1. Field Test Program
2. Location
3. Description of the site
4. Data collection
5. Examples of use of the test-site
6. Norwegian National research Program
7. Contacts
A total of five tests have been undertaken
in Norway by Sweco GrÖner.
These comprise:
- Field Test#1: The first field test (See Figure 1) was the
‘maximum cohesive’ embankment test that was undertaken
in September 2002 (coinciding with the 2nd IMPACT workshop).
The embankment was built mainly from clay and silt (D50 =
0.01 mm) with less than 15% sand and 25% of clay. The purpose
of this test was to better understand breach formation and
to identify the different failure mechanisms in homogeneous
cohesive embankments failed by overtopping.
[Note: An initial data set for this field test was released
to numerical modellers in August 2002 with modelling results
presented at the 2nd IMPACT workshop in Mo i Rana. However,
since the final test conditions proved to vary significantly
from the initial theoretical conditions that were provided
as a data set to modellers, a further data set with the actual
field test conditions was released in February 2003. (See
numerical modelling programme below for detailed info.). This
permitted modellers to undertake modelling runs that can be
compared directly against the field data.]
Figure 1: Geometry of Field Test
#1
Page:1 03/03/04
-Field Test#2: The second field test (See Figure 2) was the
¡®minimum cohesive¡¯ embankment test (Field Test #2) that
was undertaken in October 2002. The embankment was built mainly
from non-cohesive materials (D50˜5 mm) with less than 5 %
fines.The purpose of this test was to better understand breach
formation and to identify the different failure mechanisms
in homogeneous non-cohesive embankments failed by overtopping
and also to assess /inspect the effect of seepage on the breach
formation processes.
[Note: An initial data set for this test was also released
in August 2002 to numerical modellers and the modelling results
were presented in the 2nd IMPACT workshop in Mo i Rana. As
with the first test case, actual test conditions also varied
significantly from the target conditions hence a further data
set with the actual field test conditions was released for
simulation (See numerical modelling programme below for more
info)].
Figure 2: Geometry of Field Test
#2
- Field Test#3: The third field test was built as shown in
Figure 3 in August 2003. The upstream and downstream shoulders
were built from rock fill with a central moraine core. The
purpose of this test was to better understand breach formation
and to identify the different failure mechanisms in composite
embankments failed by< overtopping. Numerical modellers will
be asked to run at least one ‘blind’ and one ‘aware’
run with the data set of this test.
Figure 3: Geometry of Field Test #3
[Note: This field test was originally scheduled for 2002 but
due to poor weather conditions in Norway in autumn 2002 it
was delayed until summer 2003]
- Field Test#4: The fourth field test was built as shown in
Figure 4 in September 2003. The upstream and downstream shoulders
were built from rock fill with a central moraine core. The
purpose of this test was to better understand breach formation
and to identify the different failure mechanisms in composite
embankments failed by piping. Two triggering mechanisms were
used in this test case. Trigger mechanism #1 was a pipe perforated
at the top and had the bottom half removed with the last part
of it solid. The pipe was filled and surrounded by sand. The
second mechanism was similar to the first one but with the
sand fill extending from the bottom of the dam to the top.
Trigger mechanism #1 did not appeared to work so failure occurred
using Trigger mechanism #2.
As with each of the field tests, numerical modellers will
be invited to run at least one ‘blind’ and one
‘aware’ run with the field data sets.
Figure 4: Geometry of Field Test # 4
- Field Test #5: The fifth field test was built as shown in
Figure 5 in October 2003. The purpose of this test was to
better understand breach formation and to identify the different
failure mechanisms in homogeneous embankments failed by piping.
Only one trigger mechanism was used in this test which was
similar to the first mechanisms used in test #4. As with each
of the field tests, numerical modellers will be invited to
run at least one ‘blind’ and one ‘aware’ run with the field
data sets.
