Impact of subgrade soils on pavement roughness

Abstract

To highlight the impact of subgrade soil variability on the pseudo-profile and roughness at the end of road construction, a research program has been carried out at the Laboratoire sur les chaussées et matériaux bitumineux at École de technologie supérieure (ÉTS). The analysis is intended to highlight the variability of materials’ characteristics according to the longitudinal and vertical axes of the road. The proposed approach aims to calculate potential settlement variations through a global numerical simulation of a road section, in a bid to identify the expected pseudo-profile and to quantify the roughness quality by calculating the international roughness index (IRI). The proposed methodology was tested at a new road construction project in Québec. Here, the results of the simulations are compared to the details of the actual pseudo-profile obtained at the end of road construction for the project under study. It is shown, through the finite difference modeling of the mechanical behavior of the subgrade soil (FLAC calculation code), that the long wavelength pseudo-profile of the road at the end of construction can be determined, and that it is strongly influenced by subgrade soil variability. This article presents a second analysis carried out by Vaillancourt and Perraton in 2015 as part of a study of the impact of subgrade soils on pavement roughness.