Study On Control Technology Of Surrounding Rock In Roadway Of Isolated Island In Thick Coal Seam

The old roof of the mined-out area on both sides of the isolated face fractures,the overlying rock stratum is violently active,the mining pressure is high,the surrounding rock stress is highly concentrated,and the surrounding rock of the roadway is seriously deformed and damaged to a high degree.Based on the research background of 4206 fully mechanized top coal caving island in Jianxin Coal Mine,this paper focuses on the stress distribution and structural characteristics of the overburden strata on the island of top coal caving face,reasonable coal pillar width and roadway support method.Firstly,the structure and stress distribution of overlying strata during the formation and mining of isolated island fully mechanized caving face are analyzed.The deformation and failure characteristics and bearing capacity of coal pillars vary from shallow to deep.The goaf collapses and the low-level rock beams are formed.Unstable short cantilever beam structure,its fracture line tends to goaf on both sides,and the amount of roof separation on the working face is large.Secondly,theoretically systematically analyze the surrounding rock stress and the width of the plastic zone in the limit equilibrium zone of the section coal pillar.And use numerical simulation software to compare and analyze different width coal pillar retention schemes.From the changes of the stress field,displacement field and plastic zone of the roadway surrounding rock during driving and working face mining,it can be obtained that The increase in the bearing capacity of the coal pillars and the reduction in the deformation of the surrounding rocks.The stability of surrounding rock is high when the coal pillar width of 4206 transportation roadway is 15 m.Based on the self-stabilizing stealth arch theory,the difference of the control effect of different support methods on the surrounding rock deformation of the tunnel is studied.The use of high-strength anchors and strong extension cables,the application of high preload and enhanced surface protection can effectively increase the bearing capacity of the surrounding rock.Finally,relying on Jianxin Coal.Mine’s 4206 island top-coal caving face to carry out industrial tests,actually measured and summarized the surrounding rock deformation law of the mining roadway in the island top-coal caving face,and analyzed the rationality of the roadway support methods and parameters.The field application results show that the tunnel surrounding rock deformation control effect is better,and the support-wall rock is in a steady state.It reflects the rationality of coal pillar retention and support form,and has guidance and reference significance for the mining of similar island working face.