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.

在这项研究中，基于粘弹性有限元（FE）分析研究了自上而下裂纹（TDC）的传播机理。通过3D FE粘弹性分析计算J积分，在具有水泥处理基层（CTB）和颗粒基层（GB）以及不同沥青混凝土（AC）厚度的路面结构中研究了TDC传播机理。结果表明，由于混合模式的I + II断裂，施加实际的轮胎-路面接触应力会使TDC的传播速率提高1.15到5.45倍。但是，拉伸和剪切模式的比例受TDC深度的影响很大。此外，通过将温度从25°C升高到50°C，J积分在不同深度下增加了3.5到4.4倍。由于车速从96 km / h降低到8 km / h，并且在低速时产生粘弹性冲击，