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Construction of a Geobrugg VX debris flow barrier to protect SH65 in an area of very high rainfall

Project Overview


The highway at this location was damaged by a storm event in which resulted in a significant debris flow from well above the highway in a existing flood channel. The original culvert became blocked, causing inundation and partial failure of the highway embankment below the road.


Several options were considered by NZTA's Engineers Engeo to future proof the road from washing out again from debris flow events blocking the culverts and the Geobrugg VX80-H4 was specified.


Geovert Solution

As the site was highly channelised the narrow post free VX system was used and was anchored heavily into both embankments using 8m long 40/16 Ischebeck anchors. 2 destructive tests were completed to prove the design then 7 anchors were installed into each embankment with each tested to the 350kN design working load.

The barrier was constructed by running and tensioning cables, installing breaking elements and hanging the nets with a span width of 15m and an installation height of 9m. All works were completed
safety with the barrier constructed 30m up from the side of the road but still visible for routine maintenance inspections. A track was cut by
Geovert to allow for debris removal when required.

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