Study On Dynamic Characteristics Of Light Soil Mixed With Silt And Rubber Particles

With the continuous development of automobile industry and road transportation,more and more waste tires are produced,and the problem of disposal of waste tires is increasingly prominent.The rubber particles produced by waste tires have the characteristics of light weight,good permeability,high friction and high damping,so they are mixed with sand as light fillers and used in the engineering field.At the same time,as the poor soil in the process of road construction,silt is difficult to compact.Under the dynamic load,capillary water is easy to rise,which affects the stability of road bearing capacity.Using waste tire rubber mixed with silt to solve the problem of silt as subgrade filler.In this paper,the dynamic characteristics of the silt rubber granular soil are studied through compaction test,capillary water rising test,dynamic triaxial test,dynamic response model test and numerical simulation.The specific contents and results are as follows:In the first part,the influence of rubber content and rubber particle size on the compaction and capillary water properties of silt was studied by compaction test and capillary water rise test.It is found that the maximum dry density of the mixed soil decreases with the addition of rubber particles,and the higher the rubber content is,the lower the maximum dry density is.At the same time,adding rubber particles makes the mixed soil easier to be compacted,the optimal moisture content of the mixed soil decreases,the optimal moisture content of the large-size rubber mixed soil decreases with the increase of rubber content,and the optimal moisture content of the small-size rubber mixed soil is independent of rubber content.The capillary effect of the mixed soil decreased significantly.The higher the rubber content,the slower the rising speed of capillary water and the lower the rising height.In the second part,the influence of confining pressure,rubber content and particle size on the damping ratio and dynamic elastic modulus of mixed soil was studied by dynamic triaxial test.It is found that the dynamic elastic modulus of the mixed soil decreases and the damping ratio increases with the addition of rubber particles.The dynamic elastic modulus of the mixed soil increased with the addition of confining pressure and particle size,and decreased with addition of rubber content;the damping ratio is completely opposite to the dynamic elasticity modulus.At the same time,based on the hyperbolic model,the empirical formula of the maximum elastic modulus(E_d,max)of the mixed soil is established,and the model of the dynamic modulus ratio(E_d/E_d,max)and damping ratio（λ）with the change of strain（ε_d）are established respectively.In the third part,the dynamic characteristics of pipeline in mixed soil and mixed soil were studied by model test.It is found that the rubber mixed soil can effectively reduce the settlement of subgrade surface,the increment of earth pressure and the deformation of pipeline under the dynamic load.With the increase of rubber content,the smaller the increment of earth pressure and pipe deformation,which means the better vibration reduction.In addition,it is found that the strain at the top of the pipe is alw ays concave during the loading process,while the deformation at the bottom of the pipe experiences a change process from tensile strain to compressive strain with the increase of the load.In the fourth part,the dynamic characteristics of mixed soil and pipeline in mixed soil were studied by numerical simulation.It is found that under dynamic load,the surface settlement,acceleration and pipe strain of the mixed soil with different rubber content are significantly different.The internal settlement and acceleration of soil layer have little influence on the condition of small rubber content,but it starts to decrease significantly from 30%,and the rubber mixed soil can effectively reduce the settlement and acceleration under the mixed soil layer;the rubber content of 30%can effectively reduce the pipe deformation,so the vibration reduction of 30%content is significant.