LAUSR

ABSTRACT In this paper, a study is conducted on several realistic models that have been developed to represent the effects of thickness variations of asphalt mixtures with respect to the time- and rate-dependent behaviour of asphalt concrete. To predict the response, the theory of viscoelasticity is employed and the computational framework is implemented into a 3D multilayer model to use in finite element method. Three asphalt depths have been assumed and laid under repeated loading. The load passes are kept to 500 pulses. Study on the goodness of cycle numbers shows 200 pulses are good enough and the response has been converged before 200. The simulations show that viscoelastic behaviour is more sensitive to thickness variations, and the tensile strain and compressive stress under the asphalt reduces faster than conventional designing assumptions; however, the viscoelastic final response is still greater. The results reveal that the base course is greatly influenced by asphalt thickness variations so that a 10 cm viscoelastic overlay causes basecourse to bear stress eight times greater than that of elastic assumption. The resulting compressive stress above the subgrade is significantly affected by asphalt thickness and stress-induced history. Moreover, the results show that the viscoelastic behaviour develops the stress overlapping zone.