Authors
Building & Construction Engineering Department, University of Technology/Baghdad
Abstract
One of the major sources of distress in roads is the cracks that appear in flexible asphalt pavements. Combined wheel and thermal load induced cracking in the form of bottom-up and top-down fatigue cracking.
In this paper, combined effect of wheel loads and temperature is considered in finite element analysis of flexible pavement layers. The heat flow equations are derived and the program (ANSYS V 5.4) is utilized to carry out the analysis. The subgrade layer is modeled as an elasto-plastic material following Drucke–rPrager model for yielding of the isotropic material, while both the asphalt and base layers are
considered elastic. Three different thicknesses for the asphalt layer are tried; namely, 0.05 m, 0.10 m and 0.15 m, respectively. A temperature rise of 40 oC was considered in addition to wheel pressures.
It was found that an increase of wheel pressure from (500) to (700) kN/m2 leads to increase in vertical displacement of about (4 – 8)%. This increase becomes (10 – 22%) when the wheel pressure becomes 1000 kN/m2. The temperature rise leads to decrease in the effect of wheel pressure because temperature leads to expansion (upward movement) reverse to wheel load effect. The effect of wheel load is transmitted directly to the underlying subgrade within the wheel zone. The deformed zone under the wheel becomes larger when the load increases. The maximum displacement increases by about (24%) when the load is
duplicated.
Keywords
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