Research on dynamic stress and excess pore water pressure of asphalt pavement under hydraulic-mechanical coupling

The impact of the initial static stress field on dynamic calculation results was considered, a three-dimensional refined coupling system model was constructed using finite element software, and the time domain and space domain distribution laws of dynamic stress and excess pore water pressure of saturated asphalt pavement under moving load were investigated.The findings show that the influence of the initial static stress field on the pavement dynamic calculation results will increase as the pavement depth increases. On the bottom surface of the upper layer, when the initial static stress field is not considered, the errors in vertical dynamic stress and excess pore water pressure are 29.6% and 30.8% respectively. As compared to dry pavement, the tensile stress on saturated asphalt pavement increases, and the stress attenuation rate slows when the load passes, putting the pavement structure in an undesirable situation. The negative peak value of the hydrodynamic pressure in the higher layer drops linearly as the permeability coefficient of the upper layer increases. In contrast, the negative peaking of the vertical dynamic stress grows linearly. Under the situation of potholes, the dynamic stress components in six directions of the saturated asphalt pavement all rise dramatically. Among the three shear stress components, τ_yz increases the most under the condition of pavement pothole, which is 345% higher than that without pothole. Among the three normal stress components, the vertical dynamic stress has the largest increase, which is 156% higher than that without potholes, and the increase in shear failure of the pavement is greater than that of tensile failure. The research findings will be helpful in determining the degradation process of saturated asphalt pavement and in designing asphalt pavement structures in rainy areas.