The bearing capacity of a square footing on an unstabilised and geogrid-stabilised granular layer over clay is estimated using finite element techniques in ABAQUS (a commercial finite element software). The model incorporates a range of soil parameters and layer thicknesses. The two-layered soil system in the model assumes a strong upper granular layer and a weak lower clay layer. The parametric results of the finite element analyses are used to develop design curves with dimensionless parameters in terms of linear gradient and the ratio of the undrained shear strength of clay to the effective vertical stress of the granular layer. The design curves are compared with the published results in the literature and found to be promising. The developed design curves are applied to estimate the minimum thickness of the granular layer and are compared with other existing methods. This application illustrates the simplicity of the proposed technique and reveals that the proposed approach yields a reasonable prediction for the bearing capacity when compared with other established methods.

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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 ($${{c}_{u}/p}_{0}$$ 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.

This study investigates the bearing capacity of a geogrid-reinforced granular working platform for heavy tracked plants on clay subgrade using a 2D plane strain finite element method. It substantially extends a case study investigated by incorporating wider soil parameters, depth-to-width ratios and geogrid stiffness modulus. The developed models are first verified by comparing them with the published literature and found to be in good agreement. The parametric modelling results are then used to develop a comprehensive set of design charts with non-dimensional parameters, bearing capacity ratio verses shear strength ratio, so that they can be directly used by practitioners. With the help of a design example, minimum design thickness of the granular working platform is compared and benchmarked with other established design methods. The results show that the proposed design charts and methods are comparable and provide reasonable predictions for the bearing capacity and working platform design thicknesses. A design example shows that thickness of the geogrid-reinforced granular base could be reduced from 1.2 to 55.6% for different geogrid strengths whereas the reduction is very nominal for soft geogrids ranging from only 1.2 to 3.0%.