Study On Coal Pillar Stability And Surrounding Rock Control Technology For Gob Driving In Xieqiao Mine

The 21316 track trench in Xieqiao Coal Mine is a typical roadway driven along the goaf under an unstable goaf structure.The strength of the coal body is weak,and the roadway structure in some sections is developed,and the roof occurrence is unstable,resulting in stress concentration and overall subsidence,affecting the safe production of the working face.In order to study the stability of the surrounding rock of the 21316 track chute in Xieqiao Mine under the influence of unstable goaf,based on the methods of mechanical property tests,numerical simulation analysis,theoretical derivation,and field tests,this thesis studied the stress distribution and deformation characteristics of the surrounding rock of the roadway at different stages,revealed the law of the stability of the surrounding rock changing with the rock stratum inclination,lateral pressure coefficient,and coal pillar width,and proposed an effective control plan for the surrounding rock.The main content of the thesis is as follows:1.Through laboratory mechanical tests,the rock mechanical properties of different rock layers were tested,and parameters such as compressive strength,tensile strength,adhesive force,and internal friction angle of the roof,floor,and coal seams were obtained,providing support for subsequent numerical simulation analysis.2.Based on simulating the stress distribution and deformation characteristics of roadways under different rock dip angles and lateral pressure coefficients,the influence of rock dip angles and lateral pressure coefficient changes on the stability of surrounding rock is explored.Using the simulation results under the same rock stratum inclination angle and the same lateral pressure coefficient,the differences in the stability of surrounding rock between the inclined roof trapezoidal section and the three-core arch section are compared and analyzed,and the advantages of the threecore arch section in controlling the surrounding rock of the roadway are clarified.3.Using the method of numerical simulation,the stress distribution,deformation characteristics,and plastic zone development of roadway surrounding rock under different pillar widths during the excavation and mining stages were investigated in detail.By theoretical calculation,the minimum width of the coal pillar was determined,and a 5m wide coal pillar was used for roadway excavation,taking into account the stability of the surrounding rock of the roadway and the recovery rate of the coal seam.4.Guided by the continuous beam theory,the necessity of roadway support is clarified through theoretical calculation of roof deflection without support,and the impact of support schemes with different bolt lengths and preloads on roof deflection is revealed.Based on the comparative analysis of the stress distribution and deformation characteristics of the numerical simulation results of different support schemes,a control scheme for the surrounding rock of the 21316 track trench is proposed.Using an industrial test method,the roof separation amount,roadway surface displacement,and anchor bolt(cable)load of the roadway test section were observed.While testing the reliability of the surrounding rock control plan,the effect of different cross sections and different coal pillar widths on the stability of the surrounding rock was also verified.This thesis has 44 figures,7 tables,and 85 references...