corner has decreased,being 0.91 % and 0.86 %,respectively.The gas concentration in the return air channel is 1.15 % and 1.52 % respectively,both exceeding the stipulated value of the regulations,and there are high-concentration gas clouds in the mined-out area,which has greater hidden dangers.Therefore,it is impossible to eliminate the gas emission from the working face only by the action of air exhaust,and it is necessary to further combine the drainage measures to strengthen the gas control.(4)Comparison of the gas concentration distribution in the mined-out area after the joint arrangement of three different ventilation systems and highdrainage roadways in the test face.The analysis found that under the synergy of air drainage and extraction,the corners and roadways on the face The internal gas concentration meets the requirements of the regulations.Among them,the gas concentration at the corner of the working face is 0.53 % under the joint arrangement of the "two-inlet and one-return" ventilation system and the highdrainage lanes,which is lower than that of the other two ventilation systems,and the "two-inlet and one-return" ventilation system The small amount of roadway excavation works and the short construction period can alleviate the restriction of roadway excavation on the production of the mining face.Comprehensive consideration,it is more reasonable for the W4301 working face to adopt a "two-in,one-return" type ventilation system and a high-drawing road.(5)Through on-site industrial tests on the W4301 working face of Gaohe Energy,the influencing factors,emission rules and gas control effect of the working face were analyzed.The on-site comparative analysis shows that the gas control effect is significant after the combined arrangement of "two-in-oneout" ventilation system and high-drainage roadway.The gas concentration in the working face is about 0.65 %,the upper corner(0.55～0.67 %)and the remaining roadway(0.33～0.85 %)are all below 1 %,which has achieved good safety production effect,and also provided a reference for gas control of high gas coal seam mining in Gaohe Energy.