Wednesday, 6 July 2011

Anchor lines

Once the geotextile is in place, the next step is to put in the anchor lines. These are buried 'duckbill' anchors which are used to secure the framesets to the ground. Normally, they would be used for the tiles directly, but the KAIRA tiles are connected directly to the framesets, so that means that the framesets need to be connected separately... and for the purposes of simplicity and uniformity, the same anchoring technique is used.

Although we have used these anchors before (during the anchoring of the winter test tiles), we didn't go into the details. So, the way these anchors work is as follows:
  • Nylon lines are attached to the anchors themselves. These lines are 1 metre long, but after knotting and looping, they are approx. 60 centimetres in length.
  • A pilot hole is drilled into the ground to a depth of 60 centimetres to match.
  • The anchors are then driven into the ground with a driving pin on a hammer tool.
  • Once inserted, tension is applied to the lines. The anchor turns to lock into the ground.
There are 8 anchor locations around each frameset, but there are additional anchor positions along the edges for extra strength.

A duckbill anchor.


The anchoring mechanism.


Han Wessels (lower left), instructs the trainees how to drive in the anchor lines.


While working at the far end of the site, and with high-power
tools, we use a diesel generator to provide electricity.



Some of the trainees putting in anchor lines...
drilling the pilot hole, driving rod for the anchors
and lifting tool to lock the anchors into place.


Progress on the anchoring has been great so far and a lot have now been done. However, there are a LOT of anchors points around the array: 488 in fact!

Photos: D. McKay-Bukowski

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