Study On Influencing Factors And Prediction Model Of Dynamic Resilient Modulus Of Laterite Soil Subgrade

Laterite soil,a special soil widely distributing in south moist heat areas of China,has high water content,high liquid and plastic limit,high porosity ratio,low compressibility,micro-expansibility,and also has high strength at the same time.If the laterite soil which has better performance could be reasonably designed,it could be used for subgrade filling.Since the laterite soil of subgrade was a kind of non-linear and uneven material,the resilient modulus has obvious difference at different point of subgrade under repeated traffic load.The resilient modulus has obvious stress dependence.The resilient modulus of subgrade was a key parameter in the design of asphalt pavement structure,and how to value it was very important.In this paper,the laterite soil which come from Yongzhou of Hunan was researched.Through the basic physical and mechanical performance test,the classification and the basic parameters of laterite soil was determined.Based on the analysis of the value range of stress condition,moisture content and compactness,the repeated loading test was developed.Based on the analysis of the influence of different factors on the resilient modulus,several prediction models considering different influence factors were established,and then the range of the resilient modulus could be estimated.Using dynamic triaxial test apparatus,through repeated loading triaxial test,the driving load acting on the subgrade soil could be accurately simulated.The research showed that resilient modulus decreased with the increasing of water content,increased with the increasing of the degree of compaction,and also the influence of the moisture content was more significant;The resilient modulus increased with the increasing of confining pressure,decreased with the increasing of deviatoric stress and body stress,and the influence of confining pressure was more significant.When the confining pressure or the partial stress was low,the effect of the change with this on the resilient modulus was more significant.Based on different influence factors,different resilient modulus models could be established,three kinds of forecast models of resilient modulus were fitted with seven group test datas.Although Uzan model may have the problem of indefinite values,but its correlationwas still better.N37 A model has higher correlation coefficient and smaller discrete.The research showed that dynamic resilient modulus of laterite soil could be characterized by N37 A model.Referencing level of equivalent stress level in the typical road,the corresponding reference value of dynamic resilient modulus of laterite soil of subgrade was proposed.