Moisture influence on structural responses of pavement on expansive soils

Abstract

Expansive soils are prone to heave and shrinkage due to changes in their natural moisture content. It would be helpful to predict distresses in pavement induced by heave/shrinkage because of long-term moisture variations in the subgrade considering specific environmental conditions. The virtual load method (VLM) has recently been developed to identify virtually distributed load that produces an equivalent deflection of the pavement caused by heave/shrinkage of expansive subgrade soils. In this research, a pavement section of interstate highway 220 (I-220) in Northern Louisiana is considered to implement the VLM and analyze structural behavior due to natural migration of water in unsaturated soil layers. Heave/shrinkage of the soils is computed from the predicted moisture content changes in subgrade using software VADOSE/W. In applying the Winkler’s model in the inverse theory to identify expansive soil-induced stresses in the pavement, a new iteration algorithm is proposed to consider the pavement-soil interaction. Special attention is drawn to the location of absolute maximum shear forces and bending moments in the pavement and their influences on the subgrade deformation. The effects of pavement stiffness and swelling pressure of the subgrade expansive soils are presented to understand the behavior of pavement on expansive soils.