Assessing the Influence of Some Soil–Reinforcement Interaction Parameters on the Performance of a Low Fill on Compressible Subgrade. Part I: Fill Performance and Relevance of Interaction Parameters

Abstract

Soil–geosynthetic interaction is a complex subject, particularly in geogrid reinforced structures. Geosynthetic reinforcement can be used to improve the performance of granular layers on compressible subgrades in situations such as paved and unpaved roads and in reinforced foundations. This paper presents results of large scale cyclic loading tests on reinforced and unreinforced granular layers on a compressible subgrade. A woven geotextile and different geogrids were used as reinforcement. The geogrids were chosen aiming at achieving a wide range of values of some physical and mechanical properties to allow the investigation of the influence of some relevant properties related to soil–reinforcement interaction on the geogrid performance. The results obtained showed that geogrid reinforcement tensile stiffness and some of its physical properties such as aperture–fill particle diameter ratio, thickness and fraction of grid area available for bearing are important properties for grid performance as reinforcement in granular layers. A dimensionless parameter taking into account several geogrid properties has been introduced and shows good correlation with test results. On the other hand, no correlation was noted between geogrid aperture stability modulus and granular layer performance for the conditions of the tests carried out. The results show that a geogrid reinforcement should not be specified based only on its tensile stiffness and strength, since other properties play important roles in the gravel layer performance. This is particularly relevant for reinforced unpaved roads and railway tracks.