In-situ testing in trench backfill: evidence of evolving backfill density
In-situ testing in trench backfill: evidence of evolving backfill density
The process of constructing and backfilling a seabed trench disturbs the soil. The properties of this disturbed soil and their variation with time are important for the design of pipelines and cables. Recent research has examined the properties of trenched and backfilled soils via laboratory testing, but limited field data exists to corroborate that work. This paper introduces a new dataset of in situ CPT testing to investigate trench backfill properties, from two project locations in the North Sea. At each site a series of CPTs have been conducted within backfill soil as well as adjacent virgin seabed, at a range of periods after the trenching process. The data are supplemented by laboratory test results. Conversion of the CPT data into estimates of relative density indicates that the initial backfill density is very low but rises back towards the very dense virgin conditions within a year, for these sites. The factors that control this behaviour are discussed, as well as the implications for upheaval buckling (UHB) design of pipelines.
476-483
Society for Underwater Technology
Powell, T.A.
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White, D.J.
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Alvarez-Borges, F.
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Fearn, M.
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1 January 2023
Powell, T.A.
f831c9f7-f12f-47f9-ab95-3a483651c77c
White, D.J.
a986033d-d26d-4419-a3f3-20dc54efce93
Alvarez-Borges, F.
5512cdfd-6ad3-475f-8aec-2fc767607314
Fearn, M.
6e8629e7-e23e-4590-9d3a-26044c7d3771
Powell, T.A., White, D.J., Alvarez-Borges, F. and Fearn, M.
(2023)
In-situ testing in trench backfill: evidence of evolving backfill density.
In Offshore Site Investigation Geotechnics 9th International Conference Proceeding.
Society for Underwater Technology.
.
(doi:10.3723/CEMU3785).
Record type:
Conference or Workshop Item
(Paper)
Abstract
The process of constructing and backfilling a seabed trench disturbs the soil. The properties of this disturbed soil and their variation with time are important for the design of pipelines and cables. Recent research has examined the properties of trenched and backfilled soils via laboratory testing, but limited field data exists to corroborate that work. This paper introduces a new dataset of in situ CPT testing to investigate trench backfill properties, from two project locations in the North Sea. At each site a series of CPTs have been conducted within backfill soil as well as adjacent virgin seabed, at a range of periods after the trenching process. The data are supplemented by laboratory test results. Conversion of the CPT data into estimates of relative density indicates that the initial backfill density is very low but rises back towards the very dense virgin conditions within a year, for these sites. The factors that control this behaviour are discussed, as well as the implications for upheaval buckling (UHB) design of pipelines.
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Published date: 1 January 2023
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© 2023, Society for Underwater Technology. All rights reserved.
Venue - Dates:
9th International Conference on Innovative Geotechnologies for Energy Transition, 2023, , London, United Kingdom, 2023-09-12 - 2023-09-14
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Local EPrints ID: 496149
URI: http://eprints.soton.ac.uk/id/eprint/496149
ISSN: 2754-6322
PURE UUID: 062d1d8e-87b9-4a14-a31a-3ee67101550a
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Date deposited: 05 Dec 2024 17:46
Last modified: 07 Dec 2024 03:07
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Author:
T.A. Powell
Author:
F. Alvarez-Borges
Author:
M. Fearn
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