Subgrade Stabilisation with Geotextiles

Subgrade stabilisation is the largest single application for geotextiles by volume. As environmental and population pressures become more severe, infrastructure projects will be directed further towards locations where ground conditions are marginal. This trend, in addition to the cost-benefit of geotextiles, is likely to result in increased usage of geotextiles. There are two fundamental aspects of design when geotextiles are used for subgrade stabilisation: the required thickness and quality of pavement materials to be placed above the geotextile; and the required properties of the geotextile. The thickness and quality of pavement materials is dependent upon the level of serviceability required of the completed pavement structure. The required geotextile properties are dependent upon the strength of the subgrade, the particle size of the granular layer above the geotextile, and groundwater conditions. Currently, selection of the appropriate geotextile properties for subgrade stabilisation is most commonly performed by a combination of empirical classification and design. The various procedures adopted in the selection of appropriate geotextile properties are highlighted in this paper.