Experimental Investigation of Subaqueous
Clay-Rich Debris Flows, Turbidity Generation
and Sediment Deposition
A. Zakeri, G. Si, J.D.G. Marr, and K. Høeg
Abstract The characteristics of submarine debris flows and the generated turbidity
as well as their relationship with the deposit thickness are discussed herein. There
is a gap in our understanding of the processes in which a submarine debris flow and
the overriding turbidity form seabed deposits and how the deposits relate to the parent landslide. The experimental program reported here studied subaqueous gravity
flows of different clay-rich slurries in a flume. The flume results provide insight
into the thickness of the slurry flows with the overriding turbidity clouds and the
deposited sediments and lays groundwork for future studies. The thickness of the
slurry head tends to decrease with increasing slurry clay content whereas the thickness of the turbidity overriding the slurry head tends to decrease with increasing
clay content. Further, the thickness of the deposited layer measured a few seconds
after termination of the slurry flow increases with clay content. Geometrically, the
flume experiments represented flowing debris of a landslide from 50 m to 120 m
water depths with a 600 m travelling distance and downstream velocities between
5 and 13.5 m/s.
Keywords Rheology • model scaling • subaqueous clay-rich debris flow • overriding turbidity thickness • deposited sediment thickness
A. Zakeri ()
Geotechnical Engineering Group, C-CORE, St. John’s, Newfoundland, Canada
International Centre for Geohazards (ICG), Sognsveien 72, 0855, Oslo, Norway
e-mail: arash.zakeri@c-core.ca
G. Si
Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern,
NO-0316 Oslo, Norway
J.D.G. Marr
National Center for Earth-Surface Dynamics, St. Anthony Falls Laboratory, Minneapolis, MN, USA
K. Høeg
Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern,
NO-0316 Oslo, Norway; International Centre for Geohazards (ICG),
Sognsveien 72, 0855, Oslo, Norway
D.C. Mosher et al. (eds.), Submarine Mass Movements and Their Consequences,
Advances in Natural and Technological Hazards Research, Vol 28,
© Springer Science + Business Media B.V. 2010
105
106
1
A. Zakeri et al.
Introduction
The dynamics of submarine debris flows and the resultant turbidity currents are
not fully understood. These processes are important as their occurrence can have
severe consequences for infrastructure (e.g. pipelines). Subaqueous debris flows
undergo various flow transformations, involving dilution and stripping of surface
materials into the ambient water in the form of an overriding, suspended sediment
cloud (turbidity), penetration of ambient water into the flow interior, and detachment or disintegration of hydroplaning flow fronts (Sohn 2000b). Unlike subaerial
debris flows, the head of a submarine debris flow devoid of permeable girth of
gravel and coarser particles, tends to hydroplane over a wedge of ambient water
sandwiched between the substrate and the overriding debris. The phenomenon has
been observed and studied in a number of recently conducted laboratory experiments (e.g. Harbitz et al. 2003; Ilstad et al. 2004a, b; Mohrig et al. 1998; Zakeri
et al. 2008) and numerically simulated (e.g. Gauer et al. 2006; Marr et al. 2002;
Zakeri et al. 2009).
The development of acoustic techniques for mapping the seafloor and imaging
the subsurface has led to a significant increase in understanding geomorphology
and geology. In particular, it has led to the identification of numerous deposits of
submarine landslides and debris flows on continental slopes. Interpretation of submarine debris flow deposits resulting from slope failures is hampered by the paucity of information concerning their dynamics. This lack of information hinders the
development and evaluation of numerical models necessary to understand deposition from submarine debris flow (Mohrig et al. 1999). Estimating debris flow thickness from a deposit thickness is difficult given that debris flows typically have
several surges. A deposit forms as result of the main debris flow event as well as
the progressive aggregation of individual surges. In many cases, deposition from
surges has laterally variable thickness, which complicates back-analysis of a debris
flow. As a result, some authors have resorted to the assumption that deposit thickness reflects flow thickness in their studies (e.g. Sohn 2000a).
