Study On The Technology Of Filling And Plugging Air Leakage At The End Of Fully Mechanized Caving Face In Dananhu No.1 Mine

Leakage in goaf is one of the important causes of mine fires.On the one hand,the top coal caving rate is limited by many aspects,and the amount of coal left in the goaf is large;on the other hand,the end of the fully mechanized caving face is generally less coal or even coal,resulting in insufficient roof collapse.The open space is large.Therefore,the end of the fully mechanized caving face is prone to form a wind leakage passage,and there is a potential risk of spontaneous combustion of the coal in the goaf.In this paper,theoretical analysis,laboratory experiments,numerical simulations and field tests are used to study the technology of the end-filling and plugging of the fully mechanized caving face with the Dananhu No.1 Mine as the engineering background.The main research results are as follows:(1)The mechanism of air leakage at the end of the fully mechanized caving face was analyzed.Combined with the on-site measurement of the ventilation parameters of the working face,the FLUENT numerical simulation software was used to analyze the characteristics of the wind field in the goaf of the fully mechanized caving face,which confirmed that the end of the working face is the main channel for the air leakage in the goaf,and also caused the gas in the goaf to the working face.One of the main exits of the escape.The wind speed decreases sharply at the right angle turn of the air inlet and the working face,and then a relatively low pressure area is formed,which causes the carbon monoxide,gas and other gases in the working face and the goaf to gather toward the corner under the pressure difference.After the tip is filled,the air leakage condition is improved and the accumulation of gas in the goaf to the working surface is effectively prevented.(2)The experimental study on the proportion of foamed fly ash end filling materials was carried out.Through the single factor analysis test and orthogonal test,the effects of various components of foamed fly ash filling materials on the mechanical properties of the filling materials were studied.The conclusions were as follows: the incorporation of foam greatly reduced the uniaxial compressive strength of the filling materials.Strength,the filling material has high residual strength and strong ductility after being mixed into the foam;as the cement content increases,the peak strength of the filling material increases continuously,and the cement property dominates the mechanical properties of the filling material,and the filling material.The peak intensity of the sample at 7 and 28 days did not change much,and showed high residual strength and strong ductility after the failure.Based on the demand for material properties of the on-site plugging wind,a suitable ratio of fly ash filling materials was selected.(3)The end-filling system of the fully mechanized caving face was designed.Combined with the engineering characteristics of the end-filling of the fully mechanized caving face,the downhole mobile filling system including material storage and mixing,duct foaming and pipeline transportation and the equipment arrangement in the filling preparation chamber are designed;combined with foam fly ash filling The work performance of the material,the design of the working surface end of the balloon type filling template and construction process.(4)A plan for filling and sealing air leakage at the end of the 1305 fully mechanized caving face of the Dananhu Mine was established.Combined with the filling requirements of the end of the 1305 fully mechanized caving face,the layout position of the underground filling system and the airbag filling construction method of the working face end were designed.The working flow rate of the filling slurry and the filling pipe diameter and filling parameters were determined.Filling equipment for matching selection.The gas concentration monitoring of the working face and the gas concentration monitoring program of the goaf were designed to test the effect of filling and sealing air leakage.Fly ash is recycled to the well and used to protect the environment.It provides a way to solve the spontaneous combustion disaster in coal mine goaf and is an important measure for green mining of coal resources.