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Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

The UX160-H4 debris flow system is filled following installation. In the picture, the ROCCO®-ring net R16/3/300 can be seen together with the secondary mesh TECCO® G65/3 used for the pre-filled application. The bottom slab, the lateral rock and the lateral shotcrete finish (not visible) are durably effective against the regressive erosion. The stability of the gallery is thus cost-effectively ensured.

Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

The gallery after the two floods and before installation of any protection measures. The regressive erosion endangers the BLS gallery due to the waterfall (photo source: Geoplan AG).

Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

The Maachi catchment area is between 10 and 15 km². With the Wiwannihorn it extends up to 3001 m above sea-level (picture source: modified according to swisstopo).

Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

Detailed view of the erosion gully before the measures. The drainage shaft clearly shows the original height of the terrain (photo source: Geoplan AG)

Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

The gallery prior to the measures. The edge of the erosion is hardly 2 metres away from the gallery wall.

Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

The UX160-H4 debris flow protection net. All brake rings are installed on the valley side, so they can function in case of future incidents. During overflow tests in the Illgraben (VS), it was demonstrated that no direct pressure shock acts on the net. Only the weight and the shear forces of the overflowing debris flow act upon the net. Thus it is not considered likely that the brakes will undergo major stresses.

Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

The system was filled as planned. In order that the filling material (diameter >= 10 cm) is not flushed out of the net (ring diameter 30 cm), a secondary mesh (TECCO® G65/3) was utilised.

Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

Detailed view of the spiral cable anchor: The vertical cables are guided through the loops of the spiral cable anchor.

Debris Flow & Shallow Landslide Protection - Galerie Maachi - BLS 2017

In order to avoid lateral erosion, the loose rock side was braced. The support cables are secured for future events by abrasion protection - even if the landslide net was back-filled during the construction phase.

 

Systems

 

System length

15 m - 15 m

 

Year of installation

2017

Initial situation

After the flooding in July and August 2015 of the Maachi (a mountain torrent in the Canton of Valais under the mountain Wiwannihorn in the municipalities of Ausserberg and Raron), considerable damage from erosion occurred on the valley side of the avalanche gallery of the BLS Southern Ramp (Bern-Lötschberg-Simplon railway line).

Until now, the mountain torrent Maachi had been lead through pipes under the gallery and through the erosion slope. However, the existing inlet already clogged up even with a small amount of debris. Alternatives were therefore sought.

Description

The office of Geoplan AG, Steg, VS was commissioned by the BLS AG to draw up immediate measures for securing the erosion slope and also the gallery.

The best option provides for the following:

During normal water level, the Maachi torrent will continue to flow down the existing inlet shaft of the Maachi pipe system. As a result, the erosion slope is not affected.

In case of flooding with debris or debris flow, the water will in future be intentionally fed over the gallery. This generates a sort of waterfall with a greater drop onto the erosion slope. This creates regressive erosion problems.

  • On the mountain-side of the crater (water-filled hollow), the slope is secured by a nailed-up supporting wall.
  • On the valley side of the waterfall impact, a debris flow net is installed and pre-filled.

The nailed-up supporting wall and the UX160-H4 debris flow system stops the regressive erosion. The solution is at the same time inexpensive.

Customer

BLS AG

Engineering

Alp Bauingenieure AG

Contractor

SILEX Felstechnik AG

Other participating companies

Geoplan AG

Protected object

Railway

Corrosion protection

GEOBRUGG SUPERCOATING

Your local contact

Kevin Coyle
 

Kevin Coyle

Regional Manager Northeast

Natural Hazards
Hydraulic Engineering
Geobrugg North America, LLC,3 Beaudet Terr,CT 06237 Columbia / United States Regional Manager Northeast

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Saleh Feidi
 

Saleh Feidi

Natural Hazards
Hydraulic Engineering
Geobrugg North America, LLC,8921 Emperor Ave.,91775 San Gabriel, California / United States

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John Kalejta
 

John Kalejta

Natural Hazards
Hydraulic Engineering
Geobrugg North America, LLC,KS 67226 Wichita / United States

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Bob Lyne
 

Bob Lyne

Natural Hazards
Hydraulic Engineering
Geobrugg North America, LLC,8004 Windspray Drive,NC 27358 Summerfield / United States

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Pierce Runnels, Civil Engineer
   

Pierce Runnels

General Manager Geobrugg North America

Natural Hazards
Geobrugg North America, LLC,22 Centro Algodones , Civil Engineer General Manager Geobrugg North America

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Tim Shevlin
 

Tim Shevlin

Natural Hazards
Geobrugg North America, LLC,OR 97302 Salem / United States

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