The study aimed to fundamentally understand how soil strength and hydraulic properties are impacted by recurring cycles of wetting and drying induced by climate variability, with the practical implication of forecasting the stability of highway embankment slopes. The review of literature on the effects of long-term cyclic wetting-drying phases on hydro-mechanical properties of clayey soils suggests that only a few cycles of wetting and drying can impact the strength and hydraulic conductivity, where the latter can increase several orders of magnitude. Laboratory model-scale experiments of Louisiana and Texas soils are still ongoing and will relate the laboratory test results to weathering cycles by accounting for parameters such as rainfall intensity and duration, evapotranspiration, temperature, and relative humidity. The objective of the laboratory testing was to determine the strength and unsaturated soil properties of samples collected from laboratory model-scale experiments and to investigate the subsequent changes in the hydro-mechanical properties of those clayey soils. For example, shrinkage test results provided a measure of the propensity and extent of strength loss incurred by a soil specimen when exposed to weathering cycles. Numerical modeling of highway embankments with material properties and test results obtained from lab testing were used to predict the factor of safety for an embankment in Texas.

Tran-SET Project No. 18GTLSU06