International Symposium on Mitigative Measures against Snow ...

<strong>International</strong> <strong>Symposium</strong> on Mitigative Measures against Snow Avalanches
Egilsstaðir, Iceland, March 11–14, 2008
anchored concrete units and a concrete wall) was performed in order to determine which was
the most suitable for the project. The systems were analysed with respect to five factors.
These were cost, appearance/aesthetics, durabilty/robustness, construction and maintainability.
Each factor was given a certain value and ultimately a final grade calculated. The top
scorers were the gabions and the steel strips system (Línuhönnun 1999b). It may be noted that
these did not score highest on the aesthetic part. The client then made the decision to go with
the steel strips system. The system consists of heavily galvanized steel mesh in the front and
steel strips that are connected to the front and extend from the front into the barrier. The steel
strips have ribs to increase frictional capacities. This system has since then been used
successfully in two other projects with some modifications made to the initial manufacturer
specification to accommodate for Icelandic conditions. For instance the maximum diameter
of the frictional fill has been increased to up to 250mm from the initial 0/150 specifications.
A pull-out test conducted at Neskaupstaður even indicated that using a blasted rockfill 0/350
with good grading was capable of creating the necessary frictional interaction with the steel
strips. In addition the first two meters of the steel strips were painted with bitumastic paint to
further minimize the corrosion risk. The photographs below show the barrier at Neskaupstaður
under construction (left) and after completion (right).
Barrier built with steel mesh systems under
construction, Neskaupstaður 2000..
Barrier built with steel mesh systems, after
completion, Neskaupsstaður 2002
The construction of the barriers at Siglufjörður used a different approach. At Siglufjörður the
vertical walls are a much lower portion of the total effective height, only 4-5,5m of a total
effective height of 15m, with the rest of the barrier built with unreinforced fill to a 1:1.5 slope.
The vertical walls are built up with so called geo-cells and geo-grids for forming the front and
reinforcing the fill. A processed material is used for the cells and selected scree material is
used around the geogrids. The filling of the geocells is mostly done with small construction
equipment, bobcats and small vibratory plate rollers and with manual labor. The material
needs to be hand-raked into the cells and a considerable manpower is necessary compared to
the other solutions. The main advantage of the geocells is that the vertical walls can be
vegetated and a green front can be created. The photographs below show the barriers at
Siglufjörður under construction (left) and after completion (right).
Indriðason 193