Behavior of Unsaturated Silty Soil Due to Change in Water Content and Suction

To reduce and mitigate rainfall-induced problems, there is a need to improve understanding of the failure mechanism of unsaturated soil due to changes in water content in the soil body. Natural slopes, man-made slopes and embankments are generally made of unsaturated soils. In this regard, the objective of this study is to investigate the behavior of unsaturated silty soil due to change in water content and suction. The change in the water content of the sample represents the effect of rainfall. Moreover, this study aimed at understanding the effect of the degree of compaction on the strength and deformation characteristics of unsaturated silty soil. In the experiments, two series of laboratory element tests on double-cell triaxial machine carried out on DL clay (silty soil) in which water content varied from dry to wet of optimum moisture content, and the degree of compaction varied to study the effect at diverse overburden pressures. The test series is conducted in constant water content condition, and the measurements are closely monitored throughout the test course (initial suction to shear) to observe the changes in effective stress. The observed changes in the parameters are also presented in three dimensions to show the behavior of soil under the influence of more than two parameters. From this research, it is examined that with the increase in degree of compaction, volume change behavior transformed from compressive to dilative. Moreover, the strength of the silty soil increased with the increase in suction, i.e., due to decrease in water content, and vice versa.