Seasonal Infiltration Behavior in Highway Slope made of Expansive Yazoo Clay

Expansive Yazoo clay soil is susceptible to volumetric deformation and is dominant in central Mississippi and other neighboring southern states of the United States. Due to recurring shrink-swell behavior, it causes a significant problem to the infrastructures in the area. Although Yazoo clay causes a significant problem in the deep southern states, limited study has been conducted to evaluate the infiltration behavior of Yazoo clay at field scale. The objective of this current study is to investigate the variation of seasonal infiltration behavior on highway slopes made of Yazoo clay. In this study, three highway slopes in Jackson metroplex were considered as referenced slopes. These highway slope sites were extensively instrumented using moisture sensors, water potential probes, rain gauges, air temperature sensors and soil temperature sensor. At each highway slope, sensors installed at three different depths (1.5 m, 3m, and 4.5 m) at the crest, middle, and toe of the slope. All the sensors are collected with automatic dataloggers to collect data at every hour. The field monitoring data were analyzed to investigate the infiltration behavior on Fall, Spring and Summer. The filed monitoring data indicated that the highest infiltration occurred at crest of the slope, and the moisture variation zone continues up to 3 m. Moreover, shrinkage cracks exist at the expansive Yazoo clay during the summer time with the soil temperature higher than 95 deg F. Due to the presence of the shrinkage cracks, the infiltration is significant on early fall. Once the rainwater infiltrates, it mostly retains within 1.5 m to 4.5 m depth of the slopes.