There is a gap in understanding the process in which a submarine debris flow
and the overriding turbidity form the seabed deposits and how the deposits relate
to the parent landslide. The results of the experimental program reported herein
partly fill this gap. They lay the groundwork for future studies on clay-rich submarine debris flow dynamics, generated turbidity and sediment deposition. The
experimental program was part of a research study aimed at investigating drag
forces on submarine pipelines exerted by clay-rich debris flows. The slurries were
a mixture of kaolin clay, sand and water. Prior to the flume experiments, an extensive rheological study using laboratory rheometers was carried out to determine
the slurry properties and suitable mix design. The situations tested in the experiments have also been numerically analyzed using Computational Fluid Dynamics
(CFD) methods (Zakeri et al. 2009). Sonar data in particular proved important to
assess deposition from the debris flows during and shortly after termination of the
flow process.
Experimental Investigation of Subaqueous Clay-Rich Debris Flows
2
107
Experimental Program
2.1
Rheology Experiments
Table 1 presents slurry compositions and material properties for the different
experiments. Sand grain size plays an important factor in flow dynamics as slurries made with coarse sand particles are prone to gradual particle settlement during the flow causing change in rheology. As such, the slurries were prepared
using two different gradations of sand, Sand A (coarse) and Sand B (fine), to
investigate the effects of sand particle coarseness and to select a suitable sand for
the experiments.
Two different rheometers were used: the Brookfield DV-III Ultra vane-in-cup
and the Physica Modular Compact Rheometer (MCR) 300 Ball Measuring System
(BMS). The vane-in-cup rheometer has a number of advantages over others: minimal disruption to the sample during vane spindle immersion; low possibility of wall
slip effect; and more flexibility with the use of coarse grain size than the coaxialcylinder geometry (Barnes and Carnali 1990). The BMS rheometer was initially
developed in 1999 with the purpose of determining rheological behavior of construction materials (e.g. plaster and mortar) with maximum particle size of 10 mm,
and later adapted to conventional rotation rheometers (Schatzmann et al. 2003).
This exercise was carried out to determine which rheometer more appropriately
determines the rheological properties of the slurries when compared with the results
of the CFD back-analysis of the flume experiments.
Table 1 Slurry composition and material properties
Sand gradation
Mesh Size (mm)
Percentage material by mass
Slurry
10% Clay
15% Clay
20% Clay
25% Clay
30% Clay
35% Clay
Clay
10
15
20
25
30
35
Water
35
35
35
35
35
35
Sand
55
50
45
40
35
30
Density (kg/m3)
1,681.0
1,685.7
1,687.7
1,689.6
1,691.6
1,694.0
2.0
1.0
0.425
0.300
0.212
0.150
0.106
0.075
0.053
% Passing
Sand A
Sand B
100
96.5
76.8
–
12.0
–
0.6
–
–
–
–
100
99.5
95.5
77.5
33.5
8.5
0.5
Specific Gravity, Gs: Sand A = 2.7 and Sand B = 2.65
Uniformity coefficient (Cu) = 1.7 for both sands defined as the ratio of the maximum particle size
of the smallest 60% (d60) over that of the smallest 10% (d10) of the granular sample. Cu = 1 for a
single-sized soil, Cu < 3 a fairly uniform grading and Cu > 5 a well-graded (Whitlow 2001)
About 5% of the mass of sand was replaced by black diamond coal slag for visual purposes.
The black diamond slag had the same specific gravity and grain size distribution as the sand
108
A. Zakeri et al.
The slurry preparation and vane-in-cup rheology experiments were carried out
in accordance with the ASTM (D2196-05) procedures. Given the relatively recent
development of the BMS as a rheometer, there are no standards available to which
non-Newtonian fluids such as the slurries presented here could be tested. As such,
the ASTM (D2196-05) guidelines were followed as closely as possible in the BMS
tests. The slurries exhibited significant rheopectic behavior, as the fluid shear strength
increased with time. Therefore, time-dependency tests were also performed on each
slurry sample by studying the hysteresis loop. The Brookfield vane rheometer also
has the capability of directly measuring the static yield stress (undrained shear
strength) of a sample. For this purpose, a separate batch of slurry samples was
prepared and the tests were carried out in accordance with the ASTM (D 4648-94)
procedures.
2.2
Flume Experiments
The flume experimental program was designed at the International Centre for
Geohazards (ICG) at the Norwegian Geotechnical Institute (NGI) and conducted in
the St. Anthony Falls Laboratory (SAFL), Minneapolis, USA, in the spring of 2007.
