Investigation of Crack Propagation in Asphalt Pavement Based on APT Result and LEFM Analysis

摘要

When reinforcing existing cracked asphalt pavements, the design and evaluation of thedurability of the reinforced structure are quite different from those of a new pavement generallybased on fatigue criteria deduced from stress and strain fields computed for the undamagedpavement. For the design of reinforcement solutions, the presence of cracks and theirpropagation must be considered explicitly. To move in this direction, the present article aims atimproving the understanding of bottom-up crack propagation in asphalt pavements. Someinvestigations relying on the interpretation of an accelerated full-scale fatigue test are presentedas well as the numerical analysis of this test through the theory of linear elastic fracturemechanics and the Paris law. The tested pavement section is composed of four layers. The twouppermost layers are made of asphalt concrete (AC) materials whose modulus and fatigueperformances are different. The pavement is subjected to repeated loads applied by theFatigue du Béton Armé Continu (FABAC) traffic simulator of the French Institute ofScience and Technology for Transport, Development and Networks (IFSTTAR), and the developmentof cracking in the AC layers is monitored using embedded instrumentation and FallingWeight Deflectometer (FWD) test campaigns. To better control the crack pattern that developsduring the fatigue test, an artificial flaw (metal angle) is purposely placed at the bottom ofthe AC layers (in the transverse direction to the moving loads) to localize the initiation of cracking.A bottom-up crack is supposed to grow vertically from this defect in the AC layers. This iseffectively detected and followed by the experimental measurements, which are combined tomodel for the analysis of the test. Finally, the kinetics of crack growth deduced from theAccelerated Pavement Test (APT) results and those computed using the Paris law calibratedfrom fatigue tests performed in the laboratory are compared.