Three-dimensional finite element analysis of top-down crack propagation in asphalt pavements

Abstract

In this study, the mechanisms of top-down crack (TDC) propagation were investigated based on viscoelastic finite element (FE) analyses. By computing J-integral through 3D FE viscoelastic analyses, TDC propagation mechanisms were examined in pavement structures with cement-treated base (CTB) and granular base (GB) and different asphalt concrete (AC) layer thicknesses. The results showed that applying realistic tire-pavement contact stresses caused TDCs propagation rate to increase 1.15 to 5.45 times due to mixed-mode I + II fracture. However, the proportion of tensile and shear modes was significantly affected by the TDC depths. In addition, by increasing temperature from 25 to 50 °C, J-integral increased 3.5 to 4.4 times at different depths. Due to vehicle speeds reduction from 96 to 8 km/h and viscoelastic impact at lower speeds, TDCs propagation rate increased up to 1.9 times in different depths analyzed.