Numerical Simulation Research On Macro And Micro Characteristics Of Rubber-Sand Mixture Under Different Stress Paths

With the strengthening of people’s awareness of environmental protection and the rapid development of the automobile industry,waste tires have received increasing attention in terms of recycling and reuse.As rubber materials have strong deformability,low permeability and good thermal insulation properties relative to the soil,they are often mixed with sand as a lightweight geotextile and applied to the backfill of roads and slopes,which can improve the strength of the soil and also widen it.Ways to deal with solid waste resources.In recent years,the discrete element method based on the discontinuous medium theory has been widely used in the geotechnical field.Based on the discrete element method,this paper deeply studies the macro and micro mechanical properties of rubber sand.Through a series of true triaxial numerical simulation experiments,the mechanical deformation characteristics of rubber sand under different complex stress paths are studied,with emphasis on the influence of rubber particle content.The main research contents and results of this paper are as follows:(1)Based on the discrete element method,a series of true triaxial numerical simulation tests of rubber sand mixture under different stress path conditions are carried out,and the anti-rotation linear contact model considering the rotation resistance is analyzed and selected,and the rubber sand parameter calibration is carried out.(2)Under the path of equal principal stresses,explore the influence of the middle principal stress ratio on the macromechanical properties of rubber sand with different rubber content,and analyze the influence mechanism of the middle principal stress ratio from a microscopic point of view.Numerical simulation results show that as the ratio of intermediate principal stresses increases,the peak deviator stress gradually increases,while the peak internal friction angle first increases and then decreases;comparing the numerical simulation results with the commonly used strength criteria,it shows that the existing commonly used criteria are not very good Predict the damage state of rubber sand.At the micro level,the analysis of the principal stress ratio and rubber content has an effect on the coordination number,average normal stress between particles,probability density and anisotropy.(3)Under the equal average stress path,study the influence of rubber content on the deviatoric stress ratio and volumetric strain during the shearing process,and reflect the deformation characteristics of rubber sand through the relationship between principal strains and the evolution of principal strains,and based on the π plane Compare the four commonly used three-dimensional strength criteria.At the micro level,the contact analysis coordination number,probability density,average normal contact force and three-dimensional histogram reflect the microscopic contact changes of the rubber sand particle assembly;and based on the fabric anisotropy coefficient,it quantitatively reflects the relationship between the rubber content and the contact normal and method.To the influence of contact force.Finally,through the fabric-stress development model,the macro and micro combined analysis anisotropy.(4)Analyze the fabric development characteristics of rubber sand under two different complex stress paths.Based on the fabric-strain development model of fabric tensor,the rubber sand has three kinds of fabric components,partial fabric and strong partial fabric.Analysis of fabric change with axial strain;and quantitative analysis of non-coaxiality of rubber sand.Further analyze the influence of different stress paths and rubber content on the peak value of the overall partial fabric,the peak value of the strong partial fabric and the non-coaxiality of the peak state.