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The effects of hydrate on the strength and stiffness of some sands

The effects of hydrate on the strength and stiffness of some sands
The effects of hydrate on the strength and stiffness of some sands
Gas hydrates can form more or less at the same time as sea-floor sediment. They can have the effect of significantly stiffening and strengthening deep-ocean sediments. Subsequent increases in-situ temperature or decreases in pressure may trigger hydrate dissociation, leading to large reductions in the strength and stiffness of the sediment and possible sea-floor instability. Gas hydrate dissociation not only removes cementing. It also releases fresh water and significant amounts of trapped gas that are dependent on multiple factors such as type of sediment, available pore space, hydrate morphology and hydrate saturation. The presence of pock marks in areas of known sea-bed instability suggests that hydrate dissociation may have been a factor in triggering failure at these locations. Having reviewed the mechanisms by which the strength and stiffness of sea-bed sediment may be changed during dissociation, this paper reports the results of laboratory testing to evaluate the effects of loss of hydrate cement on strength and stiffness, for a range of sand-sized materials with differing particle size, specific surface area and particle shape, using a laboratory gas hydrate triaxial apparatus. The results suggest that both the strength and the stiffness of hydrate-cemented granular materials are affected significantly by the specific surface available for hydrate cementation and, to a certain extent, by the particle shape. Uniform coarse granular sediments of lower specific surface area can suffer significant loss of stiffness and strength upon hydrate dissociation, changing the sediment from dilative to contractive. Finer-grained sediments appear less affected by dissociation.
Gas hydrates, Stiffness, Strength, Sand, Triaxial testing
2169-9356
65-75
Madhusudhan, B.N.
e139e3d3-2992-4579-b3f0-4eec3ddae98c
Clayton, Christopher
8397d691-b35b-4d3f-a6d8-40678f233869
Priest, Jeffery A.
35e574b7-6239-4037-975e-296d388a4a08
Madhusudhan, B.N.
e139e3d3-2992-4579-b3f0-4eec3ddae98c
Clayton, Christopher
8397d691-b35b-4d3f-a6d8-40678f233869
Priest, Jeffery A.
35e574b7-6239-4037-975e-296d388a4a08

Madhusudhan, B.N., Clayton, Christopher and Priest, Jeffery A. (2019) The effects of hydrate on the strength and stiffness of some sands. Journal of Geophysical Research: Solid Earth, 124 (1), 65-75, [2018JB015880R]. (doi:10.1029/2018JB015880).

Record type: Article

Abstract

Gas hydrates can form more or less at the same time as sea-floor sediment. They can have the effect of significantly stiffening and strengthening deep-ocean sediments. Subsequent increases in-situ temperature or decreases in pressure may trigger hydrate dissociation, leading to large reductions in the strength and stiffness of the sediment and possible sea-floor instability. Gas hydrate dissociation not only removes cementing. It also releases fresh water and significant amounts of trapped gas that are dependent on multiple factors such as type of sediment, available pore space, hydrate morphology and hydrate saturation. The presence of pock marks in areas of known sea-bed instability suggests that hydrate dissociation may have been a factor in triggering failure at these locations. Having reviewed the mechanisms by which the strength and stiffness of sea-bed sediment may be changed during dissociation, this paper reports the results of laboratory testing to evaluate the effects of loss of hydrate cement on strength and stiffness, for a range of sand-sized materials with differing particle size, specific surface area and particle shape, using a laboratory gas hydrate triaxial apparatus. The results suggest that both the strength and the stiffness of hydrate-cemented granular materials are affected significantly by the specific surface available for hydrate cementation and, to a certain extent, by the particle shape. Uniform coarse granular sediments of lower specific surface area can suffer significant loss of stiffness and strength upon hydrate dissociation, changing the sediment from dilative to contractive. Finer-grained sediments appear less affected by dissociation.

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More information

Submitted date: 31 March 2018
Accepted/In Press date: 11 December 2018
e-pub ahead of print date: 12 December 2018
Published date: January 2019
Keywords: Gas hydrates, Stiffness, Strength, Sand, Triaxial testing

Identifiers

Local EPrints ID: 425479
URI: http://eprints.soton.ac.uk/id/eprint/425479
ISSN: 2169-9356
PURE UUID: 72f48944-d1aa-4959-afa2-1d67861e7610
ORCID for B.N. Madhusudhan: ORCID iD orcid.org/0000-0002-2570-5934
ORCID for Christopher Clayton: ORCID iD orcid.org/0000-0003-0071-8437

Catalogue record

Date deposited: 22 Oct 2018 16:30
Last modified: 07 Oct 2020 02:05

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