Study On Deformation Law And Control Of High Stress Roadway In Lower Part Of Multi-coal Seam Mining In Close Distance In Jinhuagong Mine

In the mining of close distance coal seams,due to the different mining height of the lower coal seam and the distance between the coal seams,the overlying strata show different structural characteristics in the mining process of the lower coal seam,and different roof structure characteristics will cause different mine pressure behaviors in the working face.Under the influence of various stress superposition,multi-seam mining will cause the deformation of the lower coal seam excavation roadway to increase significantly,the roof is broken and difficult to support,and the mine pressure problems such as serious damage to the supporting components appear.Based on the engineering background of 5718 11^-1#mining roadway in the lower part of 7^-3#and 7^-4#in Jinhuagong Mine,this thesis analyzes the deformation and failure law and control method of high stress roadway in the lower part of close distance multi-seam mining by means of field observation,physical test,numerical simulation and theoretical analysis.Combined with the results of similar simulation experiment and numerical simulation analysis,the support method to control the stability of high stress roadway in the lower part of close distance mining is put forward and verified by engineering.The main work and conclusions are as follows:（1）The field observation shows that the mining pressure of 11^-1#coal mining roadway is strong under the influence of upper 7^-4#coal seam mining.（2）The stress distribution of 11^-1#coal mining roadway under close distance coal seam mining in Jinhuagong Coal Mine is measured by drilling cuttings method.The amount of drilling cuttings in the coal pillar side is higher than that in the coal side of the working face,and the high stress area is mainly concentrated in 6～10m,while the drilling peep shows that the maximum 3.5～4.0m of the surrounding rock loose circle corresponds to the low stress area measured by drilling cuttings.The numerical simulation shows that the vertical stress distribution of the two sides conforms to the general stress distribution form,and the stress of the coal pillar is larger than that of the solid side.The peak stress is 20.0MPa and 16MPa respectively,and the peak depth is4.2m and 5.3m respectively.（3）The physical simulation shows that the stability of the roadway during the excavation period can be guaranteed when the steel shed support and bolt support are used in the high stress mining roadway under the close distance mining.However,when the mining abutment pressure of the working face is applied,the deformation of the surrounding rock of the roadway reaches 5 to 10 times during the excavation period and fails.The control ability of the steel shed support to the deformation of the surrounding rock is weaker than that of the bolt support,and the use of the yielding bolt anchorage can effectively stimulate the surrounding rock to form an arch.Even under the influence of the subsequent strong support pressure,the stability of the surrounding rock of the high stress roadway can still be maintained.Anchoring support is more suitable for roadway support with large deformation of surrounding rock because it does not destroy and fail when the deformation of surrounding rock is large,and the rock mass in the strengthened range does not collapse.（4）After the excavation of Jinhuagong 5718 roadway,the surrounding rock within 5.0m of the roof and floor is in an unstable state,while the deep part is in a stable state.The stress concentration area in the side is the main factor affecting the stability of the roadway.Through the combined support of the pressure-equalizing anchor cable and the pressure-relief hole,the stress distribution characteristics of the coal and rock mass in a large range can be changed while maintaining the stability of the surrounding rock.The phenomenon of stress concentration in the side can be eliminated and the large deformation and instability of the surrounding rock can be reduced.（5）The combined support scheme of high resistance yielding bolt+yielding bird’s nest anchor cable+steel mesh+drilling pressure relief in 5718 roadway of Jinhuagong Mine was designed,and effective field application effect was obtained.There are 63 figures,18 tables and 62 references in this thesis.