Abstract
The foundations of many large onshore and offshore structures are designed to be symmetrical polygons (e.g. octagons). However, the available analytical approaches for the ultimate limit state design of shallow foundations under combined loadings focus predominately on strip, rectangular and circular foundations. Although equivalent inscribed circular foundations have been recommended for foundation design by some guidelines, this simple approximation for octagonal foundations needs to be rigorously assessed due to the high dependence of the failure envelope on foundation shapes. The present study has investigated the general VHM (vertical, horizontal and moment) failure envelope of octagonal foundations under a zero-tension interface for undrained soil conditions using finite element analysis. The effects of soil strength heterogeneity and foundation embedment on the VHM failure envelope have been investigated. Analytical expressions have also been proposed to characterize the failure envelopes for use in design. The results show that octagonal foundations have larger bearing capacity than the corresponding circular foundations, and the difference (around 10%) between them is not negligible. A full 3-D analytical expression for the VHM failure envelope has also been proposed based on the calculated failure envelopes.
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The datasets generated during the current study are available from the corresponding author on reasonable request.
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Acknowledgements
The authors would like to acknowledge the financial support of Natural Sciences and Engineering Research Council of Canada (Grant No.: RGPIN-2015-06062).
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This work was supported by the Natural Sciences and Engineering Research Council of Canada (Grant Number RGPIN-2015–06062).
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Conceptualization: PH and TN; Methodology: PH and VD; Formal analysis and investigation: PH; Writing—original draft preparation: PH; Writing—review and editing: VD and TN; Funding acquisition: TN; Supervision: TN.
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He, P., Deshpande, V. & Newson, T. Undrained Capacity of Shallow Octagonal Foundations Under Combined VHM Loading. Geotech Geol Eng 41, 1275–1286 (2023). https://doi.org/10.1007/s10706-022-02334-z
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DOI: https://doi.org/10.1007/s10706-022-02334-z