Resilient modulus of soil using for subgrade of pavement: A case study in Vietnam

Abstract

Resilient modulus (Mr) is one of the crucial parameters, which is used for the design of a multi-layer pavement system. The Mr is defined as a ratio between deviatoric cyclic axial stress to the recoverable axial strain. In general, the Mr is measured through the cyclic triaxial compression test. Besides, other tests such as light weight deflectometer (LWD) and dynamic cone penetrometer (DCP) were also employed to calculate the Mr of subgrade soil. In this study, two types of soil in Vietnam were taken and used for determining the Mr in the laboratory. Two field tests (i.e LWD and DCP) were also implemented for comparison. The results of this study show that the Mr of soil was positively related to compaction degree and confining pressure regardless of soil type. However, the changes of the Mrs under different deviator stresses varied with the type of subgrade soil. The Mr increased with the greater deviator stress for the two types of soil. Furthermore, the field LWD testing method can be effectively utilized to determine the resilient moduli of soil samples tested under similar conditions with a high level of accuracy. Finally, it was found that the dynamic penetration index has a good relationship with the dynamic deformation modulus. This correlation may thus yield a satisfactory estimation with an appropriate coefficient of determination.