A total of 50 experiments were carried out in a 0.20 m wide and 9.5 m long flume
suspended inside a 0.6 m wide tank (Fig. 1). The bed was rough with adjustable
slope (3° and 6°). For each experiment, 190 L of slurry was prepared in the mixing
tank located some 6 m above the flume and conveyed into the head tank. The instrumentation to image the flow consisted of:
• Two Canon GL2 cameras for measuring the slurry head velocities near the gate and
5.9 m downstream − 720 W × 480 H pixels frame size at 30 frames per second
• One submersible sonar to measure slurry flow and overriding turbidity heights.
Transducer: A301S-SU, Olympus NDT and pulser/receiver: DPR300, JSR
Ultrasonics
Sonar
(min. 0.62m from Bed)
3.0 m
Ball Valve
Plug
150mm I.D.
P.V.C. Pipe
0.45 m x 0.45 m x 0.85 m H
Flume Walls
- Clear
Plexiglass
- 6 mm
Thick
Head
Tank
0.3 m
Rod, Supporting Sonar
at Tip (20 mm O.D.)
GL2 Camera
(30 fps)
1.0 m
5.9 m
Gate
(0.2 m W x 0.075 m H)
0.20 m Wide Flume
Sloped at 3 and 6 Degrees GL2 Camera
(30 fps)
Chute
(0.2 m x 0.2 m x 0.3 m H)
10.0 m
Fig. 1 Experimental setup for flume experiments
2.3 m
Sonar Data
Acquisition
System
Slurry
Mixing
Tank
(190 Lit.)
Experimental Investigation of Subaqueous Clay-Rich Debris Flows
109
The high frequency sonar system is a stationary 500 kHz transceiver oriented
normal to the sloping bed, approximately 0.62 m above the bed surface (just
below the mean water surface). The data collection protocol involved two sampling periods: the first period at 50 Hz for 60 s and the second period at 6 Hz
for the next 30 min. For each ping, the system sampled backscatter at a rate of
8 MHz for 10,000 samples (1.25 ms). Zakeri et al. (2008) give the details of the
experimental procedures.
3
Model Scaling to Prototype Situations
Geometrically, the length scale in the flume experiments corresponds to 0.01. It
should be noted that the flume experiments only model a mass gravity flow of a
landslide that has turned into debris subsequent to failure (i.e. not the full scale
slope failure from triggering and initial disintegration). Thus, prototype water
depths at the gate and the sonar are 50 and 120 m, respectively, with a travel distance
of about 600 m. The water flow is turbulent both in the flume and prototype hence,
the Re similitude for the water is met on fixed boundaries. Slurry head velocities in
the experiments ranged between about 0.5 and 1.35 m/s that correspond to Froude
numbers ( Fr = U Δrgl r ) in the range of 0.45 to 1.25. The Froude number
formulation, l is some characteristic length of the prototype, g is gravitational
acceleration, U is fluid velocity, and r and Dr are fluid density and differential
density with respect to the ambient fluid, respectively. Given that the ratio of the
model to prototype velocities is equal to the square root of the geometric length
scale, the flume velocities correspond to a range of about 5 to 13.5 m/s in the prototype. The slurries are non-Newtonian fluids, therefore the Reynolds numbers
depend on the apparent viscosity which is a function of the shear rate. The shear
rate at the base is quite high – in the order of 103 s−1 or higher – dropping to 10 s−1
at about 2 mm from the base (Zakeri et al. 2009). Given the high shear rates at the
base, the Re similitude is also met for the slurry. The ratio of the model to prototype viscosities is equal to the geometric length scale to the power 1.5. As such,
the viscosity of the slurries corresponds to debris flow viscosities that are about
three orders of magnitude higher (i.e. slurry stresses of between about 7 and
250 Pa versus 7 to 250 kPa in a prototype situation). This is at least an order of
magnitude higher than what is expected in the prototype. Therefore, the similitude
of the slurries is distorted. However, this distortion mainly affects the study of the
flow dynamics within the slurry itself and not the system as a whole. The shear
rates at the slurry-water interface are high and therefore, the Re similitude at this
free-surface holds. A criterion in the flume experiments was that the slurry properties should remain constant (i.e. no sand particle settling). A given grain size can
be regarded as part of a fluid if the time scale of settling exceeds the duration of
the debris flow, particularly when the grains have diameter of about 0.05 mm
or less (Iverson 1997). Hence, only the Bagnold number (NBag), was considered.
