ANALYSIS OF PAVEMENTS WITH GRANULAR BASES

Abstract

The nonlinear stress-strain response of unbound granular materials has to be modeled satisfactorily when numerical analysis is used for pavement structures that contain significant quantities of such material. The simple model, which has been used widely for the purpose of relating resilient modulus to the sum of the principal stresses, has serious limitations. This is because the triaxial tests used in its development do not cover an adequate range of stress paths when compared with the situation in the pavement. A more complex and accurate model is described that has been developed from extensive laboratory repeated load testing. It is expressed in terms of shear and volumetric stress-strain relationships. The need for better modeling of cohesive soils for analysis is also discussed and the importance of the principle of effective stress is emphasized. A new finite-element program is described and its main features are explained. It uses a secant modulus approach, has been specifically developed to deal with nonlinear materials, and is called SENOL for secant modulus nonlinear. The use of the new granular material models for the three-dimensional stress system in a pavement is discussed and results from analyses with SENOL are compared with in situ measurements from a test pavement. (Author)