Research On The Prediction Of Ground Stress And Surrounding Rock Stability Of Jinfeng Gold Mine In Southwest Guizho

The prediction of ground stress is an important content in integrating geological engineering.The occurrence conditions of the orebody in the Jinfeng gold mine in southwestern Guizhou are complicated.With the increasing mining depth,the stress in the interior of the mine area increases significantly,and the instability of the roadway surrounding rock becomes increasingly severe.The in-situ stress test alone needs to meet the requirements of mine mining design guidance.Based on the engineering background of Jinfeng Gold Mine,this paper adopts the methods of field investigation,in-situ test,physical experiment,machine learning,and numerical analysis to research the ground stress prediction and roadway surrounding rock stability of Jinfeng Gold mine in southwest Guizhou.Based on the fitting analysis of the in-situ stress measurement data in southwestern Guizhou and its surrounding areas,the nonlinear boundary conditions for predicting the in-situ stress field in the Jinfeng gold deposit are determined.The in-situ stress measurement method of stress relief method and the Kaiser effect of acoustic emission was used to measure the in-situ stress at several points in the Jinfeng gold mine.Based on the alternative model accelerated optimization algorithm of BP-GA,the ground stress prediction model of the Jinfeng gold deposit in southwest Guizhou is constructed.Selected 30 W vein of Jinfeng Gold Mine as the research object,carried out the stability analysis of roadway surrounding rock with high ground stress,and proposed a reasonable support scheme.The research results are as follows:(1)Through the field investigation of the study area,master the geological characteristics of the study area,such as landform,stratigraphic lithology,geological structure,and other geological data,and collect the geological map,exploration line section,borehole information,and other geological data to establish a three-dimensional geological model;Mechanical parameters of rock mass were obtained through rock mechanics tests,and the three-dimensional geological model and mechanical parameters of rock mass were imported into the finite difference software to obtain the three-dimensional geo-mechanical model.(2)The in-situ stress measurement at 50 m and 30 m levels of the Jinfeng Gold mine was carried out by stress relief combined with the acoustic emission method,and the in-situ stress data of the measuring points were obtained.Moreover,the results of in-situ stress measurement based on the Kaiser effect of acoustic emission at the 30 m level are similar to those of the stress relief method,and the relative errors of principal stress are all less than 15%.(3)Through the appropriate analysis method,the statistical data of ground stress are analyzed,and the boundary load forms imposed by geo-mechanical models in the process of ground stress prediction are proposed.The prediction model of ground stress is established based on the alternative model accelerated optimization algorithm of BP-GA,and the predicted value of ground stress has good consistency and regularity with the measured value.The ground stress environment of the deep orebody in the Jinfeng gold mine is complicated,and the stress level is high.The maximum principal stress of the 30 m middle section is 22～25 MPa,and the maximum principal stress of the 0 m middle section may reach 24～26 MPa.When the mining depth reaches-250 m,the maximum principal stress will reach more than 30 MPa,and the rock mass will be ultra-high.(4)Extract the ground stress vector field data in the 30 W outer vein roadway area to obtain the distribution characteristics of the initial stress field of the 3D numerical model;The RQD value of rock mass in the middle 30 m section is statistically calculated based on the geological borehole data of mine.The average RQD value of the area outside the vein of 30 W is 32.15%,indicating that the overall rock mass quality is poor.The combined support scheme of pipe joint bolt-resin bolt-steel mesh and shotcrete fiber is proposed,and the support scheme is analyzed numerically.After the support,the surrounding rock deformation is small,and the plastic zone volume is reduced by 53.36 %.This support scheme carried out field tests on the 30 W outer vein roadway.After supporting the roadway with this support scheme,the overall deformation of the roadway surrounding rock was small,there was no apparent damage phenomenon on the roadway surface,and the surrounding rock stability was good.