Experimental Study On Static And Small Strain Dynamic Characteristics Of Rubber-Sand Mixture

As a new and developing granular material,rubber-sand mixture has the characteristics of both rubber and sand materials and plays a unique role in some engineering fields,such as the application of light backfill soil and isolation layer.However,due to the physical and mechanical properties of rubber-sand mixture are affected by the shape,particle size ratio,content proportion,gradation and other factors of the two kinds of granular materials,there are still large differences in the related static and dynamic properties.Thus,in this paper,a series of compression,shear and resonant column tests were conducted to explore static and dynamic characteristics under small strain of rubber-sand mixtures.The research results can provide a basis for the related scientific studies and further exerting the application potential of rubber-sand mixture in engineering practice.The specific research contents and results are as follows:(1)Through the cyclic compression and direct shear tests of rubber-sand mixtures,the compressibility related indexes such as compression coefficient,density and void ratio of the mixtures with various rubber contents were systematically analyzed and compared.The influence of rubber content on the compressibility of mixtures was evaluated.Finally,the static shear strength of the mixtures was further studied,and the results show that the addition of rubber will weaken the maximum shear strength of soil.(2)A series of resonant column tests were carried out on rubber-sand mixtures under normal consolidation.The dynamic characteristics of the mixtures under small strain were investigated,revealing the influence of rubber content and confining pressure on the damping ratio,dynamic shear modulus,the normalized damping ratio and the normalized dynamic shear modulus.It is found that the addition of rubber can increase the damping ratio of soil.Also,the dynamic shear modulus of the mixture with 10% rubber content is the largest under the condition of high confining pressure.(3)By analyzing the dynamic characteristics of rubber-sand mixtures under different overconsolidation ratios,the effect of law of overconsolidation ratio on the basic indexes such as the damping ratio and dynamic shear modulus of the mixtures,and their microscopic mechanism were revealed.Normalized dynamic shear modulus equations of the mixtures with various overconsolidation ratios were presented.Finally,based on the analysis method of stress ratio,a more convenient method for predicting dynamic shear modulus and damping ratio of mixtures under small strain range was presented.