Geotechnical News June 2011
53
THESIS ABSTRACTS
shows a 5-12-fold decrease in Pg values compared to an HDPE geo-
membrane.
The effects of cold environments on the diffusion of VOCs are
studied. Five geomembranes are exposed to simulated cold climat-
ic conditions in the laboratory. Results from diffusion tests run at
2-24oC indicate Dg and Pg decrease with temperature. The tem-
perature and diffusion coefficients relationship follow the Arrhenius
equation. Activation energies of diffusionare calculated specific to
each geomembrane and contaminant. An HPDE geomembrane tak-
en from a field site in the Canadian Arctic after three years of expo-
sure to old climatic conditions shows minimal decreases in Dg and
Pg when compared to new HDPE. Finally, the diffusion of VOCs
through an HDPE geomembrane exhumed from a decommissioned
PCB landfill originally built in 1984 is examined. Profiling of PCB
concentrations in the landfill clay and composite liners is investi-
gated indicating minimal PCB diffusive migration after 25 years.
Advisor: Dr. R. Kerry Rowe, Professor and Canada Research
Chair in Geotechnical and Geoenvironmental Engineering, Queen’s
University
Three-Dimensional Kinematic Controls on
Rock Slope Stability Conditions
Marc-André Brideau
Marc-André Brideau,
,
+64 027 244 7867, School of Environment, University of Auckland,
Private Bag 92019, Auckland 1142, New Zealand
This thesis investigates the three-dimensional influence of dis-
continuity sets and topography on kinematics of rock slope stability
and failure mechanisms. A field data collection methodology was
developed to provide the inputs to a slope stability investigation that
utilises three-dimensional geometric, limit equilibrium and distinct
element codes. Conceptual slope geometries in addition to three
case studies are employed to evaluate the influence of discontinu-
ity set orientation and lateral kinematic confinement on the failure
mechanism and slope stability conditions. The influence of varying
the discontinuity persistence and block size in a three-dimensional
distinct element code are also investigated. Systematic studies of
these parameters are performed for the planar sliding and block
toppling failure mechanisms. This thesis presents the first detailed
description and slope stability analysis of the McAuley Creek Land-
slide and the Chehalis Lake Landslide. New data and analyses of
the potentially unstable rock mass at Third Peak on Turtle Mountain
are also presented. Two recently developed representations of com-
plex topography in the three-dimensional distinct element code are
applied to the case studies. The results obtained in this thesis are
compared to the description of other local and international large
rock slope failures published in the literature.
Keywords: slope stability; failure mechanism; numerical mod-
elling; three-dimensional; limit equilibrium; block theory; distinct
element code.
Supervisor: Professor Doug Stead, Department of Earth Sciences,
Simon Fraser University
Multi-Scale Characterization of Rock
Mass Discontinuities and Rock Slope
Geometry Using Terrestrial Remote
Sensing Techniques
Matthieu Sturzenegger
Matthieu
Sturzenegger,
Klohn
Crippen
Berger,
500 – 2955 Virtual Way, Vancouver, British Columbia, V5M 4X6,
email:
Terrestrial remote sensing techniques including both digital
photogrammetry and laser scanning, represent useful complements
to conventional field mapping and rock mass discontinuity charac-
terization. Several studies have highlighted practical advantages
at close-range (< 300 m), including the ability to map inaccessible
rock exposures and hazard reduction related to both traffic and rock-
fall along investigated outcrops. In addition, several authors have
demonstrated their potential to provide adequate quantification of
discontinuity parameters. Consequently, their incorporation into
rock slope stability investigations and design projects has grown
substantially over recent years.
As these techniques are increasingly applied by geologists and
geological engineers, it is important that their use be properly evalu-
ated. Furthermore, guidelines to optimize their application are re-
quired in a similar manner to standardization of conventional dis-
continuity mapping techniques. An important thesis objective is
to develop recommendations for optimal applications of terrestrial
remote sensing techniques for discontinuity characterization, based
on a quantitative evaluation of various registration approaches, sam-
pling bias and extended manual mapping of 3D digital models.
It is shown that simple registration networks can provide ad-
equate measurement of discontinuity geometry for engineering
purposes. The bias associated with remote sensing mapping is de-
scribed. The advantages of these techniques over conventional map-
ping are demonstrated, including reliable discontinuity orientation
measurements. Persistence can be precisely quantified instead of
approximately estimated, resulting in a new class for extremely per-
sistent discontinuities being suggested. Secondary roughness and
curvature can also be considered at larger scales. The techniques
are suitable for the definition of discontinuity sets, and the estima-
tion of both trace intensity and block size/shape, if sampling bias is
correctly accounted for. A new type of sampling window, suitable
for the incorporation of remote sensing data into discrete fracture
network models is presented.
Another significant thesis objective is the extension of terrestrial
digital photogrammetric methods to greater distances (> 1 km), us-
ing f = 200-400 mm lenses. This has required a careful investigation
of the observation scale effects on discontinuity parameters. The
method has been applied in a large open-pit mine and on the Palliser
Rockslide. It allows detailed characterization of the failure surfaces,
volume estimations and pre-slide topography reconstruction.
Keywords: rock mass discontinuity characterization; terrestrial
digital photogrammetry; terrestrial laser scanning; sampling bias;
observation scale; Palliser Rockslide; Frank Slide; Palabora Open
Pit Mine; failure surface; registration
Supervisor: Professor Doug Stead, Department of Earth Sciences,
Simon Fraser University
Exploring the Influence of Tactical Airfield
Layer Properties on Light Weight
Deflectometer Response
Christopher T. Senseney
Christopher T. Senseney,
The United States Air Force has traditionally used dynamic cone
penetrometer (DCP) evaluation of tactical airfields coupled with
empirical design methods. There are limitations with the DCP, e.g.,
penetration through cobbles, noisy, and time consuming. Addition-
ally, the pavement community is moving towards mechanistic-em-
pirical design methods wherein layer moduli are the primary input
parameter. The light weight deflectometer (LWD) is a device that
can assess soil moduli without the need to penetrate the soil surface,
and to perform testing in a quieter and timelier fashion. The inter-
