Seepage characteristics and landsliding of the A3 zone of the Barton Beds
Seepage characteristics and landsliding of the A3 zone of the Barton Beds
The most characteristic feature of the Barton Clay cliffs of Christchurch Bay is the presence of a number of preferred bedding plane surfaces of shearing. Most of these are contained within clay horizons and the reason for their preferential use by the coastal landslides is unknown. One surface, however, is at the base of the 2.7 m thick A3 Zone which consists of inter-bedded sand and clays. This surface is well exposed and forms a distinct feature in the cliffs throughout nearly the whole of the 1.5 mile coastal outcrop of the A3 Zone.
The paper discusses the reason why a shear surface is preferentially developed at this stratigraphic location. Three possible causes are discussed under the headings of (i) pore pressure fluctuation, (ii) seepage erosion and piping and (iii) equilibration response time. The first two are well established theories but the third is a new hypothesis derived from the original Bishop and Bjerrum theory of delayed equilibration. It is considered that the discussion is useful in the general context of landsliding at sand/clay junctions in overconsolidated soils.
107-114
Barton, M.E.
eea85a67-8def-49a1-a48c-f332310388d9
Thomson, R.I.
0a8ef4e9-3fca-495d-8105-7a846e8118d7
1986
Barton, M.E.
eea85a67-8def-49a1-a48c-f332310388d9
Thomson, R.I.
0a8ef4e9-3fca-495d-8105-7a846e8118d7
Barton, M.E. and Thomson, R.I.
(1986)
Seepage characteristics and landsliding of the A3 zone of the Barton Beds.
Geological Society, .
(doi:10.1144/GSL.ENG.1986.003.01.12).
Abstract
The most characteristic feature of the Barton Clay cliffs of Christchurch Bay is the presence of a number of preferred bedding plane surfaces of shearing. Most of these are contained within clay horizons and the reason for their preferential use by the coastal landslides is unknown. One surface, however, is at the base of the 2.7 m thick A3 Zone which consists of inter-bedded sand and clays. This surface is well exposed and forms a distinct feature in the cliffs throughout nearly the whole of the 1.5 mile coastal outcrop of the A3 Zone.
The paper discusses the reason why a shear surface is preferentially developed at this stratigraphic location. Three possible causes are discussed under the headings of (i) pore pressure fluctuation, (ii) seepage erosion and piping and (iii) equilibration response time. The first two are well established theories but the third is a new hypothesis derived from the original Bishop and Bjerrum theory of delayed equilibration. It is considered that the discussion is useful in the general context of landsliding at sand/clay junctions in overconsolidated soils.
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Published date: 1986
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Local EPrints ID: 435245
URI: http://eprints.soton.ac.uk/id/eprint/435245
PURE UUID: 754c7d63-a1a4-43e4-bfcb-489ca295f696
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Date deposited: 28 Oct 2019 17:30
Last modified: 16 Mar 2024 04:43
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R.I. Thomson
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