Assessing the Mechanical Response of Pavements During and After Flooding

Flooding is recognized as a catastrophic event and a threat to the load carrying capacity of pavements around the world. In the aftermath of flooding, the pavement structure could be inundated and fully saturated. The significant increase of water within pavement layers may cause weakness and induce damage with traffic loading, subsequently increasing maintenance costs and shortening pavement service life. The assessment of the structural performance and capacity of flooded pavements remains complicated due to lack of structural data immediately following flooding, and information about the pavement structure and materials is not always readily available. Currently, the decision to open roads for traffic is based on the assessment of the pavements, which relies on visual inspection and experience. An incorrect assessment of the flooded pavement structural capacity due to unforeseen conditions may lead to unexpected outcomes or failure. The objective of this dissertation is to advance the current knowledge of the behavior of flooded pavements, based on their performance properties and structural capacities. Several methodologies have been developed and examined for a set of pavement structures with different material types using layered elastic analysis to (1) investigate the pavement response to traffic loads under different moisture conditions, (2) identify the important parameters that affect the performance of inundated pavements, (3) investigate the influence depth of the subsurface water level at which the road can withstand traffic with zero to minimum deterioration, (4) estimate the in-situ pavement surface deflection, and (5) identify the catastrophic failure of pavements in post-flood events. The findings showed a significant reduction in structural capacity when the pavement structure was in the fully saturated condition, but the road could regain its capacity after desaturation and recession of water level. The influence depth for the subsurface water level was found to be dependent on pavement structure and material type. The most accurate method to estimate the in-situ measured deflection is to divide the soil layer into several layers in the layered elastic analysis. Accurate layer thicknesses, traffic type, and interlayer bond condition are the important factors for evaluating changes in expected horizontal strain at the bottom of asphalt layer, used for predicting fatigue cracking pavement performance. The type of base and subgrade materials are the most important factors for evaluating the changes in expected vertical strain at the top of subgrade layer, used to predict pavement rutting performance. This dissertation provides information to agencies that will enhance their understanding of the performance and structural capacity of pavements in post-flood events