Thomson, Fiona Mhairi (2002) Freeze-thaw experiments on some British soils. PhD thesis, University of Warwick.

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Abstract

Relic periglacial solifluction features cover most of Britain, particularly the Midlands and
the South, causing serious and continuing earthwork and construction problems. Although
the engineering significance of the presence of periglacial solifluction deposits is widely
appreciated, the mechanics of emplacement of these deposits has received surprisingly
little attention.
The principal objective of the research has been to investigate the freeze-thaw behaviour of
some clay soils in Britain which have been exposed to periglacial conditions. The
behaviour was examined using a Permafrost Oedometer or Permode, based on the
apparatus used by Morgenstern and Smith, (1973).
Tests have been carried out on Lias Clay, Weald Clay and Oxford Clay. In each test, a
specimen was placed under an applied stress and subjected to 24 hour cycles of freezing
and thawing. Freezing was mainly imposed from the top of the specimen downwards. The
tests were carried out undrained.
The pore water pressures were found to increase as a result of cyclic freeze-thaw
conditions. Greater pore water pressures were generally recorded at the top than at the base
of the specimen. This was considered to be due to moisture migration towards the freezing
front during freezing, and impeded filtration, (due to underlying frozen material), during
thaw.
The significance of the additional pore water pressures in terms of slope stability was
considered. A semi-infinite slope analysis model was used primarily, but reference was
made to other, similar research.
The analysis found that the predicted slope angle of failure is reduced significantly by
relatively low increases in pore water pressure. Greater increases in pore water pressure are
gained for soils of lower residual shear strength/higher plasticity.
It was determined that the generation of excess pore water pressure and corresponding
decrease in residual strength have considerable implications for the stability of slopes
previously exposed to periglacial conditions.

Item Type:	Thesis (PhD)
Subjects:	S Agriculture > S Agriculture (General) T Technology > TA Engineering (General). Civil engineering (General)
Library of Congress Subject Headings (LCSH):	Soils -- Effect of temperature on, Soils -- Testing, Cryobiology , Thawing
Official Date:	December 2002
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Petley, Derek
Extent:	xviii, 170 leaves
Language:	eng

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