An Approach in Evaluating of Flexible Pavement In Permanent Deformation OF Paved AND Unpaved Roads Over Sand Dunes Subgrade Under Repeated Loads

Abstract

Thickness of flexible pavement play very important factor in cost of construction of road ,in this study effect of change thickness of pavement on rutting of road is investigated . Two approaches are adopted; the first is the laboratory tests through simulation of three layers of paved road and two layers for unpaved road, using a steel box with dimensions of 600mm length 500mm width and 400mm depth. Sand dunes are used as a subgrade layer to investigate its behavior by using it as a part of flexible pavement structure under repeated load at relative density 55.7%. The effect of change in thickness of asphalt layer in permanent deformation is also investigated, through using three models at three different thicknesses, starting from zero (unpaved), 50mm and 100 mm. The second approach is the development of a three-dimensional finite element model for flexible pavements using ABAQUS (6.12-3) to simulate the laboratory test The results indicate that increase in the thickness of flexible pavement to 50mm from zero (unpaved), increases the number of passes about 971.42%, while the increase of thickness from 50mm to 100 mm, increases the number of passes by 517.33%. The results of ABAQUS program are very close to results of laboratory tests.

Keywords: Sand Dunes subgrade, Thickness of Flexible Pavement, ABAQUS   Models