Validation of the Austroads quasi nonlinear sublayering approach for the design of flexible pavements

摘要

It is well known that unbound coarse granular materials and fine-grained subgrade materials behave nonlinearly under the traffic loading. However, in mechanistic pavement design, it is common practice to model the coarse and finegrained materials as linear elastic materials, so that a simple set of parameters, in this case the elastic modulus and the Poisson ratio, can be used to represent each layer. The Australian mechanistic empirical design method (Austroads) uses a simplified approach to account for the nonlinear behaviour of the unbound coarse and fine-grained materials. In this paper, the Austroads quasi-nonlinear analysis is compared with the nonlinear analysis to examine the validity of this approach. The base-course materials and subgrade soils were modelled as isotropic and as cross anisotropic to examine the effect of this factor on the validity of the results. The Austroads quasi-nonlinear analysis provided better solutions than the linear elastic analysis without sublayering; however, it needs some adjustment to provide better match with the nonlinear analysis solution and, ultimately, with the actually measured values.