Abstract
Abstract
The type of materials such as subgrade, subbase and base has a great effect on the quality and life of pavement. The nature of subgrade soil has the most important effect among other materials. There is a real concern in construction flexible pavements over a weak subgrade and the California bearing ratio (CBR) is very low for such soils. Therefore, the constructed pavements for such cases require more thickness. In fact, there is a need to look for economic methods in order to replace the lack of suitable construction materials for pavements such as subbase and base materials. This work studies the effect of geogrid reinforcement on CBR of subgrade soil and total pavement thickness. The soft sand soil from Al-Najaf city and one type of geogrid have been selected. It has been found that there is a significant improvement in CBR of subgrade resulting from geogrid reinforcement. The results indicated that the value of CBR was about 2.14% without using geogrid whereas this value was 12.84% in case of putting geogrid at 0.2H from the top of the specimen. Also, the reinforcement of subgrade with geogrid at 0.2 from the subgrade layer thickness will reduce the total pavement thickness by (30-40) %. Then, the same case study has been modeled using Plaxis (3D) software which is a finite element package. This package is equipped with specific features to deal with different complex cases and structures to simulate a realistic of case under study. The encouraging results have been obtained.
