Rockburst Risk Assessment And Prevention Of 5301(South)Working Face In Jisan Coal Mine

Rockburst is the most typical dynamic disaster in many disasters of coal mine.Its essence is the sudden instability and failure of coal rock under the action of high stress.When rockburst occurs,it is usually accompanied by coal rock throw out and violent vibration,which is very easy to cause safety accidents.However,the underground environment is complex and the geological conditions are changeable,which leads to the occurrence of rockburst events with no regularity and strong unpredictability,and the failure forms and treatment measures of rockburst events caused by different reasons are quite different.Therefore,it is necessary to conduct in-depth study on the rockburst problem of the coal face underground.For this reason,in view of the difficult problem of the risk assessment of rockburst in the 5301(South)working face of Jisan coal mine,the paper analyzes the influence rules of various geological and engineering factors on the risk of rockburst by using the methods of theoretical analysis,laboratory test and engineering practice,studies the mechanism of rockburst during the mining process,and puts forward the targeted measures of pressure relief and outburst relief.The main achievements are as follows:(1)5301(South)working face is in the "isolated island" state,and the width of the working face presents a "wide narrow wide" change,which becomes a difficult problem in the evaluation and prevention of rockburst.The "isolated island" state of the working face makes the unsymmetrical overlying rock structure on both sides act on the coal seam.The "equivalent mining depth" should reflect the real stress state of the coal seam,and the "equivalent mining depth" of the working face is 986 m,which is the real one The inter stress value should be 1.86 times of the vertical stress.(2)According to the actual conditions of the working face 5301(South),the comprehensive index method is used to analyze the geological factors,mining technical conditions and other factors in the whole range of the working face.The possibility index method is used to quantify the nature and internal stress state of the coal and rock mass,and it is concluded that the conditions for the occurrence of rockburst are available in the whole range of the working face.(3)The occurrence mechanism of rockburst and the division of dangerous area are studied.The low roof and high roof of the working face move asynchronously and interact with each other,and the location of rockburst is complex and changeable;"island" working face is the "key working face" of dynamic disaster,which plays a leading role in the movement of key rock strata.When it is pushed to the "square" and other key positions,the bearing characteristics of the overburden structure changes,resulting in a sharp increase of the working face’s rock pressure,which is impact The important opportunity and location of increasing the risk of ground pressure;when the working face is pushed to the vicinity of the fault,the mining stress and structural stress are superposed,and the coal and rock mass enter the state of high stress,which is prone to impact ground pressure events.(4)According to the law of stress distribution,the mining area can be divided into 9 dangerous areas of rock burst,including 4 medium dangerous areas and 5 strong dangerous areas.Combined with the actual conditions of No.5301(South)working face in Jisan coal mine,through large-diameter borehole pressure relief,roof hydraulic fracturing,floor blasting loosening and bottom breaking,the impact risk area of the working face is greatly reduced,with remarkable effect.There are 43 figures,15 tables and 61 references in this paper.