Assessment of flooding-induced pavement subsurface moisture variation and structural damage using integrated hydro-mechanical modeling

Flooding poses a significant threat to pavement structures by increasing subsurface moisture content, which reduces the load-carrying capacity of subsurface materials. This study aims to assess flooding-induced variations in pavement subsurface moisture and quantify the associated structural damage using integrated hydro-mechanical modeling. Laboratory experiments were first conducted to investigate pavement subsurface moisture dynamics during saturation and recovery, accounting for the effects of soil type and extreme weather conditions. A hydrological model was then developed and validated to analyze subsurface moisture increase and recovery in two case studies subjected to realistic flooding scenarios, incorporating post-flooding groundwater recession and climate conditions. Based on the moisture variation results from the hydrological model, a mechanistic model was developed to calculate critical pavement responses during the recovery period when traffic was resumed and to quantify the resulted flooding damage. Laboratory results revealed that moisture dynamics within the pavement subsurface differ significantly from those in exposed soil. Pavement subsurface moisture showed a delayed response to extreme weather events and was less affected by atmospheric conditions during the recovery period. Instead, groundwater recession was found to be a major factor influencing moisture recovery beneath the pavement. Mechanistic analysis revealed that daily pavement damage fluctuates over time, regardless of subsurface moisture recovery, due to seasonal temperature variations that affect the asphalt layer modulus. This highlights the impact of flooding timing on pavement performance. Damage quantification further indicated that flooding has more pronounced impact on subgrade than on asphalt layer.