Transient Analysis of Multilayered Poroelastic Flexible Pavements

Historically, the layered elastic method has been the preferred response model used in flexible pavement mechanistic-empirical methods in the pavements industry. Since this analytical procedure is restricted to linear elastic material behavior, important behavioral mechanisms driving performance such as temperature-load frequency dependency in asphalt or moisture sensitivity in unbound and subgrade layers are addressed either through modulus adjustments outside the response model or empirically in a permanent deformation model (or both). This paper provides the analytical solution to the Biot poroelastic boundary value problem for an axisymmetric multilayered system under surface loads. The Laplace-Hankel transform method is used to resolve the time and spatial partial differential equations. The inverse Laplace transform is performed using Schapery’s direct method, while the inverse Hankel transform is conducted using Gauss-Legendre quadrature. In addition to conventional formulations solving the transient consolidation problem using fully-bonded interface conditions, an interface frictional model capable of simulating partial and unbonded conditions is also presented. Interface fluid flow conditions for both continuous flow and no flow boundaries are presented. Comparisons are made to published results to verify computed responses. Results show that the model matches well with published data. Findings suggest that the proposed solution could provide improved mechanistic responses for estimating the effects of moisture sensitivity on the performance of flexible pavement structures.