Analysis and Design of Flexible Pavements by Empirical Tools

Abstract

This paper falls into two parts. In the first part, the widely used analytical-empirical method of pavement design and evaluation is discussed and in the second part two simulation models are presented to predict the design of flexible pavement. Analytical results are compared with simulation models. There are differences between the assumptions on which the theoretical models are based, and the reality of pavement materials and structures, and these differences are important both for the determination of input values (elastic parameters) and for the calculation of pavement response. Linear elastic theory often results incorrect moduli, when used for back calculation of layer moduli from deflection testing, and in questionable stresses and strains, when used for forward calculation. Including non-linear materials characteristics may improve the theoretical model, but no theoretical model has yet been conclusively verified with experimental data. In the second part of the paper two theoretical models are presented. The first model is stochastic and considers the spatial variation of pavement materials, layer thickness and traffic loads as well as seasonal variations. The second model deals with the forces and displacements the individual grains in a particulate medium. The input to this model includes the grain size distribution, the shape of the grains and the degree of