A New Approach to Estimate Bearing Capacity of Strip Footings on Geogrid-Stabilised Granular Layer over Clay

Abstract

In this study, the finite element method (FEM) is used to estimate the bearing capacity of strip footing on a non-stabilised and geogrid-stabilised granular layer over clay. The FEM model was developed using ABAQUS software that accommodates a range of angles of internal friction and thicknesses of overlying stronger granular layer and strength of underlying weaker clay layer. The results are used to develop design charts with dimensionless parameters in terms of linear-gradient (m) and the ratio of undrained shear strength of clay to effective vertical stress at the base of the granular layer ({{c}_{u}/p}_{0}). The proposed charts also contain trend lines with simple power-rule equations for different angles of internal friction of the granular layer. The charts are validated and compared with the published results in the literature and found to be closely similar. A design example is provided to illustrate the comparison of the design curves and to benchmark with other established design methods. The comparative results reveal that the proposed approach yields a comparable outcome and predicts reasonable bearing capacity. Moreover, the developed design charts and the associated equations are relatively simple and easy to use. A typical result of the analysis indicates that the use of a geogrid-stabilised granular layer provides a capacity improvement factor (CIF) of 1.1 to 1.6 depending on the soil parameters and the thickness of the granular layer.