Shear Behaviour of Geogrid-Reinforced Subbase Layer over a Stable Subgrade

Abstract

Geogrids are extensively used in pavement engineering to enhance the load-bearing capacity of subgrade soils and to provide a stable working platform. The primary purpose of this research is to evaluate the shear behaviour of geogrids with different aperture sizes and the tensile strength in stabilising a stable subgrade and reinforcing the subbase granular layer. A series of large-scale direct shear tests was performed on a subbase-subgrade interface with and without geogrids of varying tensile strengths under normal stresses of 20 kPa, 40 kPa, and 80 kPa. The improvement of various types of geogrids was quantified in terms of shear strength parameters, i.e., apparent cohesion (ca), internal friction angle (ϕ) without geogrid, and interface friction angle (δ) with geogrid. The improvements in shear strength parameters are demonstrated as the percentage increase in the interface friction angle and apparent cohesion relative to the unreinforced condition. The findings provide insights into the shear behaviour of various geogrid types, contributing to the optimization of geosynthetic-reinforced pavement systems.