Coupled Viscoelastic–Viscoplastic–Damage Modelling for Structural Optimisation of Prefabricated Plastic Pavement

The aim in this work is to evaluate and compare the mechanical responses of an unbound base pavement structure with prefabricated plastic modules as the surface layer, with the specific objective of optimising the structural designs of prefabricated plastic pavement through coupled viscoelastic–viscoplastic–damage finite element modelling. Two dimensions and six types of cross-section profile were designed and finite element modelling of pavement mechanical responses was conducted. A viscoelastic–viscoplastic–damage constitutive model was validated via experimental results and implemented in the finite element modelling for the prefabricated plastic modules. The von Mises stress, equivalent viscoplastic strain, and damage conditions were compared to highlight the performance enhancement obtained by optimising the modular designs. Results indicate that higher stress and larger viscoplastic deformation are found on the top half of the prefabricated plastic module, owing to the existence of a hollow structure and its relatively low modulus. The use of a small module size (20 cm in width) can largely improve the overall stress states and damage resistance. Moreover, adding supports can effectively optimise the stress distribution and constrain the high viscoplastic strain and damage areas to the supports and the joints. Based on the findings, it is concluded that further treatments and reinforcements on the supports and joints can make the prefabricated plastic pavement more resistant to vehicle loads.