Abstract: At the same time,optimizing support design and improving support effect are the urgent requirements of mine development in the new era.But at present,there is a lack of design specifications for roadway support in metal mines.The design and construction scheme mainly rely on simple empirical formulas and lack of corresponding theoretical basis.Based on the theory of HoekBrown strength criterion and geological strength index GSI,this paper realizes the random assignment of mechanical parameters of rock mass quality grade,innovatively puts forward the calculation method of safety factor of support effect,and carries out numerical simulation analysis of plain shotcrete support in different grades of rock roadway.Combining the model calculation data with big data statistical analysis,the empirical expressions of the minimum safety factor for different rock mass quality grades,different support parameters and support effects are established.The research results show that the rock roadway support effect can be analyzed based on the self assignment of surrounding rock mechanical parameters based on the strength theory and combined with the numerical simulation software,which is in good agreement with the engineering site.By confirming the stress control threshold,the section safety factor envelope can be drawn to visually find the weak points of the support system for pre reinforcement.The research results provide an effective method for the safety evaluation of plain shotcrete support effect of surrounding rock with different quality grades,which can be used for reference in practical engineering design.

Key words: metal mine,Hoek Brown strength criterion,numerical simulation,rock mass grade,minimum safety factor