Effect of Suction History on the Small Strain Response of a Dynamically Compacted Soil

Ana Heitor, Buddhima Indraratna and Cholachat Rujikiatkamjorn

Small strain behaviour is a key indicator in the assessment of the performance of compacted fills. Compaction conditions i.e. initial moisture content and applied energy, govern compaction effectiveness and thus the structure and matric suction of compacted soil. During the service life of earth structures, they experience changes in hydraulic behaviour owing to climatic changes. While the results of previous research studies indicate that the effect of changes in suction on the dynamic response is significant, only limited research has been engaged in the assessment of the effect of post-compacted changes in suction induced by periods of intensive precipitation (i.e. wetting) and drought (i.e. drying). The seasonal fluctuations of moisture reflected in the soil’s suction history have an important impact on the geomechanical performance of compacted soil.

In this paper, the aspects related to the effect of suction history of a compacted silty sand soil subjected to cycles of wetting and drying are described. The results not only confirm the importance of the recent suction ratio (or CSR) in governing the mechanical response at small strain but also suggest that subsequent wetting-drying cycles further induce hysteretic changes, particularly when following the wetting paths.