Finite Element Modelling for Rutting Prediction of Flexible Pavement Considering the Effects of Sub-grade Material Quality and Gradation of Aggregates

Abstract

Infrastructure facilities are delivered for economic growth of countries' progress. Road transport is the dominant mode of transport in developing countries like Ethiopia. Major types of distresses observed on major sections of the trunk roads is permanent deformation in the form of rutting. As the roads have experienced deterioration, which has given rise to the need for periodic maintenance and rehabilitation. Pavement deformation or rutting is one of the key distresses that affect the pavement performance. Performance of roads with regards to ride-ability and roughness is known to have a significant cost implication to the road users in terms of operational cost, in addition to affecting their safety and comfort. Aggregates are one of the key building materials used in the construction industry and the largest portion of an asphalt pavement. The general objective of this research is Investigating a modelling tool for rutting prediction of Flexible pavement considering effects of aggregate gradation and quality of sub grade material. Hence, in this study, a three-dimensional finite element model was developed, using ABAQUS software, to predict rutting on flexible pavement considering effect of Sub-grade material quality and gradation of aggregate. Flexible pavement modelling was performed using finite element method; a 3-D dimensional finite element model using ABAQUAS (ver.6.14-1) computer program was developed. The material in this model was assumed to be homogenous isotropic linear elastic materials. Natural subgrade materials were modeled in terms of the elastic modulus and Poisson’s ratios. The fine finite element mesh used in this study gives the values of stresses and strain in each point. The results of rutting prediction of existing flexible pavement and series of model created are discussed. According, to the modelling results the permanent deformation (rutting) severity are increase as the resilient modulus of the pavement materials is decrease. This thesis presented the static loading response of flexible pavement layers in terms of strain, stress and deflection. Besides, investigate the effects of different aggregate gradation and sub-grade material qualities. It was found that in the elastic domain, considering linearity of the material and stress dependency can significantly affect the critical responses of the pavement layers.