Investigation of the Effects of Geogrid Reinforcement in Flexible Asphalt Pavement Layers using Numerical analysis method: The case of Jimma to Sekoru road Corridor, South Western Ethiopia

Abstract

A flexible pavement is a load bearing structure, consisting of layers of different granular materials above the earth. There are factors that affect this structure, such as, increasing traffic intensity; high tire pressure, increasing axle loads, weak subgrade material, are causing early signs of distress on bituminous pavements throughout the world. The road segment of the study area is affected due to the presence of week subgrade material (existence of expansive soil) as well as the presence of shallow groundwater. Therefore, the study aims to conduct the effect of geogrid in flexible asphalt pavement using numerical analysis method. To achieve the objective of the study the following activities were conducted (i) survey of the pavement surface condition, (II) assessment of engineering properties of pavement layers, (iii) conducting pavement analysis by incorporating the effect of geogrid reinforcement on pavement layers by taking into consideration the influence of geogrid location and groundwater fluctuations. From site investigation, rutting and longitudinal crack was recorded as high sever condition on the section. From PLAXIS 2D analysis, significant improvement in pavement stabilization was observed using geogrid. The effectiveness of geogrid were obtained at the interface between subbase and base course, sub-base and sub-grade of pavement. As a result 10.29% reduction in total deformation was observed for road section having block cotton soil as subgrade when geogrid was reinforced between sub base and sub grade. But for road having red clay as subgrade soil, 9.13% total deformation reduction was observed with the same geogrid reinforcement. Comparatively a high deformation was observed when the ground water level was reached at subgrade surface and 33.33% increment was shown for road with block cotton soil at subgrade and 35.71% increment was also shown for road with red clay as subgrade. Therefore the geogrid material was effectively stabilize the pavement layers