Al-Dabbagh, Thanoon H (1986) A study of residual shear strength of Namurian shale in respect of slopes in north Derbyshire. PhD thesis, University of Sheffield.
Abstract
This study deals with the classification and stability of number of landslips in North Derbyshire. The
engineering properties of materials controlling stability
are investigated with particular reference to residual
shear strength. The topography of the study area comprises
a series of valleys eroded into Carboniferous (Namurian)
sandstones and shales. Landslippage occurs on valley sides
where thick units of sandstone overlie comparatively
weaker shale.
Geomorphological studies using aerial photographs,
topographic maps and field observations have served as
primary data for establishing the style and geometry of
movement together with the present day stability condition. The landslip at Mam Tor has been given special
attention in view of its present instability. Two boreholes were drilled in which piezometers were installed
and movements have been monitored using EDM equipment.
The stability of each landslip as analysed iii terms
of a factor of safety against movement for both first
time, and subsequent movements, using the limit equilibrium method.
An extensive investigation of the engineering
properties of the mudrocks involved in the landslides
has been carried out. These studies include determination
of remoulded residual shear strength, grading, composition, and index properties of samples from boreholes,
the quarry at Hope Valley Cement Works and surface outcrops. Both the ring shear and shear box apparatuses were
employed and besides test method and sample pretreatment,
other causes of variation of residual shear strength have
been investigated. These include normal effective stress
value, loading sequence, rate of displacement as well
as sample composition, grading and classification.
It is concluded that ring shear tests give lower
residual shear strength values than the shear box method.
Also shale disaggregated by tumbling in water produces
a lower residual shear strength values than crushed material. It would appear that in conventional tests on
indurated shale a high proportion of clay aggregations
remain intact even when sheared.
The study indicates that the mobilized shear strength
in the field is little higher than the laboratory ring
shear one for thoroughly disaggregated shale. However,
it suggested that standard preparation methods and shear
box tests yield erroneously; high residual shear strength
for the indurated shale studied.
Metadata
Keywords: | Geology |
---|---|
Awarding institution: | University of Sheffield |
Academic unit: | Department of Geology |
Identification Number/EthosID: | uk.bl.ethos.303212 |
Depositing User: | EThOS Import Sheffield |
Date Deposited: | 19 Nov 2012 16:14 |
Last Modified: | 08 Aug 2013 08:50 |
Open Archives Initiative ID (OAI ID): | oai:etheses.whiterose.ac.uk:2993 |
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