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A probabilistic approach to the ultimate capacity of skirted foundations in spatially variable clay

Lookup NU author(s): Dr Tom CharltonORCiD, Dr Mohamed Rouainia



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


Skirted foundations are used in offshore applications to resist the large horizontal and moment loads thatare characteristic of the ocean environment. The combination of vertical–horizontal-moment (VHM)loading results in complicated stress conditions in the seabed and design is often based on VHM failureenvelopes. These have generally been constructed by numerical analysis using a deterministic characterisationof soil properties and disregard the natural spatial variability of marine sediments. In this study,spatial variability is taken into account by coupling a random field model with finite element analysis.The paper presents a probabilistic analysis of the ultimate capacity of skirted foundations in spatiallyvariable undrained clay. The increase of strength with depth typical of a marine clay is included in themodelling framework. Probabilistic failure envelopes are constructed to analyse the effect of spatial variabilitywhen skirted foundations are subjected to different combinations of VHM loading. The resultsshow that the probability of failure increases under high vertical loads and at peak moment capacityin the HM plane, suggesting that care should be taken in design at these areas of the failure envelope.The methodology demonstrates a straightforward and effective way of quantifying uncertainty in theultimate limit state design of offshore geotechnical structures and the results presented provide specificguidance for the design of skirted foundations.

Publication metadata

Author(s): Charlton TS, Rouainia M

Publication type: Article

Publication status: Published

Journal: Structural Safety

Year: 2017

Volume: 65

Pages: 126-136

Print publication date: 01/03/2017

Online publication date: 01/12/2016

Acceptance date: 06/05/2016

Date deposited: 26/09/2016

ISSN (print): 0167-4730

Publisher: Elsevier B.V.


DOI: 10.1016/j.strusafe.2016.05.002


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