The swelling and shrinkage behavior of expansive subgrade in North Texas is affected by changes in soil water content as well as matric suction. As a relationship between moisture variation and pavement performance exists, estimation of moisture variation in the subgrade soil could quantify pavement deformations. The objective of the current research is to investigate the moisture and suction variation of pavement site due to real time climatic loading and predict these results with numerical modeling. For this study, two lane roads in Ellis County, TX was selected for data acquisition and monitoring. Soil moisture and suction sensors were installed up to 4.5 m depth to monitor in-situ moisture content, and rain gauges were installed to record the precipitation at the site. Soil water characteristics curve (SWCC) was estimated from both laboratory test and field datas, which was then incorporated into finite element (FE) software PLAXFlow for transient analysis. The FE results were compared with direct field measurements. The validity of the estimated parameters was confirmed, as FE results corresponded with direct field measurements. Analysis showed that change in suction at shallower depths recorded considerable variations. The study results indicated that FE modeling can provide effective information about the subgrade matric suction variation.
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