Data Based Real Time Moisture Modeling in Unsaturated Expansive Subgrade

Pavements constructed over expansive subgrade often experience volumetric deformation due to seasonal moisture fluctuation. In addition to causing shrinkage and swelling in expansive subgrade, moisture variation alters resilient modulus, permeability, and shear strength of soil, which ultimately affects pavement performance. Monitoring the real-time variation of moisture underneath pavement can enhance the understanding of moisture patterns, which can be useful in improving the serviceability of pavement. The objective of this paper is to develop moisture variation model based on real-time monitoring data due to precipitation. A two-lane state highway in Ellis County, TX was selected for field monitoring and data acquisition. Moisture sensors were installed at different depths up to 4.5 m. The soil was found to be high plastic clay in the selected site. Based on 2 years of monitoring, the amplitude of moisture variation ranged from 1 to 14% from the existing moisture content due to rainfall. Collected data were analyzed in a non-parametric environment for temporal variation to develop real-time model development. The developed model can be used to determine the moisture fluctuation within similar pavement subgrade due to rainfall events.