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Design approach for rectangular mudmats under fully three-dimensional loading

Design approach for rectangular mudmats under fully three-dimensional loading
Design approach for rectangular mudmats under fully three-dimensional loading

Mudmats are used in the offshore oil and gas industry to support subsea infrastructure for pipeline terminations and well manifolds. Expansion and contraction of connected pipelines and jumpers due to changing thermal and pressure conditions impose fully three-dimensional loading on the foundations, dominated by horizontal, moment and torsional loading rather than high vertical loads. The mudmat foundations are rectangular, and include shallow skirts in order to increase capacity, particularly for sliding. Offshore design guidelines for shallow foundations tend to excessive conservatism; optimisation of mudmat capacity under general loading has thus become critical in order to keep foundation footprints within the limits of current installation vessels. The paper presents an alternative design method, based on failure envelopes derived from an extensive programme of three-dimensional finite-element analyses, focusing on the sliding and rotational capacity of the foundation. Starting from expressions that quantify the uniaxial capacity under each of the six degrees of freedom, failure envelope shapes for different biaxial combinations are developed. Ultimately, the allowable capacity under the six-degree-of-freedom loading is expressed in terms of a two-dimensional failure envelope for the resultant horizontal and moment loading, after due allowance for the vertical and torsional components of load.

Bearing capacity, Clays, Design, Failure, Footings/foundations, Numerical modelling
0016-8505
51-63
Feng, X.
b1a28be8-c603-4239-9c93-b2c14274e9c7
Randolph, M. F.
75caa33a-e630-4ae8-84cd-758797bf9633
Gourvenec, S.
6ff91ad8-1a91-42fe-a3f4-1b5d6f5ce0b8
Wallerand, R.
0cccbdeb-4e69-4654-9c33-e00ca5e4a860
Feng, X.
b1a28be8-c603-4239-9c93-b2c14274e9c7
Randolph, M. F.
75caa33a-e630-4ae8-84cd-758797bf9633
Gourvenec, S.
6ff91ad8-1a91-42fe-a3f4-1b5d6f5ce0b8
Wallerand, R.
0cccbdeb-4e69-4654-9c33-e00ca5e4a860

Feng, X., Randolph, M. F., Gourvenec, S. and Wallerand, R. (2014) Design approach for rectangular mudmats under fully three-dimensional loading. Geotechnique, 64 (1), 51-63. (doi:10.1680/geot.13.P.051).

Record type: Article

Abstract

Mudmats are used in the offshore oil and gas industry to support subsea infrastructure for pipeline terminations and well manifolds. Expansion and contraction of connected pipelines and jumpers due to changing thermal and pressure conditions impose fully three-dimensional loading on the foundations, dominated by horizontal, moment and torsional loading rather than high vertical loads. The mudmat foundations are rectangular, and include shallow skirts in order to increase capacity, particularly for sliding. Offshore design guidelines for shallow foundations tend to excessive conservatism; optimisation of mudmat capacity under general loading has thus become critical in order to keep foundation footprints within the limits of current installation vessels. The paper presents an alternative design method, based on failure envelopes derived from an extensive programme of three-dimensional finite-element analyses, focusing on the sliding and rotational capacity of the foundation. Starting from expressions that quantify the uniaxial capacity under each of the six degrees of freedom, failure envelope shapes for different biaxial combinations are developed. Ultimately, the allowable capacity under the six-degree-of-freedom loading is expressed in terms of a two-dimensional failure envelope for the resultant horizontal and moment loading, after due allowance for the vertical and torsional components of load.

Text
2014 Geotechnique 64_1_51-63 Feng et al. - Accepted Manuscript
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More information

Accepted/In Press date: 23 July 2013
e-pub ahead of print date: 23 September 2013
Published date: January 2014
Keywords: Bearing capacity, Clays, Design, Failure, Footings/foundations, Numerical modelling

Identifiers

Local EPrints ID: 414516
URI: http://eprints.soton.ac.uk/id/eprint/414516
ISSN: 0016-8505
PURE UUID: 2ee054b1-fe94-4015-b931-cd50dec81aa1
ORCID for S. Gourvenec: ORCID iD orcid.org/0000-0002-2628-7914

Catalogue record

Date deposited: 03 Oct 2017 16:31
Last modified: 16 Mar 2024 04:31

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Contributors

Author: X. Feng
Author: M. F. Randolph
Author: S. Gourvenec ORCID iD
Author: R. Wallerand

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