Quasi-Static Response Analysis of Viscoelastic Flexible Pavement using Differential Quadrature Element Method

Analysis of road pavements responses such displacements, strains and stresses resulting from imposed impulsive loads, is one of the most important issues in pavement design. Various methods such as finite element, boundary element etc. can be used for analysis of this problem, but, as in all matters, the main goal is to reach high accuracy while spending less time for analysis, in this research, a new method of differential quadrature method (DQM) is used. In most studies implemented to date, the behavior of flexible pavement is considered as an elastic material but the asphalt concrte (AC) layer on top of the flexible pavement, behave as a viscoelastic material. The theory of viscoelasticity is an old subject, but its application in flexible pavement modeling, due to the time-dependent behavior of the viscoelastic materials and also the layered structure of flexible pavement, complicates the modeling.
In this paper, first, with incremental integration of Boltzmann's correspondence principle and using the generalized Wiechert model for viscoelastic behavior, incremental equilibrium equations of 3D axisymmetric condition are obtained and discritized in spatial domains using DQM. Then, in order to verificate, three-dimensional multilayered viscoelastic problems are modeled using Differential Quadrature Element method (DQEM), and the results of this method are compared with analytical solutions and finite element method (ABAQUS software) results. In the end, a flexible pavement structure with viscoelastic behavior under sinusoidal loading is simulated quasi-statically, and the effects of the viscoelastic response of the pavement under loading with different speed of vehicles as well as several performance indicators such as tensile stress and tensile strain under the AC layer, vertical stress on the subgrade, and vertical displacement of the pavement surface, which are commonly used in the design of the pavement, are investigated