Flexible ring net barriers that pass water and hold solid material in the stream bed: UX with posts for wide channels, VX without posts for narrow channels. They are installed as a series of levels; dimensioning uses the manufacturer’s DEBFLOW tool, based on 1:1 tests carried out with WSL.
What it does
A debris flow barrier does not close the stream bed: water and fine material pass through the ring net, while coarse blocks, trees and the mass of stones are held behind it. As the retained material fills the barrier, a new slope forms in front of the net and the energy of the next surge drops. Unlike a concrete check dam the structure is flexible; it takes impact forces by deforming and needs no large earthworks or concrete works.
UX and VX are Geobrugg AG products; Artusa has been Geobrugg's representative in Türkiye since 2009. The certified system comes with its own ring net; the steel ring net panels made in our own factory are used in separate works, made to size. Which panel is supplied is stated clearly in the quotation.
Types
| Type | Channel | Structure |
|---|---|---|
| UX | Wide channel | With posts; the support ropes are raised by the posts |
| VX | Narrow, V-shaped channel | Without posts; the ring net hangs from lateral anchors |
Channel width, bed gradient, expected event volume and block size determine the type and the number of barriers; several barriers installed in series split the retention volume.
Design principles
- The ring net is made of high-tensile steel wire; it carries high dynamic and static loads even when full.
- Ropes are protected against abrasion at impact points and can be replaced; braking elements absorb energy by controlled elongation.
- The manufacturer tested the systems together with WSL (Swiss Federal Institute for Forest, Snow and Landscape Research) in 1:1 field tests and developed the DEBFLOW dimensioning tool from the results. In our designs this tool is used together with the manufacturer; the catchment, the bed gradient and the estimated solid volume are measured on site as inputs.
What is measured during the survey
Catchment area and rainfall data, bed gradient and cross-section, traces of past events (deposit levels, scars on trees), transportable solid volume and block size, anchor ground at the barrier site. Without these numbers neither the type nor the number of levels is chosen; the decision table is on the debris flow and landslide protection page.
Maintenance
A full barrier is emptied; the time to empty it is set by observing the filling or by a notification from remote monitoring. After an event, the rope abrasion protection, the elongation of the braking elements and scour at the edge anchors are checked; the record is entered on the line's barrier tag: inspection, maintenance and service life.
Sources: Geobrugg AG product information (UX/VX, DEBFLOW).