Forensic Investigation of Pavement Distortions Using Soil Suction

Abstract

State Highway 6 in Brazos County, Tex., is experiencing significant changes in surface profile at several locations. The changes in surface profile were noticed within a few months after construction. They quickly became severe enough to adversely affect vehicle safety. The longitudinal distance between the peak of the undulations is usually greater than 30 m. Patching to maintain a reasonably safe surface profile has been performed at least annually since construction. Routine site investigations prior to construction did not reveal underlying soil conditions that could produce these kinds of pavement distresses that appeared relatively soon after the pavement subgrade was stabilized with lime. In this study, the area was investigated using soil suction profiles to determine the origin(s) of the pavement distresses manifested at the surface. Findings indicated the swells were not caused by lime stabilization of sulfate bearing soils but were the result of surface water flowing through deep cracks and/or permeable soil layers to highly plastic expansive clays. Researchers used soil suction profiles to analyze the problem and recommended remedial measures to reduce subsequent swelling.