Study On The Influence Of Particle Shape And Average Particle Size Ratio On The Dynamic Characteristics Of Rubber-sand Mixtures

With the rapid development of automobile industry,waste tires have become one of the main solid wastes facing the society.How to use them efficiently and beneficially has become a serious issue.The rubber-sand mixture is a mixture of waste rubber particles / fragments and natural sand in a certain proportion.It has the engineering characteristics of light weight,strong elasticity,high damping and low modulus.It can be used in the fields of retaining wall backfill,pipeline protection,vibration suppression and energy dissipation,base isolation and other civil engineering fields.The dynamic characteristics of soil,as a necessary parameter for the analysis and design of all kinds of geotechnical structures under earthquake,traffic,blasting,wave and other dynamic loads,has always been an important research topic in the field of earthquake and geotechnical engineering.In this paper,based on the research results,combined with the small strain resonance column test and discrete element particle flow micro analysis,the effects of particle characteristics,average particle size ratio and mix ratio of two materials on the dynamic characteristics of rubber particle sand mixture are deeply studied and revealed,and the empirical formulas of maximum dynamic shear modulus,dynamic shear modulus ratio attenuation curve and damping ratio curve of the rubber-sand mixture are established to determine the dynamic parameters The characteristic parameters and main matching parameters can provide reference for relevant engineering applications and lay a foundation for promoting the reasonable application of waste tire particles / debris in the field of civil engineering.The main contents are as follows:1.Based on GDS-RCA resonant column system,the dynamic shear modulus and damping ratio of the rubber-sand mixture were studied from the aspects of rubber content,dry and wet state,considering the consolidation confining pressure of 100 k Pa.The dynamic properties of the rubber-sand mixture were analyzed,and the dynamic properties of saturated and dry rubber sand were compared.2.Through GDS-RCA resonant column system,the effects of different average particle size ratio,mass ratio and confining pressure on the maximum dynamic shear modulus,dynamic shear modulus and damping ratio curve of rubber sand were studied.When the volume of rubber particles is regarded as a part of the total pore volume,the empirical formula of maximum dynamic shear modulus of Hardin conventional soil can still be applied to the rubber-sand mixture.3.Through GDS-RCA resonant column system,the dynamic characteristics of the rubber-sand mixture such as dynamic shear modulus and damping ratio under dynamic load are systematically discussed,and the effects of shear strain amplitude,rubber particle shape and consolidation pressure on dynamic shear modulus and damping ratio are analyzed.4.By summarizing the test data,the empirical curve of dynamic characteristics of the rubber-sand mixture is given,the test results are analyzed,and the empirical formula of maximum dynamic shear modulus considering the influence of confining pressure,rubber content and average particle size ratio is proposed.Based on Darendeli’s modified hyperbolic model,the fitting curves of dynamic shear modulus ratio,damping ratio and shear strain of the rubber-sand mixture under various working conditions are given.5.Through the particle flow software,the three-dimensional triaxial compression test discrete element numerical model of the rubber-sand mixture is established.Based on a series of meso scale simulation tests,the effects of proportioning,average particle size ratio and confining pressure on the mechanical and deformation characteristics of rubber sand were analyzed from macro and micro aspects,and the internal mechanism was discussed.6.The above research results show that: there are many factors that affect the dynamic characteristics of rubber sand(small strain shear modulus,damping ratio),and rubber content,confining pressure and average particle size ratio are the main factors that affect the dynamic characteristics of rubber sand.In this paper,the dynamic characteristic empirical curve of rubber sand affected by the above factors is given,in order to provide reference for people to understand the influencing factors of dynamic characteristics of the rubber-sand mixture.