Study On Slope Stability Analysis Method Of Open-pit Mine Based On Barton-bandis Nonlinear Failure Criterion

The rock mass is an important part of the rock slope.As a geological body,it has undergone long-term repeated geological processes and process of deformation and failure,certain rock components and structures have been formed and existed in some geological environment.The rock mass is composed of joints and structure cut by the joints,and rock mass often has sliding damage along the joints,so the shear performance of the joints is crucial for the stability of the rock mass.In this paper,three characteristic parameters which characterize the shear behavior of rock mass joints are selected for sensitivity analysis,and the stability trend of slope stability coefficient with various parameters is determined at first.Secondly,in view of the fact that the value of the shear strength parameters in the transfer coefficient method cannot adapt to the actual force of the potential slip surface,only when the shear strength parameters satisfy the Mohr-Coulomb criterion,it is accurate to evaluate the slope stability of different scales by using the same shear strength parameters for each bar,a limit equilibrium analysis method for slope stability based on Barton-Bandis nonlinear failure criterion was proposed.Finally,considering the nonlinear characteristics of rock mass strength due to the influence of roughness and compressive strength of rock mass joints,the traditional limit equilibrium method uses mean to characterize the physical and mechanical indexes of rock mass,so that the evaluation conclusion can't take into account the discrete nature of the index,a slope failure probability analysis method based on Barton-Bandis nonlinear failure criterion was proposed.The methods were verified and compared with the results of traditional limit equilibrium analysis.The specific research results are as follows:(1)Through field geological survey and indoor data processing,multiple sets of sample data of parameters such as rock mass joints'roughness coefficient JRC,rock mass strength JCS and basic friction angle?_bare obtained.After the probability distribution test and sensitivity analysis,it can be found that there are randomness and uncertainty in the parameters,and this uncertainty will affect the accuracy of the slope stability analysis results.(2)The equivalent linear fitting of the shear strength parameters of the Barton-Bandis criterion to the Mohr-Coulomb criterion is obtained by the tangent equivalent method.The value of the shear strength parameters in the transfer coefficient method does not take the actual normal load acting on the slip surface into account the actual effect on the slip surface.A limit equilibrium analysis method for slope stability based on Barton-Bandis nonlinear criterion was proposed and compared with the calculation results of transfer coefficient method to verify the effectiveness of the new method.(3)Based on the Barton-Bandis criterion,a stability analysis model of a mine slope was established.Based on the distribution of shear strength parameters(JRC,JCS,?_b)of the joints,the Morgenstern-Price method was used to establish the damage limit state function of the rock slope.The Monte Carlo method was used to generate multiple sets of random numbers for each parameter,and the multiple sets of stability coefficients of the slope were calculated.The damage probability of the slope was determined by the statistically analyze of Monte Carlo method.A slope failure probability analysis method based on Barton-Bandis nonlinear criterion is proposed and compared with the traditional limit equilibrium analysis method to verify the effectiveness of the new method for evaluating slope stability.