Shotcrete and Soil nail during rain

[ANgK]

The contractor for shotcrete and soil-nail retaining wall want to wait until there is 7-9 days of continuous sunny day in forecast to start. It is impossible to find such a period until summer.
They can cover the wall during rain but they are concern about the the water saturating soil behind the wall.

My question is how to do shotcrete with a chance of rain and what method/protection to mitigate it.

 

[MTNClimber]

I've never had an issue with weather when it comes to soil nail wall installation. The only problem we ever had to deal with was cold weather concrete conditions. If they are really concerned with the face getting wet they could cover the fresh shotcrete. I'm not sure why they would be concerned about the soil behind the shotcrete becoming saturated unless you anticipate there being constant heavy seepage from the soil. I've had temporary soil nail walls be installed below the groundwater table but seepage was relatively small in the clayey glacial till. Additional information may help us understand their concerns.

What type of soil will be retained?
Where is groundwater?
What is on top of the wall? Landscape, hardscape, roadway?
How tall is the wall?

 

[ANgK]

cold weather is no longer an issue since there is no freezing night expected in the forseesable future

What type of soil will be retained? sandy soil
Where is groundwater? no ground water. This is the slope of the hill
What is on top of the wall? Landscape, hardscape, roadway? landscape. This is the dug out area on the side of the hill
How tall is the wall? 20 ft. The wall will be done in 3 sections of 7 ft height.

 

[MTNClimber]

I personally don't see any issues unless you expect to get a very large rain event. But that's something that can be anticipated and dealt with if it happens. 7 foot cut heights in sand will likely an issue unless you have a fair amount of fines. I would anticipate 5 foot cuts or less.

 

[Mad Mike]

Sounds like nonsense - I work in a rainy area where you could never get 7 days dry weather guaranteed, let alone continuous sun!

The rain can either

a) wash the face away in which case he has to start again - this would be a serious storm
b) some seepage through the face, which should be in low benches and easily treated
c) seepage into his drill holes

Regarding c) above - it could be that the contractor is using the wrong soil nail type and is now relying on drilled holes staying open instead of using self-drilling anchors- if this is the case, there will be a lot more petty complaints and claims coming your way...

Alternatively he's worried about setting and curing of the shotcrete, in which case I'd say your contractor is the problem.

All the best,
Mike

 

[Mad Mike]

PS - what the 7 to 9 day forecast predicts and what happens are two separate things - your contractor will find a sunny forecast and it will probably rain anyway!!!

 

[PEinc]

7' high unsupported open cuts? Sounds like an OSHA violation.

http://www.PeirceEngineering.com

 

[geojosh84]

7' lifts are not recommended, 4' is a better bet and will meet osha recs.

Where did the 7' lift come from? I hope that's not in the contract docs.