The University of Southampton
University of Southampton Institutional Repository

An effective stress framework for the variation in penetration resistance due to episodes of remoulding and reconsolidation

An effective stress framework for the variation in penetration resistance due to episodes of remoulding and reconsolidation
An effective stress framework for the variation in penetration resistance due to episodes of remoulding and reconsolidation

Steel catenary risers (SCRs) are used to transport hydrocarbon products between offshore floating platforms and the seabed. Like many offshore structures, SCRs are subjected to gross cyclic movements during operation, which remould the seabed soil. The fatigue life of these structures is highly sensitive to the stiffness and strength of the seabed response. Accurate modelling of this behaviour requires a framework that can capture the changes in soil strength and stiffness that occur throughout the design life, accounting for remoulding during extreme events, and reconsolidation during the intervening periods. This paper describes such a framework, which is couched in effective stress terms. Soil softening during remoulding is predominantly associated with excess pore pressure generation, and the subsequent regain in strength is linked to the dissipation of excess pore pressure. The framework can describe the variation of resistance on a cylinder (i.e. a pipe) during any sequence of vertical cyclic motion, interspersed with pause periods. The framework is based on a critical state approach, with the current strength being linked to the current moisture content. The framework is shown to capture well the load-penetration response during an episodic T-bar penetrometer test. The operative soil strength is shown to vary dramatically throughout this event, with the softening effect of remoulding being almost entirely negated by a regain in strength associated with periods of partial or complete reconsolidation. The framework provides a basis for capturing these dramatic effects to aid pipeline and riser design (and other processes that involve gross remoulding and reconsolidation), without recourse to a full numerical simulation of the entire soil domain.

Clays, Consolidation, Cyclic loading, Offshore engineering, Shear strength, Soil/structure interaction
0016-8505
30-43
Hodder, M.S.
2c7413ea-6ff3-42ec-b93c-8ac67cede77e
White, D.J.
a986033d-d26d-4419-a3f3-20dc54efce93
Cassidy, M.J.
095b5237-97db-4ee5-9cb1-0b68d4731497
Hodder, M.S.
2c7413ea-6ff3-42ec-b93c-8ac67cede77e
White, D.J.
a986033d-d26d-4419-a3f3-20dc54efce93
Cassidy, M.J.
095b5237-97db-4ee5-9cb1-0b68d4731497

Hodder, M.S., White, D.J. and Cassidy, M.J. (2013) An effective stress framework for the variation in penetration resistance due to episodes of remoulding and reconsolidation. Géotechnique, 63 (1), 30-43. (doi:10.1680/geot.9.P.145).

Record type: Article

Abstract

Steel catenary risers (SCRs) are used to transport hydrocarbon products between offshore floating platforms and the seabed. Like many offshore structures, SCRs are subjected to gross cyclic movements during operation, which remould the seabed soil. The fatigue life of these structures is highly sensitive to the stiffness and strength of the seabed response. Accurate modelling of this behaviour requires a framework that can capture the changes in soil strength and stiffness that occur throughout the design life, accounting for remoulding during extreme events, and reconsolidation during the intervening periods. This paper describes such a framework, which is couched in effective stress terms. Soil softening during remoulding is predominantly associated with excess pore pressure generation, and the subsequent regain in strength is linked to the dissipation of excess pore pressure. The framework can describe the variation of resistance on a cylinder (i.e. a pipe) during any sequence of vertical cyclic motion, interspersed with pause periods. The framework is based on a critical state approach, with the current strength being linked to the current moisture content. The framework is shown to capture well the load-penetration response during an episodic T-bar penetrometer test. The operative soil strength is shown to vary dramatically throughout this event, with the softening effect of remoulding being almost entirely negated by a regain in strength associated with periods of partial or complete reconsolidation. The framework provides a basis for capturing these dramatic effects to aid pipeline and riser design (and other processes that involve gross remoulding and reconsolidation), without recourse to a full numerical simulation of the entire soil domain.

Full text not available from this repository.

More information

Published date: January 2013
Keywords: Clays, Consolidation, Cyclic loading, Offshore engineering, Shear strength, Soil/structure interaction

Identifiers

Local EPrints ID: 419920
URI: https://eprints.soton.ac.uk/id/eprint/419920
ISSN: 0016-8505
PURE UUID: fba5c80b-ad91-4369-a1de-ee8fce642c99
ORCID for D.J. White: ORCID iD orcid.org/0000-0002-2968-582X

Catalogue record

Date deposited: 23 Apr 2018 16:30
Last modified: 15 Aug 2019 00:25

Export record

Altmetrics

Contributors

Author: M.S. Hodder
Author: D.J. White ORCID iD
Author: M.J. Cassidy

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×