23.04.12
Protecting infrastructure against shallow landslides
Source: Rail Technology Magazine Apr/May 2012
Urs Brechbühl of Geobrugg AG explains work being done in Alpine regions and elsewhere to prevent landslides disrupting the rail network.
News reports of roads or railroad tracks blocked by debris from a shallow landslide are becoming more and more frequent. Why? The volume of rain falling not only in Alpine regions is increasing – and so too is the risk that heavy rainfall will loosen masses of earth and unconsolidated soil. But what is there to protect us from landslides?
On steep, unstable slopes, saturated layers of soil can form shallow landslides, which can trigger spontaneously and flow at relatively high speeds. Depending on the flow speed and volume of the displaced material, shallow landslides can have a highly destructive impact, disrupting traffic routes and causing major damage to infrastructure - such as the railway line in the eastern part of Switzerland, which had to be closed for several weeks.
As a result of this trend, railway companies must pay even greater attention to protecting railway lines from the unpredictable risk of landslides. Protection systems from Geobrugg are there to offer effective support. The global manufacturer from Switzerland has developed a flexible shallow landslide barrier made from high-tensile steel wire for protecting traffic routes and buildings on unchanneled slopes.
Passing the ‘crash tests’
Extensive 1:1 full-scale tests in three specially configured test centres were conducted in collaboration with independent experts from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) and the Swiss Federal Institute of Technology (ETH) Zurich. An impressive demonstration of the shallow landslide barrier’s effectiveness was given in the Veltheim test centre, among others.
However, it is always the local conditions that are decisive and not the exhaustive tests. Geobrugg AG thus offers customsed system solutions, not a one-size-fits-all product.
Geological data are measured on site and reproduced using the company’s own FARO simulation software.
The computer models are used to calculate the dimensions necessary to construct the net, e.g. the required distances between posts.
Every client thus receives a protection system that is tailored to the local risk situation.
Application possibilities
Rest and Be Thankful, a mountain pass in Argyll, Scotland, was the first project to use a shallow landslide barrier in combination with debris flow barriers. The barrier was constructed four meters high and 80 meters long to protect the road below from further landslides. In Giampilieri, Italy, in October 2009, the SP 33 highway was closed after being buried under a shallow landslide. As early as January 2010, the shallow landslide barrier installed in response to this event successfully held back a further shallow landslide, sparing the highway a repeat closure.
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