WIT Press

Protection Systems Against Debris Flows


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R. Luis Fonseca, C. Raïmat Quintana, L. Laguna Megal & A. Roth


Debris flows are natural hazards which look like a combination of flood, land and rock slide. The phenomenon is also called mud or debris avalanche due to its similar flow behavior compared with snow avalanches. Debris flows regularly cause severe damages in mountainous areas like such as the Alps (Brig 1993, Sachseln 1997, Gondo 2000). Like rock fall, the debris flows loads act mainly dynamically on a protection barrier. But in contrast to falling rocks debris flows are not punctual impacts but a distributed load on the protection system. A further difference between the two hazards is the fact that rockfalls are single events while debris flows mostly occur in surges. Experiences from North America, Japan and Europe prove that flexible protection systems like the Geobrugg VX/UX Systems have an ideal bearing behavior to stop dynamic loads such as debris flows due to their large deformation capacity Keywords: debris flow, ring net, ROCCO, dynamic barrier, muds. 1 Introduction After the successful result of the introduction of the Geobrugg ROCCO® ring net several years ago, in the Rockfall Protection Systems, and as a result of the necessity of the avalanche control of materials dragged by the action of the water (rocks, mud, trees, etc.). Geobrugg was studying the possibilities of placing properly braced, this type of ring net within the natural channel of these flows, obtaining with it to stop the heavy and dangerous blocks and trees and being let pass the water. In February 1995 a debris flow of 60m3 was held back by a rockfall barrier of BRUGG Cable Products Inc. (BCPI) along California State Road 41 (County of San Luis Obispo). The result was that the road was not affected by the natural


debris flow, ring net, ROCCO, dynamic barrier, muds.