Maccaferri South Africa works to mitigate rockfalls onto a section of the N10 in Witkrants Nek, Eastern Cape.
The slopes on this section of the N10 highway are in places unstable and the rock is fragmented and prone to toppling and planar failures. Minimal vegetal cover exacerbates these problems.
There are three areas along this small stretch of the N10 which required mitigation. It was decided that a passive drapery Rockfall protection system was best suited for larger of these sections.
This being the main route to Johannesburg from Port Elizabeth, if left unattended, the situation would pose a continuous danger to motorists.
Design considerations for the rehabilitation works included the need to implement rapid remedial measures, accommodation of traffic during the construction phase of the project, difficult access, environmental concerns, need to employ unskilled laborers from the local community and the adoption of a rehabilitation system that was both flexible and durable.
The solution chosen was the implementation of Steelgrid MO.
This geo-composite product, used on the front face of the cut slope, provides a combination of mesh for the smaller rocks and high tensile steel cables that strengthen the mesh to support the bigger unstable rock fragments in order that these do not dislodge and fall onto the road. The system is anchored with cables at the slope crest with a small gabion catch-wall added at the toe to stop smaller rocks rolling onto the road.
A cut off drain at the summit of the slope was constructed and the existing top soil covered with Biomac to reduce erosion and promote greening.
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