Study On Dynamic Strength Properties Of Lightweight Loess-EPS Beads Soil Under Cyclic Loading

Light weight soil is a new kind of mixture materials which is composed of raw material soil,lightweight materials,hardeners and water mixed according to a certain ratio.In general,sand,clay or construction engineering waste soil is used for raw material soil,expanded polystyrene or foam plastic particles is usually taken as lightweight materials,cement is taken as hardners and tap water or non-polluted water is used for water.Under the joint action of these raw materials,Light weight soil is environmentally friendly,light weight,high strength,strong plasticity,and has good heat insulation characteristics.Besides,it's density and strength can be adjusted,so it has a wide range of engineering applications.Moreover,in practical applications,Light weight soil is mainly used as filling materials in highway projects,thus will inevitably be affected by traffic,earthquakes,and other loading.At present,there are few studies on the dynamic characteristics of Light weight soil,and the existing research results mainly focus on dynamic deformation.The lack of systematic and comprehensive research on the dynamic strength characteristics has led to insufficient understanding of the dynamic strength characteristics of Light weight soil.In view of this,this paper selects loess in Shaanxi Fufeng area as raw material for the preparation of Light weight loess-EPS beads soil,and uses the SDT-20 type micro-controlled electro-hydraulic triaxial apparatus to perform dynamic triaxial tests on Light weight loess-EPS beads soil.The main works and conclusions are as follows:(1)Statistical analysis is conducted on the density of Light weight loess-EPS beads soil with different proportions.It can be found that the density of Light weight loess-EPS beads soil in this experiment is between 0.60 g/cm~3 and 1.50 g/cm~3,among which the EPS contents have the greatest impact on the density of Light weight loess-EPS beads soil.The cement contents have little effect on the density,and the curing periods have almost no effect on the density.(2)When the other influencing factors are fixed,the unconfined compressive strength of Light weight loess-EPS beads soil decreases with the increase of EPS contents,and the decreasing trend is nonlinear.And,the unconfined compressive strength of Light weight loess-EPS beads soil with different proportions increases while the curing periods are increasing.The unconfined compressive strength of the Light weight loess-EPS beads soil is in the range of 103.2kPa~1359.0kPa.(3)The experimental results show that the internal pores of Light weight loess-EPS beads soil are relatively developed and therefore cannot be saturated.Moreover,under the action of dynamic loading the dynamic strain does not change abruptly with the increase of the number of dynamic loading.In addition,as the number of dynamic loading increases,the compressive strain gradually exceeds the tensile strain,showing a clear bias phenomenon.Therefore,5%compressive strain is chosen as the failure criterion for Light weight loess-EPS beads soil in this test.(4)The dynamic strength of light weight soil mixed with EPS beads increases by the increase of cement content and confining pressure,but decreases by the increase of EPS content.And the dynamic strength of light weight soil mixed with EPS beads is larger than that of remolded loess,and the dynamic strength of light weight soil mixed with EPS beads with different increased ratio is 20.8%~232.9%.(5)The cement contents and EPS contents have a great influence on the dynamic strength parameters of Light weight loess-EPS beads soil.With the increase of the number of dynamic loading,the dynamic cohesion of Light weight loess-EPS beads soil decreases,and the dynamic internal friction angle is basically unchanged,and the?_d-N curve is a horizontal line.Both of the dynamic strength parameters can be fitted with logarithm curve.