Laboratory testing and analysis of dynamic and static resilient modulus of subgrade soil under various influencing factors

In this study, dynamic and static resilient modulus of subgrade soil were conducted for six types of sub grade soil using the stress level and loading range on top of subgrade under moving vehicle loading. The influences of loading frequency, stress level, compaction degree, and moisture content on dynamic and static modulus were investigated. The prediction models of nonlinear parameters of dynamic resilient modulus and the relationship of dynamic and static resilient modulus were developed. Results showed that dynamic resilient modulus of different soils were significantly affected by loading frequency at the loading frequency range of 0.5-3 Hz. Dynamic and static resilient modulus were both positively related with confining pressure and compaction degree, but negatively related to the moisture content of subgrade soil. The nonlinear parameters of dynamic resilient modulus prediction models had the similar form for different types of subgrade soil, while the coefficients of nonlinear parameters varied with the type of subgrade soil. The parameters of the relationships between dynamic and static resilient modulus for different types of soil were also similar in the equation format with different parameter values. The research findings provide valuable information for using realistic subgrade soil modulus in pavement design and analysis. (C) 2018 Elsevier Ltd. All rights reserved.