A probabilistic approach for asphaltic pavements design in Brazil

Abstract

A deterministic approach is often used on roadway pavements design. The inherent variability to the relevant parameters of the construction and performance of a pavement is generally despised. However, it can be considered by using a probabilistic approach, where every single parameter is characterized by an adequate probabilistic distribution. The Brazilian design method preconized by DNIT determines the minimum granular material thickness to protect the subgrade. The granular material is converted on layer materials according to the different structural coefficient of each material. By selecting a thickness higher than the minimum required by the method, the result is a pavement structure with a higher probability of success. In other words, a higher thickness means a higher reliability level on the design process. The reliability level is considered on the AASHTO design method, where the structural number required must be increased due to the desired reliability. This paper proposes the use of the probabilistic approach on the asphaltic pavement design. The proposed model determines the reliability of a pavement structure design by comparing the predicted traffic during the analysis period and the allowable, both characterized by probabilistic distributions, calculated using Monte Carlo method. The reliability is determined for both design methods, DNIT and AASHTO. The conducted case study showed the influence of reliability in the structure design and its performance. Thus, by varying thicknesses of the layers is possible, using the proposed model, the calculation of reliability level, or the probability of success or failure, for the designed structure. © Copyright 2016 by Mairepav8 2016 Organizers.