Contribution à l'étude du comportement en fatigue des enrobés bitumineux - Etude de l'allongement des éprouvettes comme manifestation de l'endommagement diffus - Expérimentation - Modélisation

摘要

Fatigue tests of bituminous materials performed on trapezoidal specimens induce a loss of stiffness, combined with a significant extension of the specimens at the beginning of the test when applying high strain levels. This thesis presents the development of a visco-elastic constitutive law with unilateral damage for asphalt materials , based on the observation of tensile tests on asphalt binder films between two metal spheres. The unilateral damage is defined as the opening of the micro-cracks in the bitumen during extension and their closing during contraction. When put into a semi-analytical structural model of the trapezoidal specimen, this constitutive law leads to results close to those highlighted at the beginning of fatigue experiments for various experimental conditions (temperature, load frequency and strain amplitude level). According to the used modelling, the damage evolution law describes the fast initial homogeneous creation of the micro-cracks and then their slow development. The modelling is also able to explain a given percentage of the loss of stiffness. These results show mainly that the bituminous material extension is due to the asymmetric behaviour induced by the unilateral damage coupled with visco-elasticity. Therefore the asphalt mix extension is a way to quantify the level of the material damage.