Research On Surrounding Rock Control Technology Of Roadway Under Irregular Coal Pillar

In view of the mining of the working face under the overlying irregular coal pillars and the technical problems of roadway surrounding rock control,this thesis takes the21511 working face of the south first mining area of Xiangshan Mine as the research object,and analyzes the roadway support conditions under similar conditions through field investigation.Based on theoretical analysis and numerical simulation,the stress distribution and variation law of surrounding rock caused by mining are analyzed,and the influence degree of abutment pressure on mining roadway in different areas of21511 working face is obtained.Aiming at the problem of low anchoring force of coal side in Xiangshan Mine,the field anchor cable anchoring performance test was carried out to explore the reasons and propose solutions.An anchor net support scheme under irregular coal pillar in mining roadway of 21511 working face was proposed and tested in test roadway.The main results include:（1）The mining roadway of 21511 working face belongs to the typical’strong roof and weak side’roadway.The failure characteristics of similar roadway surrounding rock are mainly roof subsidence,two sides moving inward and floor heave.Through in-depth field investigation and research,it is concluded that the strength of roadway surrounding rock,the structure of roadway surrounding rock,the influence of dynamic pressure,the overlying residual coal pillar and the quality of roadway support are the main reasons affecting the deformation and failure of roadway surrounding rock.（2）Combined with the actual geological and mining conditions of 21511 working face,the FLAC^{3 D} is used to analyze the vertical stress evolution law of coal pillar and coal body during the mining process of 21511 working face under the influence of irregular coal pillar.It is concluded that the influence range of 21511 working face mining on the advance abutment pressure of coal body in front of it is 80 m.In addition,according to the variation law of surrounding rock stress,the minimum abutment pressure of 21511 working face mining roadway is located below the goaf of 3#coal seam,and is not affected by the abutment pressure under the coal pillar of 3#coal seam or less affected by the lateral abutment pressure of 5#coal seam.The maximum bearing pressure is located under the coal pillar left after the mining of 3#coal seam,and the roadway is affected by the superposition of multiple working faces in the vicinity.（3）By constructing a mechanical model,the stress of the roadway roof under non-uniform stress conditions is analyzed.According to the relative position relationship between roadway and coal pillar and the degree of roadway affected by mining,the mining roadway of 21511 working face is divided into three categories.Based on theoretical calculation and numerical simulation,the bolt and cable support parameters of coal pillar influence section in 21511 working face are obtained,and the surrounding rock control technology of roadway under irregular coal pillar is put forward.（4）Considering the geological and mining conditions of the return airway in the21511 working face and the stress characteristics of the surrounding rock,the numerical simulation software was used to analyze the stress distribution law of the roadway surrounding rock and the displacement of the roadway surrounding rock at 0m,10m and 20m away from the edge of the goaf.The reasonable position of the return airway in the 21511 working face was determined,and the rationality of the anchor net support scheme was analyzed.（5）The effect of anchor net support on site shows that when the return airway of21511 working face is 20 m away from the edge of overlying goaf,the anchor net support technology scheme under the influence of coal pillar can effectively control the deformation of roadway surrounding rock under irregular coal pillar during roadway excavation.The thesis has 72 figures,9 tables and 97 references.