The Bagnold number is defined as:
(
)
110
A. Zakeri et al.
N Bag =
rsd 2g 1 2
l
m app
(1)
where, rs is grain density, d is grain diameter, g is shear strain rate, and mapp is slurry/
debris flow apparent viscosity. l is the linear concentration defined by Bagnold
(1954) and is obtained from the following expression:
λ=
Vs1 3
13
Vmax
− Vs1 3
(2)
where, Vs is the grain volume fraction and Vmax is the maximum volume fraction
equal to 0.74 for spheres of equal diameter (Bagnold 1954) and 0.64 for wellgraded natural sands (Bagnold 1966). Assuming the maximum volume fraction for
Sand B to be 0.70, the linear concentration of Bagnold would be equal to 8.42.
For Sand B 10% clay slurry, the NBag at or very close to the base is about 8 and
17 for the d60 and d90 grain sizes, respectively. These values are far below the 40
limit, and therefore viscous effects are dominant must be considered for the flume
experiments. For Sand A slurries, these NBag values are close to or greater than 40.
4
4.1
Experimental Results, Analysis and Discussion
Results of Rheology Tests
Figure 2 presents the rheology test results. Slurries made with Sand B experience a
larger range of shear stresses than those made with Sand A. Particle size affects the
rheological behavior of suspension fluids through the specific surface defined as the
grain surface area per gram of mass (m2/g) – the smaller the particle, the higher the
specific surface. The behavior of fine-grained slurries is mainly controlled by the clayey
matrix. Decrease in sand size largely increases total surface area of particles per unit
volume, which in turn, increases the amount of bound water, and decreases the amount
of free water in the slurry system (Major and Pierson 1992). Sand A particles are about
2.6 times larger in diameter than Sand B which gives significantly higher specific surface for Sand B. This influences rheological characteristics of the 10% clay slurry made
with Sand A having shear stresses roughly twice than that of the 15% clay (Fig. 2).
Sand A particles in the 10% clay slurry settle at high shear rates in the rheology
tests, and at high rates of shear the fluid’s apparent viscosity decreased. Sand A
35% clay slurry exhibited a flow curve with decreasing shear stress (see the dip in
curve in Fig. 2 left) for shear rates less than about 5 s−1. As such, Sand B was used
for the slurries in the flume experiments. Results of the rheological experiments
were repeatable within ± 5%. The four mathematical models had a confidence
of fit of greater than 95% through the data (Table 2). All slurries exhibited strong
rheopectic characteristics (i.e. the shear strength increased with time). Therefore,
Experimental Investigation of Subaqueous Clay-Rich Debris Flows
300
Sand A Slurries
10% Clay
15% Clay
20% Clay
25% Clay
30% Clay
35% Clay
Herschel-Bulkley
Power-Law
200
100
0
Shear Stress (Pa)
300
Shear Stress (Pa)
111
Sand B Slurries
10% Clay
15% Clay
20% Clay
25% Clay
30% Clay
35% Clay
Herschel-Bulkley
Power-Law
200
100
0
0
10
20
30
40
50
60
0
Shear Rate (1/s)
10
20
30
40
50
60
Shear Rate (1/s)
Fig. 2 Rheological experiments results and Herschel-Bulkley and Power-Law mathematical
model fits: (left) Sand A (coarse) slurries and (right) Sand B (fine) slurries
Table 2 Slurry rheological models for slurries made with Sand B (fine). Shear stresses are in
Pascals
Slurry
Herschel-Bulkley
Power-Law
Casson
Bingham
.
.
.
.
t = 10.3g 0.125
t
= 10.6 + 0.20g
10% Clay
t = 7.5 + 3g 0.35
t = 9.0 + 0.04 g
.
.
.
.
t = 23.6 + 0.06 g
15% Clay
t = 20.5 + 5.5g 0.35 t = 25g 0.125
t = 26.7 + 0.37g
.
.
.
.
t = 50.4 + 0.10 g
t = 50g 0.12
t = 55.9 + 0.66g
20% Clay
t = 43 + 10g 0.35
.
.
.
.
t = 88.3 + 0.16 g
25% Clay
t = 85 + 12g 0.4
t = 91.5g 0.11
t = 97.6 + 1.11g
.
.
.
.
t = 115.2 + 0.27 g
30% Clay
t = 110 + 15g 0.45
t = 118g 0.125
t = 127.7 + 1.80g
.
.
.
.
