Retaining Wall Failure and Solution 2

[Bammer25]

Hello all. A friend of a friend contractor came to me. He has a masonry house on a steep slope under construction. Anyway, he had another engineer design his below grade walls and the guy has ironically disappeared. There is significant vertical cracking of mortar joints and block near the bottom of the wall. It retains approximately 25 (yes 25!) feet of soil. 12” block filled solid with number 5 bars 16” oc horizontally and vertically.

I already told him I would not in a million years take ownership of the design and stamp it, but I’d gladly help him out for free.

Any ideas? Building a shear wall is out of the question because the basement will be finished space. Are those carbon fiber tension straps any good? I have no experience with designing them. The wall is on the order of 25’ long where it os braced by other walls turning 90 degrees. He has all gravel (no soil) backfill and plans to pour a driveway (so more loading from cars).

I don’t want to tell him to kick rocks but this doesn’t look good to me. I’ll upload a picture in another post looking from the road.

 

[PEinc]

https://www.geofoam.com/

https://video.search.yahoo.com/sear...45e9506c862666dc0f6c1e26f84b7237&action=click

http://www.PeirceEngineering.com

 

[Standard American]

I would recommend removing the fill then installing some flat straps tied to the wall like they do with highway retaining walls. Also if it was not shored when backfilling it could have caused it to crack from the equipment vibration or compaction machine.
Geofoam is very expensive.

 

[JStructsteel]

@ 25', I would expect 14 to 16 wall to get it to work. Also sliding would be an issue.
Excavate and put in CLSM, something that reduces the pressure.

 

[HouseBoy]

I'm having trouble seeing how the 25 ft tall backfill is going to terminate around the ends of the wall.

Geofoam (which I THINK is poured in place) or Foam Blocks would be good too. They start out as 4 ft x 4 ft x 8 ft blocks and can be cut to almost any size. (I have priced them at ab out $50 per cubic ft BTW)

Seems like tie backs -OR- counter-forts (that would extend underneath he driveway) might be helpful.

I like the idea of strengthening the all AND reducing the load.

 

[BridgeSmith]

Geofoam (which I THINK is poured in place) or Foam Blocks would be good too.

What's commonly referred to as "geofoam" is expanded polystyrene foam (AKA 'styrofoam') blocks.

We've used it behind bridge abutments, and it might have cost $50 a cubic yard, nowhere near that much per cubic foot. I don't even think the specialty elastic geofoam we used one one occasion was that expensive.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[wrantler]

Make it an mse wall?
Drill anchors to tie the horiz reinforcing and backfill.

The engineer that 'fixes' this... has a beer on me.