Finite element analysis of bearing capacity and cracking failure in semi-flexible pavement materials

Abstract Semi-flexible pavement (SFP) materials are known for their outstanding rutting resistance; however, their applications to new pavements are limited due to uncertainties in their structural bearing capacity and cracking behavior. In this respect, the structural performance and meso-scale cracking failure of semi-flexible pavement material have been investigated through a finite element analysis. A three-dimensional pavement model has been developed to investigate the influence of the SFP layer thickness, its placing position, and material modulus on bearing capacity. Meanwhile, a two-dimensional microstructure model, which is reconstructed from computed tomography scanning, is used to simulate indirect tensile tests and crack propagation within the specimens. The results show that by increasing SFP thickness from 4 cm to 18 cm, the vertical displacement reduced by about 32%, and most of the shear stress was confined to the near-surface layer, which enhances the rutting resistance significantly. It is noted that aggregate gradation and distribution are crucial for cracking resistance; specimens with finely graded aggregate showed more tortuous crack paths and superior post-peak ductility compared to those with low aggregate content and weak interlocking. The subgrade modulus variation has been found to have a decisive role in the total vertical displacement; when it decreased from 60 MPa to 40 MPa, there was a 16.7% increase in vertical displacement.