35% Clay
t = 161 + 25g 0.4
t = 165g 0.13
t = 12. + 5.5 g
t = 168.0 + 0.31 g
slurry preparation and release in the flume experiments were designed to strictly
comply with that of the standard rheology tests. The flow curves measured from the
BMS rheology tests were generally 10% to 30% less than those obtained from the
vane-in-cup rheometer. The results of the CFD simulations of the flume experiments suggest that the vane-in-cup rheometer provides a better estimate of the rheological characteristics of the slurries (Zakeri et al. 2009).
The undrained shear strength (static yield stress) test results obtained by using
the vane rheometer in accordance with the ASTM (D 4648–94) procedures. In
magnitude, the yield stress values were close to the shear stresses measured at very
low shear rates (<< 1 s − 1) in the vane-in-cup rheology tests.
4.2
Results of the Sonar Observations
Sonar data provide information on the internal structure of the gravity flow. The
outgoing initial ping moves toward the bed, and as it density and/or velocity contrasts, it is partially reflected back to the transducer and recorded as backscatter. It
112
A. Zakeri et al.
Fig. 3 Greyscale rendering of the backscatter data (left) 38 s of recording: 15% clay slurry, head
velocity: 0.74 m/s and (right) 25 s of recording: 20% clay slurry, head velocity: 1.33 m/s. Vertical
grid spacing: 20 mm, horizontal grid spacing: 1 s
allows for accurate measurements of the flow geometries including thickness of the
initial slurry head, overriding turbidity but also the deposited layer after the termination
of the flow. Examples of the greyscale rendering of the backscatter data from the
runs are shown on Fig. 3. Figure 4 presents the summary results from the rendered
images. Table 3 summarizes the results for all 50 runs based on sonar data and camera recordings. A major portion of the turbidity is generated from the slurry head.
As the head flows downstream, thin sheets of materials are peeled off and diffuse
into the ambient water forming the turbidity. The water entrainment into the slurry
flow is restricted to a thin zone located at the surface of the slurry. The ambient water
does not penetrate deep enough into the slurry to affect its rheology. The generated
turbidity can be divided into two categories: the one overriding the slurry head and
the trailing turbidity over the deposited sediments. In general, the thickness of
the slurry head decreases with increasing clay content, whereas the thickness of the
overriding turbidity decreases with the increasing clay content. However, the trailing
turbidity thickness appears to be approximately the same for all slurries reaching the
water surface shortly after termination of the flow. The thickness of the deposited
layer measured a few seconds after termination of the slurry flow increases with the
Experimental Investigation of Subaqueous Clay-Rich Debris Flows
600
Flow
Turbidity
200
600
End of
Slurry Flow
(App. 1.7 Sec.)
Flow
400
Turbidity
200
0
0
Slurry 1
Head Vel. = 1.25 m/s
2
3
4
0
5
Slurry 1
0
Head Vel. = 1.25 m/s
Time (s)
600
200
Turbidity
3
4
5
Time (s)
600
End of
Slurry Flow
(App. 3.6 Sec.)
400
200
Turbidity
0
Slurry 1
0
Head Vel. = 1.0 m/s
2
3
4
0
5
0
Time (s)
Slurry 1
Head Vel. = 0.74 m/s
2
3
4
5
Time (s)
10% Clay
15% Clay
600
400
200
Turbidity
600
Flow
400
End of
Slurry Flow
(App. 2.3 Sec.)
200
Turbidity
0
Slurry 1
0
Head Vel. = 1.35 m/s
2
3
4
0
Slurry 1
0
Head Vel. = 1.16 m/s
5
Time (s)
2
3
4
5
Time (s)
600
400
End of
Slurry Flow
(App. 2.6 Sec.)
200
400
Flow
End of
Slurry Flow Turbidity
(App. 3.1 Sec.)
200
0
Slurry 1
0
Head Vel. = 0.88 m/s
2
3
4
0
5
0
Time (s)
Slurry 1
Head Vel. = 0.87 m/s
2
3
4
5
Time (s)
20% Clay
25% Clay
600
End of
Slurry Flow
Turbidity (App. 2.7 Sec.)
200
600
Flow
End of
Slurry Flow
(App. 1.8 Sec.)
400
200
Turbidity
0
Slurry 1
Head Vel. = 1.07 m/s
2
3
4
0
5
Slurry 1
0
Head Vel. = 0.80 m/s
Time (s)
2
3
4
5
Time (s)
600
End of
Slurry Flow
(App. 3.6 Sec.)
