EFFECT OF SURFACE CRACKING ON RESPONSES OF FLEXIBLE PAVEMENTS STRUCTURE | ||
| JES. Journal of Engineering Sciences | ||
| Article 5, Volume 34, No 3, May and June 2006, Pages 699-717 PDF (369.34 K) | ||
| Document Type: Research Paper | ||
| DOI: 10.21608/jesaun.2006.110556 | ||
| Author | ||
| Hassan Y. Ahmed* | ||
| Associate Professor, Civil Engineering Department, Faculty of Engineering, Assiut University, Assiut, Egypt | ||
| Abstract | ||
| Pavement cracking is a major factor of failure in surface of pavements structure, In spit of this, seldom intention has been considered how is the pavement structure has been affected when surface cracking are presented and/or progressed. On the other hand, higher costs are presented for maintenance and repair. Generaly, pavement surface conditions in terms of pavement surface cracks, rutting, roughness and pit-holes are the main factors used to establish criteria for pavement maintenance and repair. Structural adequacy factor of the pavement is usualy neglected. The accurate decision making processes for maintenance and repair works must be done not only due to functional conditions, but also due to structural conditions. Finite element analysis is used in this research paper using the ANSYS-10 program. SOLID45, and SOLID185 elements represent unbounded layers, and asphalt cement layers respectively to evaluate the stresses in a flexible pavement system under different conditions. These conditions were: (1) The vertical load of a single wheel was modeled as uniform pressure placed directly at the edge of the transverse crack. (2) The effects of seasonal differentiation of the pavement material properties during winter and summer. and (3) Various crack depthes which represent 25% , 50%, 75% and 100% of the asphalt layer thicknesses are also, considered in the analysis. The horizontal normal stresses along the top and bottom of the AC layer, and vertical stresses at selected points in the base has been investigated. Comparisons of stresses finally were made for all studied cases. It is found that the presence of crack in the AC layer significantly increases both the vertical stresses and the horizontal stresses in the AC layer which indicate a greater potential for tensile stresses outside the tire treads than in the middle of the treads. With the wheel load located at the edge of transverse crack there is considerable change in the values of horizontal and vertical normal stresses in the asphalt pavement layers. Seasonal variation has significant effect on the normal stresses values, where the maximum horizontal tension stresses (σyy ) is higher in winter than that in summer with about 66%. Finally, it is recommended that at crack depth ratio (CDR) 50% pavement must be rehabilitated to prevent initiation of new cracks or rutting of asphalt pavement surface. In other side the winter season is considered the critical for initiation of cracking, as summer season is considered critical for rutting occurrence. | ||
| Keywords | ||
| Pavement Surface Cracking; Three dimensional finite element; Horizontal stresses; Vertical stresses | ||
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