Effects of water content on resilient modulus of a granular material with high fines content

The granular materials with high fines content are commonly adopted as the fill materials in the substructures of pavement and railway. The high-fraction fines may exist at the construction stage or accumulate gradually during the service life of transport infrastructures. Very few studies have been conducted on the resilient behaviour of granular materials with high fines content, especially when the changing water content is considered. In this study, three saturated cyclic triaxial tests with step-wisely increasing cyclic deviator stress were performed to determine the required reasonable cycle number for determining a stabilized resilient modulus. A new parameter, termed as “representative cycle number”, was newly defined to distinguish the unstable and stable periods of the deformation of the testing material under cyclic loading. The test data from this study and previous literature proved that the resilient modulus starts to level off when cycle number reaches “representative cycle number”. Furthermore, a series of cyclic triaxial tests with various water contents were conducted on a granular material with high fines content. The results indicated that the resilient modulus of the granular materials with high fines content would drop firstly with the increasing cyclic deviator stress and then turned to increase gradually. The level of cyclic deviator stress at which resilient modulus started to rise increases with the increase of water content of the specimen. Lastly, a modified prediction model is proposed, considering the effects of water content and stress paths, to capture the non-monotonic relationship between resilient modulus and stress state.