Three-Dimensional Model for Moisture and Volume Changes Prediction in Expansive Soils

A three-dimensional moisture diffusion and volume change model Suction heave (SUCH) is described. The model SUCH is capable of predicting soil moisture changes in terms of soil suction and the resulting volume changes (shrink/heave) in expansive soils under a covered area (e.g., flexible slab model) with respect to time when the supporting soil mass is subjected to different edge conditions that commonly cause moisture changes (e.g., climate, trees, ponded water). The moisture movement in unsaturated soils model was based on Mitchellʹs diffusion equation for soil suction and the volume changes (shrink/heave) calculation was based on Wrayʹs model. The model SUCH was validated against field data from four test sites in three countries (i.e., United States, Saudi Arabia, and Australia) with widely varying climatic and soil conditions. In each of these widely diverse sites, the moisture diffusion and volume change model SUCH was shown to be valid.