Mechanics Analysis of Composite Base Asphalt Pavement Structural base on Two Stages Design Method of French Norms
In this paper,mechanical response indexes are selected by referring to the two stages design method of French Norms and the common damage modes of composite base asphalt pavements.The three-dimensional model of the composite base asphalt pavement of the MBOUR-KAOLACK(MK)highway in Senegal is established by using finite element software.Then the differences in the mechanical response of the pavement structure under two stages(before and after the damage of the semi-rigid subbase)are analyzed.The influence of pavement structural layer thickness and modulus on each mechanical index is explored,and then the sensitivity of each index to the pavement structural layer parameters is analyzed.The results show that in the first stage,the tensile stain at the bottom of asphalt layer is much lower than the limit fatigue value.In the second stage,the tensile strain at the bottom of asphalt layer increases significantly,so the fatigue cracking index of the pavement should be selected depending on the semi-rigid subbase state.Among the two stages,there are large differences in all indicators except for the compressive stress at the top of asphalt layer.The tensile stress of semi-rigid subbase decreases with the increase of the thickness of each pavement course and the modulus of the asphalt course,but increases with the increase of the modulus of subbase,so the modulus of the subbase should not be too high.The tensile strain at the bottom of asphalt layer and compressive strain at the top of subgrade decrease with the increase of the thickness and modulus of the pavement layer.In addition,the compressive stress at the top of asphalt layer and the maximum shear stress of asphalt layer are less sensitive to the pavement layer parameters compared with the tensile stress at the bottom of semi-rigid subbase,the bottom of asphalt layer,and compressive strain at the top of subgrade.It is worth noting that the sensitivity coefficients of base and subbase thickness are the maximum for the fatigue index in the two stages,which shows that the values of base and subbase thickness are very critical in the design of composite base asphalt pavements.
road engineeringcomposite base asphalt pavementfinite element analysispavement structural parameters
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