Undrained Sliding Resistance of Shallow Foundations Subject to Torsion

Abstract

Although the behavior of shallow foundations under vertical load combinations has been the subject of numerous studies, the response of shallow foundations subjected to combined horizontal and torsional loading has received considerably less attention. New offshore applications of shallow foundations for liquid natural gas facilities and other subsea structures have underscored the importance of the behavior of shallow embedded foundations subjected to combined in-plane translation and torsion. This study investigates the undrained bearing capacity of rectangular and square shallow foundations under eccentric horizontal loads through comparisons of various limit-equilibrium and plastic-limit analysis solutions to three-dimensional finite-element (FE) solutions. In general, the plastic-limit approach considered in this paper agrees well with the FE solutions, although it has some tendency to overpredict capacity at greater embedment depths. The studies revealed a general insensitivity in the shape of the yield envelope to variations in embedment depth, which permits a simplified analysis suitable for first-order estimates of load capacity. The variables considered in this study include footing aspect ratio, embedment depth, and load direction in addition to eccentricity.