Numerical investigation of the effect of water content variations in expansive clay subgrades

ABSTRACT The research presented in this paper was focused on a numerical model predicting moisture content fluctuation in expansive subgrades. The model leads to a mechanism-based calculation of the vertical movement of a pavement sitting on expansive soils due to climate changes. The model was created using VADOSE/W in analysing changes in moisture content over a certain period of time, with climate and environmental effects take as imposed boundary and initial conditions. Moisture content fluctuations from the numerical analyses were validated by the long-term moisture content measurements below the pavement of country road FM-2 on the expansive Frelsburg clay near the city of College Station in Texas, U.S.A. VADSOSE/W was then applied to analyse the pavement of I-220 at Bossier Parish, Louisiana, U.S.A., which sits on subgrades of highly expansive Moreland clay in northern Louisiana. The numerical modelling was completed for a one-year period with input climatic and environmental data.