Thermomechanical behaviour of bituminous layers containing rigid inserts for eRoads

• Autor(a) principal: Alves, Talita de Freitas
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/3/3138/tde-19012023-092333/
• topic: Correlação digital de imagens; Digital image correlation; Electrified roads; Finite elements method; Método de Elementos Finitos; Misturas betuminosas; Rodovias eletrificadas; Viscoelasticidade; Viscoelasticity

In general, four factors need to be accurately and simply accounted for on the design of flexible pavements: traffic and loading, environmental conditions, materials properties and failure criteria. The inclusion of charge-while-drive technologies inside road infrastructures modifies not only the common disposal of layers, but also the overall response of the structure to thermal and mechanical loadings. In order to quantify the impact of these inclusions on the performance of flexible pavements, this study proposes both numerical and experimental methodologies to measure temperature, stress and strain evolutions within electrified roads (eRoads). By means of transient 2-D FEM thermo-viscoelastic simulations, traditional and electrified road profiles were subjected to daily temperature fluctuations and to traffic. The eRoad studied contains electrified rails embedded in the bituminous wearing course, a case of particular interest due to its direct exposure to traffic and climate. The response of the structures was analysed and compared to admissible values commonly assessed to predict distresses: the vertical compressive strain on the top of the subgrade (permanent deformation) and the horizontal tensile strain at the bottom of the bituminous layer (fatigue life). The rigid inserts were found to affect the temperature distribution inside the layers. The repeated volumetric variations of each component due to temperature fluctuations generated strain in the bituminous layer, in magnitudes that can lead to premature failure and cracking. In laboratory, a thermal test was proposed to evaluate eRoad specimens undergoing warm and cold cycles by means of Digital Image Correlation (DIC) technique. The application of the DIC technique to obtain the contraction/expansion thermal coefficients of the materials is considered accurate and reliable, although some boundary conditions of the test might need improvements to minimize external sources of deformation and background noise. The strain fields measured numerically and experimentally lead to the same conclusion: the rigid inserts generate additional strain along the interface of the charging unit and the bituminous layer solely due to daily temperature fluctuations. The thermosviscoelastic model proposed and the experimental set-up have a great potential to assess innovative pavement profiles (inductive and conductive eRoads).