Failure Mechanisms, Design Optimization, and Performance Enhancement of Skirted Foundations

https://doi.org/10.46610/JoGS.2026.v011i01.003

Abstract

Skirted foundations have emerged as an efficient alternative to conventional shallow foundations due to their enhanced bearing capacity, improved resistance to lateral loads, and superior performance in weak and heterogeneous soils. This study presents a comprehensive investigation into the failure mechanisms, design optimization, and performance enhancement of skirted foundations, based on both analytical interpretation and the synthesis of existing experimental findings. The failure mechanisms are systematically classified into foundation failure and soil failure, including base footing failure (punching shear and settlement), skirt failure (separation and deflection), bearing failure, and soil movement. A modified analytical framework is proposed by extending classical bearing capacity theory to incorporate soil confinement and skirt–soil interaction effects. The derived formulation demonstrates that the ultimate bearing capacity is significantly influenced by skirt depth-to-width ratio, embedment depth, soil properties, and interface friction characteristics. Parametric analysis indicates that increasing skirt depth enhances confinement and shifts the failure mode from general shear to confined plug failure and, eventually, punching failure. The results further highlight that the friction angle plays a dominant role in capacity enhancement, while cohesion contributes linearly. Circular skirted foundations exhibit superior performance due to uniform stress distribution and the mobilisation of hoop stress. The study also outlines key design optimization strategies, including appropriate selection of skirt geometry, soil improvement techniques, and dynamic analysis for seismic and offshore conditions. The proposed mechanistic approach provides a rational basis for understanding failure evolution and offers practical guidance for the safe and efficient design of skirted foundations in complex geotechnical environments.