Tie-down anchors to be installed under water
Tie-down anchors to be installed under water
(OP)
Dear fellow Engineers,
This is my problem. I need to build a cofferdam within an existing canal. The subsurface material is rock and it is very permeable. My plan is to first construct a braced cofferdam and then construct a concrete tremie seal (3 ft)/tie-down anchors all under water. Once the tremie slab hardens, the overlying water can be pumped out. It is expected that the anchor/slab system will resist the hydostatic uplift pressures (about 1200 psf). So this is the question. Can these anchors be installed and then fastened to the slab, all under water? Any suggestions?
This is my problem. I need to build a cofferdam within an existing canal. The subsurface material is rock and it is very permeable. My plan is to first construct a braced cofferdam and then construct a concrete tremie seal (3 ft)/tie-down anchors all under water. Once the tremie slab hardens, the overlying water can be pumped out. It is expected that the anchor/slab system will resist the hydostatic uplift pressures (about 1200 psf). So this is the question. Can these anchors be installed and then fastened to the slab, all under water? Any suggestions?





RE: Tie-down anchors to be installed under water
Then you avoid the type problem and safety concerns that you are seeing.
Keep it simple - cofferdam failure is catastrophic.
www.SlideRuleEra.net
RE: Tie-down anchors to be installed under water
If a failure (an open channel to water) occurs, the problem is extremely difficult to repair.
http://www.wmta.com
RE: Tie-down anchors to be installed under water
With rock at subgrade, you should not have boiling, piping, or a quick condition due to unbalanced hydrostatic head. However, you could have a lot of leakage through the rock and under the sheets if the rock surface is uneven and if the sheets can't penetrate a little into the rock. Possibly the seepage could be handled by pumping.
You need someone who is very experienced in cofferdam design.