Advanced Modelling for Rigid Pavement Assessment Using HWD

Abstract

Armed with its experience of the flexible airfield pavement testing for which an advanced dynamical method was developed and a technical guidance released in 2014, STAC took on the challenge of transposing the methodology to rigid pavements.The approach is the same as for flexible pavement: first the development of a mechanical model allowing calculating stresses and strains in the concrete slab under Heavy Weight Deflectometer (HWD) impulse loading, which can be used in a backcalculation process, and then the implementation of damage prediction laws.The developed mechanical model is based on a 3D finite element (FE) technique. It enables considering either static or dynamical impulse HWD loading, applied on the concrete slab center, slab edge, or slab corner, for an isolated slab.A thermo-mechanical model is included in the FE model and enables computing the slab deformation as a function of the thermal gradient in the slab. The resulting deformation can be used as initial geometrical input, as well as related internal stresses, for the above mechanical calculation.The numerical results have been compared with experimental data from HWD tests performed on the STAC's full-scale instrumented test facility. The latter comprises a 700 m2 rigid pavement including dowelled and non-dowelled areas. It is instrumented in the neighborhood of slab corners and middle of slab edges with sensors measuring vertical displacements on the loaded slab and the adjoining ones, and tensile strains at the bottom of the slab. An HWD survey was conducted on both dowelled and non-dowelled areas, including multi-height tests at different positions on the instrumented slabs.This paper first describes the dynamical 3D FE modeling developed, and the numerical results obtained. Then, the results of the full-scale validation are presented, which include comparison between expected surface deflections and HWD measurements, and comparison between predicted strain values and those recorded by embedded sensors.