Debris Flow & Shallow Landslide Protection

Transcription

1 Debris Flow & Shallow Landslide Protection NESSELWÄNGLE BEI REUTTE, AT

2 NESSELWÄNGLE BEI REUTTE Debris Flow & Shallow Landslide Protection Project Nesselwängle bei Reutte Project number P Street Nesselwängle 124 Zip code 6672 Place Nesselwängle Country/Region Austria Year of installation 2010 Customer Engineering Contractor Wildbach- und Lawinenverbauung WLV Ausserfern Wildbach- und Lawinenverbauung WLV Ausserfern Wildbach- und Lawinenverbauung WLV Ausserfern Initial situation In the fall of 2009, heavy local rainfall above Nesselwängle was responsible for the accumulation of debris caused by flooding. The inconspicuous Schmalecklesbach stream brought debris, humus, and deadwood down into the valley. A high proportion of deadwood led to logs becoming jammed. The woodland and hiking trail leading to the mountain cabin was washed away. The rock settled at the lower levels of meadowland and in the gardens neighboring the settlement. Description Following a consultation with Geobrugg, the regional site management of the WLV Ausserfern service for torrent and avalanche control decided to make this region the first to acquire a barrier system against falling rock. The geometry and the slopes of the Schmalecklesbach stream, positioned some 10 meters above the woodland trail, provide an ideal location for the installation of a debris flow barrier. The slopes of weathered, loosened, or solid dolomite rock ensure that the earth cannot work itself free at the sides. The UX120-H6 barrier is designed with two supports to provide optimum protection for the overall height of 6 meters and with an upper span of 23 meters, should an incident occur. By opening the nets, the barrier can be cleared out from the existing woodland trail following debris flow from the valley. Protected object Systems Touristic infrastructure, Residential area, Infrastructure UX120-H6 Corrosion protection GEOBRUGG SUPERCOATING System height System length 6.0 m 23 m Debris Flow & Shallow Landslide Protection Nesselwängle bei Reutte, AT 2/8

3 Number of barriers 1 Retention capacity 700 m³ Debris Flow & Shallow Landslide Protection Nesselwängle bei Reutte, AT 3/8

4 The UX120-H6 debris flow barrier protects paths and woodland trails against becoming blocked. Farmers are also happy that no further flood damage will be able to occur in the meadows in the future. Residents are pleased that they will no longer have to clear deposits from from their gardens and sludge from their homes. Everyone in the area can therefore now sleep soundly again. The catchment area of the Schmalecklesbach above Nesselwängle is at high risk of debris flow and the transportation of driftwood toward the settlement area. Until now, deadwood that has been carried along has clogged up this path below the woodland trail. Debris Flow & Shallow Landslide Protection Nesselwängle bei Reutte, AT 4/8

5 The mudslide rapidly dug its path, pouring out over the meadows and into the neighboring residential area. The WLV Ausserfern is located around 10 meters uphill of the woodland and hiking trails which lead to the mountain cabin often frequented by tourists an ideal place for installing a net barrier. Thanks to the raised ramp, the drilling works were taken care of quickly and without great difficulty using a digger with a mounted drill boom. Debris Flow & Shallow Landslide Protection Nesselwängle bei Reutte, AT 5/8

6 The drilled, 5-meter-long Titan 40/16 hollow bar anchors were pressed in with anchor grout and their flex heads screwed on. To transfer any lateral forces to the subsoil and to protect the bar anchors from bending, the flex heads were cast in reinforced foundations at a slight angle. After tensioning the support ropes with the energy-absorbing braking rings provided, both supports are positioned. The upper span of this 6-meter-high UX120-H6 debris flow barrier is 23 meters. The 95 m² nets are shackled to the support ropes, completing the installation of the debris flow barrier. Debris Flow & Shallow Landslide Protection Nesselwängle bei Reutte, AT 6/8

7 A freeboard of around 0.8 meters on the underside of the lower support ropes ensures free flow at times of low flow in the stream. Beneath the lower support ropes, relatively loose rings hang down to the bed of the stream in order to filter entrained branches, even in low water. A blockage of this path will no longer occur in the future. The officers at the WLV do not anticipate that this debris flow barrier will overflow. There is therefore no protection against abrasion on the upper support ropes. The flex heads, which are embedded in concrete in the foundation, are capable of bending up to 30 degrees on all sides in the vicinity of the anchor head without compromising their load capacity or ability to provide protection against corrosion. Debris Flow & Shallow Landslide Protection Nesselwängle bei Reutte, AT 7/8

8 The installed UX120-H6 debris flow barrier with a retention capacity of around 700 m³ protects the residents of Nesselwängle. For questions please contact our Geobrugg specialist at your side Alexander Bittendorfer Project Manager Germany South Phone Mobile Alexander.Bittendorfer@geobrugg.com Geobrugg info@geobrugg.com A company of the BRUGG Group Certified to ISO 9001 Debris Flow & Shallow Landslide Protection Nesselwängle bei Reutte, AT 8/8