200
End of
Slurry Flow
(App. 2.7 Sec.)
400
200
Turbidity
0
0
Slurry 1
Head Vel. = 0.80 m/s
2
3
Time (s)
30% Clay
4
5
Height (mm)
Turbidity
600
Height (mm)
400
Flow
Height (mm)
400
Height (mm)
Flow
0
Height (mm)
Turbidity
600
Height (mm)
Flow
Height (mm)
End of
Slurry Flow
(App. 1.7 Sec.)
Height (mm)
Flow
Height (mm)
400
2
Flow
Height (mm)
End of
Slurry Flow
(App. 3.3 Sec.)
Flow
Height (mm)
400
Height (mm)
End of
Slurry Flow
(App. 1.6 Sec.)
113
0
0
Slurry 1
Head Vel. = 0.56 m/s
2
3
4
5
Time (s)
35% Clay
Fig. 4 Analysis results of the grayscale rendered images produced from the experiments with the
maximum and minimum slurry head velocities
clay content, after which gravity-controlled compaction or consolidation will start.
The distinct shape of the slurry head (single or double-hump) is a result of the velocity field developed in the water due to the momentum transfer between the water and
slurry (Zakeri 2007; Zakeri et al. 2009). The flow in the water is in the form of large
circulating eddy vertices slightly lagging behind the slurry head, which in turn
affects the its shape. The extent of which the shape of the slurry head is affected by
this momentum transfer depends on the strength of the slurry (e.g. a more pronounced double hump shape in slurries of 25% clay and less).
114
A. Zakeri et al.
Table 3 Analysis results based on the rendered grayscale sonar data and camera recordings
Slurry
Flowing slurry head
(% Clay) characteristics
Deposit thickness
Turbidity thickness Thickness
of deposited as percentage of
overriding slurry
layer (mm)b slurry flow
head (mm)a
Velocity (m/s) Height (mm)a
Min. Max.
Min. Max Min.
Max
Min.
Max Min. (%) Max (%)
10%
1.0
1.25
225 365
95
215
5
10
2.2
15%
0.74 1.25
210 270
140
165
27
35
12.9
20%
0.88 1.35
300 310
60
70
32
35
10.7
25%
0.87 1.16
210 225
70
155
52
62
24.8
30%
0.80 1.07
150 185
90
95
52
64
34.7
35%
0.56 0.80
120 145
90
75
53
65
44.2
a
The measured values were rounded off to the nearest fifth millimeter dividend
b
The readings were rounded off to nearest millimeter
5
2.7
13.0
11.3
27.6
35.1
44.8
Conclusions
The effects of particle size and time-dependency characteristics have to be
considered when studying sediment deposition from debris flows. The vanein-cup rheometer better captures the rheological behavior of the kaolin-sand-water
slurries than the BMS rheometer. The slurry head velocities in the flume experiments ranged between about 0.5 and 1.35 m/s, which correspond to prototype
velocities ranging from 5 to 13.5 m/s for a clay-rich submarine debris flow.
Flume experiments modelled transition between subcritical and supercritical
flow regimes.
Using sonar data, it is possible measure flow geometries accurately, including
the thickness of initial slurry head, overriding turbidity, and the layer deposited
after termination of the flow. The results showed that the thickness of the slurry
head tends to decrease with increase in clay content whereas the thickness of the
overriding turbidity decreases with clay content. However, the trailing turbidity
thickness is approximately the same for all slurries reaching the water surface
shortly after termination of the flow. The thickness of the deposited layer measured
a few seconds after termination of the slurry flow increased with the clay content.
With further investigation, it may be possible to relate the measured deposit thicknesses to those of similar prototype conditions (e.g. with the help of the conventional consolidation theory, etc.). The work presented here outlines the procedures
for similar type experiments and lays the groundwork for future studies.
Acknowledgements The work (ICG Contribution No. 229) presented here was supported by the
Research Council of Norway through the International Centre for Geohazards (ICG) and the LeifEiriksson stipend awarded to the first author. Their support is gratefully acknowledged. We also
extend our thanks to Statoil for funding the experimental program and to the St. Anthony Falls
Laboratory (SAFL) staff for their contributions to the experiments. The authors are thankful to Dr.
Maarten Vanneste and Prof. Christopher Baxter for their review efforts and constructive comments.
Experimental Investigation of Subaqueous Clay-Rich Debris Flows
115
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