Our research is generally seeking to identify the geological controls for geotechnical parameters: it operates both in the field and in the laboratory.
To achieve this our research students work closely with colleagues in Soil Mechanics, Rock Mechanics, Mechanical Engineering, Chemistry and Chemical Engineering, as well as with those in Earth Science.
Visitors, occasional students, undergraduate students in their final year and postgraduate students attending the MSc in Engineering Geology are welcome to join the research school if they wish to complete an independent study relevant to current research interests.
An Industrial Forum is arranged at appropriate intervals to enable aspects of the research completed to be presented to a wider audience.
If you are either a scientist or an engineer and interested in our research, and would welcome more information about either it or the Industrial Forum, contact Dr. M H de Freitas.
Email: m.defreitas@ic.ac.uk
Current core activities are listed below (click for details):
 The
quantitative description of rocks in ways suitable for industrial purposes |
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The geotechnical evolution of Tertiary age basins |
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The movement of aqueous and non aqueous fluids
in fissured rock |
The problem:
To quantitatively describe rocks in new ways that are relevant for industrial
purposes.
Research so far:
Considerable progress has now been made with describing rock in terms
of its tensile strength and the time dependent changes upon it which occur
under different environments. Strain in extension has been studied at the
nano, micro and mesoscopic scale, and descriptions of anisotropy have been
linked with tensile strength in particular directions. This work has enabled
us to understand better the component of rock strength which cannot be
explained by sliding friction and the role of bonding in soil and rock.
We are now interested in the following subjects:
The influence of particle boundaries upon the strength and durability
of rock.
The tensile strength of mineral cement.
The use of rock analogues to study rock strength as a function of
porosity.
The relationship between tensile strength of rock and the area of
rock broken at failure.
The use of fractography to study failure in rock.
The tensile strength of the bond between rock and shotcrete.
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The
geotechnical evolution of Tertiary age basins
The problem:
The growing use of numerical modelling in geotechnics requires as good
an appreciation as possible of the structure and composition of the ground.
Increasing attention is being given to understanding the geological history
of the ground and its relationship to loading and unloading. Engineering
work in the London Basin is now providing evidence for evaluating the geological
evolution of the area from the Cretaceous to the Recent.
Research so far:
There is evidence to suggest that faults in the Chalk beneath the London Basin can be located from the position and orientation of rivers. The basic pattern of these faults and the primary blocks into which they divide the Basin has been predicted and this prediction is being tested using data obtained from engineering work. So far very strong coincidence between the location of these predicted boundaries and "unusual ground conditions" encountered by engineering construction in the Basin has been found. The research will therefore address two major areas of current interest.
The relationship between the medium and small scale structures
of the basin to sedimentation and erosion.
Whether differences in overconsolidation ratios and yield stress
ratios, recorded from different locations for the same sediments in the
same Basin, can be related to local geological history.
Indirect methods for locating faults.
Crustal
deformation in front of continental glaciers.
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The
movement of aqueous and non aqueous fluids in fissured rock
The problem:
Many fissures in rock are not smooth sided but rough. This causes the
aperture within which flow is occurring to have a complex geometry in which
the width available to flow varies from place to place. Despite this, the
heart of the analyses of flow in fissures is based upon the fissures being
bounded by faces which can be well described as parallel plates. Considerable
effort has been expended by researchers throughout the world on improving
these analyses and our understanding of the conditions they are supposed
to represent, but with little success.
Research so far:
Flow in fissures is conventionally described by an expression which
is a function of the cube of the opening of the fissure: known as the "cubic
law". Much simulation has been based on this however accurate measurements
of flow through a rough rock-like fissure (actually a cast of a real fissure)
and detailed measurements of the fissure opening associated with these
flows reveals, for the first time, that the theory we use for predicting
flow under these conditions may contain values for hydraulic conductivity
that are in error by as much as 40 % to 100 %. The reasons for this have
now being investigated.
We are now interested in the following subjects:
The relationship between head and discharge through a laboratory
model whose variations in aperture are known in detail and whose aperture
can be varied with precision.
Dr M H de Freitas CGeol
Reader in Engineering Geology
Email: m.defreitas@ic.ac.uk
Telephone: 0207 594 6023
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