Pavement Design Using Unsaturated Soil Technology
Principal Investigator:
Satish Gupta, Professor, Soil, Water & Climate
Project Summary:
Pavements are constructed on compacted soils that are typically unsaturated with degrees of saturation varying from 75% to 90%. The negative pore-water pressure (soil suction) due to the ingress of water in between soil particles has a significant effect on material modulus. Several design and maintenance measures are undertaken to maintain unsaturated conditions in the pavement because they provide favorable engineering soil properties such as appropraite permeability and high shear strength. However, the conventional procedures for pavement design are often based on empirical procedures and not on unsaturated soil mechanics principles. Empirical procedures are used because pavement design procedures preceded the development of unsaturated soil mechanics. Fredlund and Rahardjo (1993) have proposed a theoretical framework for interpreting the engineering behavior of unsaturated soils. However, limited studies have been reported that extend these principles towards the designs of pavements. The goal of this project is to develop a pavement design method that is consistent with Mn/DOT and AASHTO mechanistic-empirical design framework but is based on the principles of unsaturated soil mechanics. Specifically, we propose to predict shear strength and modulus of unbound pavement materials using index tests, soil water characteristics curves, and simple mechanical tests. We also plan to provide comparisons between predicted properties and experimental results for the range of suction expected in-situ.
Sponsor:
Project Details:
- Start date: 02/2004
- Project Status: Completed
- Research Area: Infrastructure
- Topics: Pavements