FINITE ELEMENT MODELING OF RUTTING FOR FLEXIBLE PAVEMENT

الملخص

The aim of this research is studying the effect of base and subgrade layer local materials properties on the rutting damage of flexible pavement due to repeated traffic loading. The most roads in Baghdad city present severe rutting damage due to absence of quality control in the construction of granular unbounded pavement layer. Furthermore many trucks with overweight using the roads and high temperature in summer produced distresses and deterioration of flexible pavement. Flexible pavement analyses are performed using finite element method; a 3-D dimensional finite element model using ABAQUS (ver. 6.12-1) computer program are developed. The results obtained for base layer show reduction in rutting damage by about (58%) while subgrade layer provided damage reduction only (10%). Also the critical value for vertical compressive stresses is (480 kPa) below the wheel loading area which is about (70.9%) of the applied tire pressure and then decreased gradually with depth to about (118 kPa) approximately (17%) of the applied tire pressure within the base layer and remains almost constant with depth through the subgrade layer. And for horizontal stresses a high value was observed on surface of flexible pavement under the path of wheel load rather than the compressive stresses then decreased laterally with horizontal distance.The local untreated base material experience critical rut depth of (8 mm) at 1000 number of repetitions and for treatment base materials the number of load repetitions to cause damage rutting increased (10) times to about 10000 number of load repetitions.