Figure 5: Geometry of Field Test #5
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A test site has been established in a river
valley downstream of Lake Røssvatnet, the second largest
reservoir in Norway. The test-site is situated in Northern
Norway (See
map). The reservoir belongs to SWECO,
one of the IMPACT project partners.
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3. Description of the
site The test-site is in rock canyon. The site has been carefully
prepared in order to prevent any leakage under or at the sides
of the test-dams. A sill made of concrete has been built at
the downstream side of the site. This sill is horizontal and
is used as reference for construction of test-dams (See
photo). A weir (See
photo) for measuring of leakage through the test-dam has
been built.
500 meters upstream of the test is the dam of Lake Røssvatnet.
(See map
, See
photo) Large-scale test dams up to 6 meters high and 36
meter (See
photo) long can be built across the river valley and then
subjected to heavy flood flows as water is released in a controlled
fashion from Lake Røssvatnet via the Røssvassdammen
(See
photo). Since the test site is upstream of a lake and
a further reservoir, discharge flows can be controlled and
contained, without risk of major flooding (See
photo).
The gates at the dam of Lake Røssvatnet have recently
been renewed and are easily operated so that exact amount
of water may be released during the tests. People from Sweco
SF operate the gates during the field tests.
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A wide range of data can be collected for each test, including
water levels, water-velocities, and flows. Several staff-gauges
upstream and downstream of the test-site have been calibrated
to facilitate the measurement of discharge. Pressure-sensors
are used to monitor the pore-pressures in the dam. Specially
designed sensors might be buried in the body of the dam in
the cases of breach-testing, indicate when movement occurs
and hence provide a profile of the time varying breach development
through the dam. In this way actual dambreak data can be collected
'on the spot' for later use in model development and verification.
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5. Examples of
use of the test-site The site offers a rare facility to undertake tests at large
scale, prototype scale or even larger than prototype scale,
depending upon the particular scenario being tested. Water
stored behind the test dam can reach approximately 90,000m3.
(See
Reservoir Capacity curve ) Combined with releases from
the Røssvatnet Dam of up to 450m3/s, this provides
the test site with enormous water potential with which to
test dam or embankment behaviour. Not only breaching tests
can be do, but also different other type of test e.g. test
of stability, test of monitoring equipment for dams
In 2001 the first test of a 6-meter high dam was made (See
photo , See
photo). The objective of that test was to investigate
the stability of a test-dam exposed to heavy leakage and to
learn about the breaching mechanism.
A series of experiments has been made in 2002 partly within
IMPACT, partly within the Norwegian Dam Safety test-program.
The first (cohesive - clay) test dam was breached in September
and timed in conjunction with an International workshop on
the project (See
photo , See
photo).
A series of test was made on the second (non-cohesive) dam:
- Test of the dam with a protected layer of rock on the
downstream side. (See
photo , See
photo).
- Test of the dam partly protected of rock (See
photo and See
photo)
- Breaching of the dam in mid October (See
photo , See
photo)
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6. Norwegian National
research Program Norway is running a dam safety project at the field test
site. This project is co-ordinated by EBL Kompetanse, The
Norwegian Electricity Industry Association EBL. A national
working group/consortium is formed of three of the leading
consulting Company in Norway: SWECO
Gröner AS, Norconsult
AS, Norwegian
Geotechnical Institute (NGI) and the Norwegian
University for Science and Technology(NTNU)
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If you are interested in more information about the test-site
and the possibilities test your own dams or embankments or
more information about the Norwegian project, you can contact:
Kjetil Arne Vaskinn, SWECO Gröner AS, Member of the
steering group and co-ordinator for the Norwegian part of
IMPACT
E-mail: kjetil.vaskinn@sweco.no
Phone: +47 73990200 or +47 93058575
or
Aslak Løvoll, Norconsult AS
Email: alo@norconsult.no
Phone: +47 67571213
or
Tore Valstad, NGI
Email: tva@ngi.no
Phone: +47 22023090
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