Evaluating Characteristics of Cyclic Plastic Strain Accumulation of Unbound Granular Materials Subject to Moving Wheel Loads

Abstract

Cyclic plastic strain behavior of unbound granular materials (UGMs) exhibits significant stress path dependency. Using a customized triaxial apparatus capable of applying stress path loading, a series of laboratory repeated load triaxial (RLT) tests were conducted on two typical UGMs through simultaneously varying the axial stress and the radial stress. Effects of realistic in-situ stress paths due to a passing wheel on cyclic plastic strain behavior of unbound granular base and subbase materials were investigated and quantified. The analysis of experimental results revealed that the accumulated plastic strain responses of both UGMs subjected to different stress path loadings can be described by the shakedown approach. The shakedown ranges of different stress path loads were classified for both materials. Finally, the significance of the findings made in pavement design practices was highlighted to evaluate permanent deformation resistance of UGMs and their suitability for use in pavement foundation layers.