Tunneling Repair

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Tunneling Repair

  1. 1. •Excavate the outside of the wall first,1 m wider than the hole & trackthe tunnel until the middle of thedam begins.•Step the sides of the excavated areainwards, back fill this area with thesame type of clay/soil forcontinuity in the wall.
  2. 2. •Excavate from inside the dam above the water line,if the water is not below the bottom side of the holeyou must create a temporary wall to stop any waterentering the wall.•Start 1m wider than the hole, track the tunnel throughto the compacted part of the back wall, dig wideenough until you reach the compacted soil(not water saturated soil).
  3. 3. •Leave the top of the tunnel intact if possible for theintegrity of the Wall.•The sides of the excavation need to bestepped in like a wedge from the insideof the wall out.•This concentrates the pressure of thewater to a smaller area in the centreof the wall for better holding strength.
  4. 4. •The section on the back of the wall needs noPolymer; it does require considerablecompaction as this area is a back stop for thematerial in the middle & front parts of the wall.•These quantities will be able to be calculatedonce the back wall is finished and compactedonce the front half of the wall has been•excavated.
  5. 5. •The internal walls of the tunnelneed to be moistened & dustedwith Polymer to act as anadhesive for the soil.•The clay/soil mixture needs to belightly moistened to allow thepolymer to stick to the soil, and then compact into the holeas tightly as possible in 1 cubic metre quantities.
  6. 6. •When compacting the clay/soilinto the centre of the wall, you will require 3 kg of Polymer for everycubic metre of soil.•The clay needs to be combinedwith a little water so it sticks tothe polymer when combiningthem before compacting back into the wall.
  7. 7. •When compacting the clay/soil into the front of the wall, you will require 5 kg of Polymer toevery cubic metre of soil.•The last 30cm of soil in the hole on the insidewall needs to have a larger quantity of Polymerin it to act as a cap. •Once this is complete, the entire wall needs to be treated with a liquid & granular Polymers to secure the surface area of the inside wall against any water ingress.•Liquid Polymer sprayed above the water line &powder/granules spread across the water.

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