Construction Of Layered Rock Mass Material Model And Stability Analysis Of Stope In A Gem-jade Mine

The ore in the gem-jade mine that lies in eastern Guizhou is very thin.The surrounding rock of ore is slate,which is exploited by backfill mining method.For safety and efficiency,physical and mechanical tests are designed to explore anisotropic properties of slate.Combined with which,P wave test was used to analyze layer properties.When the layer and the direction of shear load combination relations was changed,strength anisotropy was researched.Numerical simulation method was used to find if the numerical model can simulate the different failure model.So the numerical model with reduced rock mass parameters was used to analyse the stability of underground stope with layered rock mass.Some helpful conclusions are as follows:(1)Results showed that layer surface of slate in the eastern part of guizhou cements closely,large mineral grains between the layers is less and shale particles is more,layer surface is smooth and uniformly distributed.Shear strength is related to the loading direction and layer plane Angle,when layer is paralleled to loading direction,cohesion is 7.394 MPa and friction angle is 11.96°.When the loading direction is perpendicular to the layer in some plane,cohesion is 10.965 MPa and friction angle is 9.18°.(2)Based on the results of the tests,the joint material model of ABAQUS/Standard is setup to simulate the test of rock loading condition,the study showed that it can reflect the failure model of shear tests.Then the numerical model which can reflect layer properties was established.(3)Stability analysis of stope with the angle of 20° showed that the largest width is 9m.In the process of increasing stope width,plastic flow and the shear failure may occur in the upper edge part.In the process,the stope on both sides of the upper region is most likely to be tensile failure.Vertical deformation in the middle of roof increase 41.9%,roof fracture that may occur in the middle should be paid more attention.After reaching the deformation limit,roof will give priority to breaking from the middle.(4)When stope layout direction that is parallel to the bedding plane,increasing the angle,shear stress increased four times as much.High stress area gradually concentrated to the upper part of the stope edge,where the plastic zone expanded significantly.To control the roof stability,when angle is small,vertical displacements on the central part of roof should be paid attention to.When angle is bigger,roof will give priority for the shear stress failure.