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Material Delivery
Double twist mesh rolls is supplied in roll form from the production facility in lengths of 25 m and 50 m. The roll dimension varies depending on the width and length of
the roll required and whether the woven wire has the additional PVC coating. The rolls are individually strapped at the factory for easy handling and transporting. Soil nails, anchors accessories etc., and installation equipment in the form of power actuated tools are not supplied by Yihang SA (Pty) Ltd and are to be sourced from approved suppliers. |
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Preparation and Placement
Placing double twist mesh rolls is an operation generally performed on faces or slopes close to the vertical and sometimes of considerable height. Although placing of the mesh may vary from site to site, the work may be reduced to four main phases.
1. Preparation of the surface tobe blanketed (removal of loose rock particles, barring down).
2. Placing the netting over the surface to be protected by lifting the rolls to the top of the face and then unrolling them.
3. Fixing the netting to the wall and tying them.
4. Final fastening of the net at the top, foot and if necessary the face.
By far the more onerous phase of the project is phase 2, the lifting and placement of the netting over the surface of the slope.
The first method consists of transporting the rolls to the top of the face and after aligning, opening and fixing them on the upper edge, allowing them to unroll downhill. This method is used when there is some access road to the top and when obstacles such as telephone, power lines and railway lines are at the foot of the hill.
The second method involves leaving the roll at the foot of the face, coupling a bar to it and lifting it up to the top of the face where it is to be fixed. A winch or crane would be required for this operation. Using cranes and winches may entail some operational constraints, for example, traffic delays and densities, and space restriction when working in narrow roads.
To overcome some of the above constraints, helicopters have been used to speed up operations and for faces higher than 25 m, helicopters are the best solution. |
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