Evolution Characteristics Of Surrounding Rock Deformation And Its Control Technology Of Gob-Side Entry Retaining By Roof Cutting

As the development direction of non-pillar mining technology,the gob-side entry retaining by roof cutting and pressure releasing have broad development prospect.Nevertheless,due to the long service period of the roadway,the deformation and damage of the roadway surrounding rock is severe.Especially during the period of gob-side entry retaining by roof cutting and pressure releasing,the deformation and damage of the surrounding rock of the roadway becomes more and more conspicuous.In this paper,a variety of research methods and methods such as theoretical analysis and derivation,physical experiment simulation,numerical simulation calculation and field measurement are used to establish the mechanical model of roof structure evolution during the process of gob-side entry retaining by roof cutting and pressure releasing,and expound systematically the law of overlying rock structure movement and the characteristics of deformation and failure of surrounding rock of gob-side entry retaining by roof cutting and pressure releasing,and reveal the deformation evolution of surrounding rock of gob-side entry retaining by roof cutting and pressure releasing,and propose the stability control principle and plan of gob-side entry retaining by roof cutting and pressure releasing,and discusses the change trend of surrounding rock of gob-side entry retaining by roof cutting and pressure releasing in XV1306 working face of Yixin Coal Mine.The main research results are as follows:(1)Based on the technical principle and technological process of non-pillar gob-side entry retaining by cutting roof,the evolution process of roof structure and the law of mechanics transfer of gob-side entry retaining formed by cutting roof are expounded,and a simplified model of roof mechanics is established in the entire gob-side entry retaining process.The calculation formula of roof stress distribution and deflection deformation in diverse stages is derived.The analysis represents that the deformation of surrounding rock in the dynamic pressure affected area is the most severe in the process of gob-side entry retaining by roof cutting and pressure releasing.(2)The similar material test was used to study the caving and migration law of the roof of the mined-out area,under the conditions of gob-side entry retaining formed by roof cutting and pressure release of non pillar mining technology.The results represent that:when the working face was excavated to 30m,there are slight lateral cracks on the top roof,but the roof has not yet shown signs of collapse;when the working face was excavated to 45m,the immediate roof of the goaf emerges to cave at the first time,and the precast cutting roof can reduce the incidence of overburden fracture on the roadway.(3)The deformation law of surrounding rock and the distribution characteristics of supporting pressure of gob-side entry retaining formed by cutting roof are simulated by using the numerical analysis software FLAC3D.The results demonstrate that during the coal mining operation,the range of roadway support pressure affected by mining is 60m in front of the working face to 240m behind.Among them,the area with the largest mining disturbance is 30m in front of the working face to 50m behind the working face.The roof rock beam moves obviously,the surrounding rock bearing pressure increases significantly,and the amount of deformation also increases rapidly,and the roof sinking amount on the slit side is more important than that on the solid coal side.(4)According to the theoretical analysis,physical simulation experiments and numerical calculation analysis results,the stability control principle of the roadway surrounding rock in no gate side pack top cutting pressure relief of gob-side entry retaining which put together of"dynamic prevention and control in different stages" and "stress field optimization of surrounding rock in gob-side entry retaining" and "matching and coordination of gob-side entry retaining surrounding rock supported" and "reinforcing support for key positions" were proposed;at the same time,the design scheme of the surrounding rock support of gob-side entry retaining formed by roof cutting with the hard roof is proposed.(5)Through real-time monitoring of the occurrence of the rock pressure of the surrounding rock of gob-side entry retaining formed by roof cutting in the XV13 06 working face of Yixin Coal Mine.The results represent that:under the influence of the rotation deformation and collapse of overlying rock beams in the mining space,the deformation law of the surrounding rock around the roadway can be roughly divided into three stages:in the rear of the working face,the 0-50m range is the intense stage of the gob-side entry retaining of surrounding rock movement,in the rear of the working face,the 50-200m range is the section of the roadway where the surrounding rock movement is slow,after the distance of the lagging working face exceeds 200m,the surrounding rock movement tends to be stable.The industrial tests have successfully evidenced the reasonableness and reliability of the technological process of gob-side entry retaining by roof cutting and pressure releasing and the rationality and reliability of the research conclusions.