Evaluation of Geogrid-Reinforced Flexible Pavement System Based on Soft Subgrade Soils Under Cyclic Loading

Abstract

Geogrids have been successfully used to improve soft subgrade and reinforce weak base course by providing lateral confinement. However, Soft saturated fine-grained subgrade soils are distinguished by their high compressibility and low undrained shear strength. Moreover, when the stress is applied on the soft foundation soil resulting from repeated traffic load causing the soil particles to press together and the volume of the soil will decrease resulting in settlements. While applying stress on saturated soft foundation soil due to the increase of the water stress is squeezed out of the soft subsoil causing settlements. In this regard, geogrid reinforcement is the soil improvement technique which proposed to be used in this study to provide a solution for this problem. Using these techniques has been contributing to enhancing the pavement performance systems including the increase of the pavement service life. To simulate the above-mentioned situation, the experimental work included two models: raw materials model and geogrid model. A laboratory model tests are carried out to simulate the asphalt pavement layers and design cycling load system equivalent to the standard single axle load, which were prepared throughout a design and assembling of steel Container model. In this study, development of three-dimensional finite element models for flexible pavement system based on the numerical study has been carried out throughout the application of elastic model using ABAQUS software ver.6.14.4 to simulate and analyze the relationship between the number of applied load cycles and permanent displacement for the pavement layers of two model. The test results that recorded at 1600 cycle load, showed that the permanent displacement at the surface of pavement for improved models and compared with the raw material model has seen decreases by (7.75%). Also, by using the reinforced model is found to be more effective to resist vertical strain under cyclic load at the surface of subgrade soil if compared with the raw material model. Moreover. The results of ABAQUS program are very close to results of laboratory tests.

Keywords: Geo-Grid Reinforcement, Soft Subgrade, ABAQUS.