• Future climate leads to shallower wetting depths in expansive soils. • Climate-informed inputs reduce design pier lengths in expansive soils. • Air temperature dominates subsurface moisture migration more than rainfall. • Deeper clay profiles are more sensitive to climate-driven changes in wetting. Climate change presents growing challenges for geotechnical engineering, particularly in expansive soils that are sensitive to climatic variations due to their shrink-swell behavior, which can damage foundations and superstructures. This study quantifies climate change effects on long-term subsurface moisture migration and assesses implications for drilled pier design. Finite element modeling, calibrated and validated with laboratory and field data from the TRACON building at Denver International Airport, was used to simulate long-term water migration. The validated model was applied to representative Colorado Front Range soil profiles and projected through 2100 using CMIP6 climate scenarios for SSP1-2.6 and SSP5-8.5. Compared with a traditional climate approach, projected scenarios produced slightly shallower wetting depths (4% for a shallow clay profile and 8% for a deeper clay profile). Although both SSPs produced similar reductions in wetting depth, the SSP5-8.5 scenario yielded a lower degree of saturation, indicating that climate change affects both depth and degree of wetting. Sensitivity analyses identified air temperature as the dominant control on water migration, followed by precipitation, whereas humidity, solar radiation, and wind speed exerted smaller and less consistent effects. Pier designs were evaluated using rigid and elastic methods incorporating climate-adjusted moisture profiles. Climate-informed inputs reduced pier lengths by approximately 3–6% using the rigid method, whereas the elastic method exhibited greater sensitivity, with reductions of about 5–12%. These findings highlight that, particularly for elastic pier design, the climate-informed depth and degree of wetting should be assessed jointly rather than relying solely on depth of wetting.
Chao et al. (Wed,) studied this question.