Fotodoku Milibach 2012 En
Transcript of Fotodoku Milibach 2012 En
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Multilevel fl exible debris fl ow barrier installationMilibach, Hasliberg / Switzerland
Photo documentation / September 2008Foto-Dokumentation / Mrz 2007Foto-Dokumentation / Mrz 2007
Multilevel debris fl ow barrier
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Multilevel debris fl ow barrier / Photo documentation / September 2008
Multilevel debris fl ow barrier holds back 2,000 m3 of debris fol-
lowing exceptionally heavy rain
On October 10, 2011, heavy rainfall triggered a shallow landslide containing
a total of 2,000 m3 of Alenienschiefer (schist) in the drainage area of the
Milibach river. 80 mm of rain had fallen in the space of 12 hours on top of a
70 cm layer of snow from the previous day. The Swiss Federal Offi ce for the
Environment (FOEN) rated these heavy rainfalls as a once-in-a-century occur-
rence. As recently as August 22, 2005, a storm in the Weiler Reuti and in
Meiringen caused serious debris coverage and severe damage. A cascade
comprising 13 fl exible debris fl ow barriers and with a retention volume of
up to 10,000 m3 was installed to protect the two settlements. For details,
please turn to page 4.
This multilevel debris fl ow barrier system successfully held back the latest
event of October 10, 2011, stopping an estimated 2,000 m3 of debris before
the shallow landslide had had chance to build up signifi cant erosive force,
as happened in 2005. The event fi lled barrier no. 2 completely and barrier
no. 5 partially. Barrier 1, which was situated above where the shallow lands-
lide was triggered, remained unaffected, while barriers 3 and 4 were not
fi lled up as they have a higher basal opening. Stopping the 2,000 m3 of
debris in good time helped prevent the shallow landslide further eroding
the unstable banks of the Milibach river and forestalled an even greater
shallow landslide that could have caused damage to the settlements further
downstream.
After an in-depth investigation during an on-site inspection, the customer
decided to leave barrier no. 2 fi lled to protect the riverbanks. The debris
held by barrier no. 5 is also to be left and should be carried away over time
as the water drains naturally.
10. October 2011
Satellite image of the storm that moved across the northern Swiss Alps on October 10 (source: SF Meteo website)
Multilevel fl exible debris fl ow barrierMilibach, Hasliberg, Switzerland
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Barrier no. 2 was fi lled by a landslide triggered nearby.
Barriers no. 2 and 5 held back a total of 2,000 m3 of material.
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22. August 2005
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Multilevel debris fl ow barrier / Photo documentation / September 2008
Multilevel debris fl ow barrier Milibach, Hasliberg, Bernese Oberland / Switzerland
Floods and a debris fl ow event occurred in the Milibach torrent on August
22, 2005 which resulted in serious debris coverage and damage in the Weiler
Reuti / Hasliberg and in Meiringen. The Milibach torrent above Reuti com-
prises of two creek sections, the Lauenenbach being situated in the upper
drainage area in the Alenienschiefer (schist). Due to the large amount of
precipitation, a total of some 13 000 m3 of loose material became detached
through water saturation in ca. 1 hour which then fl owed downhill as a mud-
fl ow in two to three batches (muddy debris fl ow, rich in fi ne material).
After the devastating rainfalls a suitable barrier system for debris fl ow re-
tention had to be evaluated. On the basis of various criteria the coordinators
decided in favor of a series of high-tensile ring net barriers from Geobrugg.
As support for the design fundamentals the Federal Research Institute for
Forest, Snow and Landscape (WSL) in Birmensdorf carried out physical model
trials parallel to the project planning.
Between autumn 2007 and summer 2008, over a 500 m long axis, thirteen
ring nets with heights of up to 7 m were mounted in series down the torrent
section. The exact sites were evaluated in the fi eld. The upstream side of the
fi rst net is designed primarily for energy conversion on the occurrence of
a debris fl ow. In some cases this fi rst net is destroyed and overfl owed. The
remaining nets are activated in stages. Back-fi lled nets are overfl owed by
subsequent events and act like fi lled concrete abutments. In an emergency
this net system with thirteen barriers retains a total of 10 000 m3 derived
from the starting zone.
Position of the thirteen barriers
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Debris fl ow starting zone
Marking off
Drilling in progress
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Multilevel debris fl ow barrier / Photo documentation / September 2008
Ring net installation
Ringnet ready for transportation by helicopter
Anchor foundation
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End of installation in August 2008
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It is the task of our engineers and partners to analyze the problem
together with you in detail and then, together with local consul-
tants, to present solutions. Painstaking planning is not the only
thing you can expect from us, however; since we have our own
production plants on three continents, we can offer not only short
delivery paths and times, but also optimal local customer service.
With a view towards a trouble-free execution, we deliver preas-
sembled and clearly identifi ed system components right to the con-
struction site. There we provide support, if desired, including tech-
nical support from installation right on up until acceptance of the
structure.
Rockfall barriers
Rockfall drapes
Slope stabilization systems
Debris fl ow barriers
Avalanche prevention structures
Open pit rockfall barriers
Special applications
Geobrugg AGGeohazard SolutionsAachstrasse 11 CH-8590 RomanshornPhone +41 71 466 81 55 Fax +41 71 466 81 50www.geobrugg.com [email protected]
Certifi ed to ISO 9001
Geobrugg protects people and infrastructures from the
forces of nature
A company of the BRUGG Group 1.20
3.03
.EN
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