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Retaining Wall Partial Failure

Retaining Wall Partial Failure

RE: Retaining Wall Partial Failure

They mention supporting soils being one concern, but the bottom half looks fine.

RE: Retaining Wall Partial Failure

These things fail pretty often. While they're marketed as being able to be constructed by monkeys, even monkeys need to follow a design and be supervised. Plus there's a lot of details that seem ticky tacky (like anchoring geotextile to the wall with plastic pins) that are the basis for the whole design.
There's a regional Geotechnical Company that gives Brown Bags where they buy you lunch and discuss some of their forensic work. I've been to three or four of them and at each one, there seems to be a segmental wall failure. It's almost always some misunderstanding of the design by the contractor.

RE: Retaining Wall Partial Failure

The tie backs at exterior corners and there influence on each other are difficult to analyze. I hope the contractor didn't cut them short because they were overlapping.

RE: Retaining Wall Partial Failure

Looks like a holey situation!

Interesting it occurred at the juncture of two planes where two directions tension forces occur due to transverse deflection.

Not a surprising situation here.

Mike McCann, PE, SE (WA, HI)


RE: Retaining Wall Partial Failure

This looks like the retaining wall being discussed could be this - there are several versions of these walls, they may not be equal.
https://www.concretenetwork.com/concrete/segmental...

The design manual at the above site looks like it provides methods to calculate design margin for internal sliding failure, failure of the geotextile to block connection, and pullout of the textile from the earth.
https://files.engineering.com/getfile.aspx?folder=...

If the cracking had been recognized as failure how would a repair be done?? Reinforce with install earth anchors?


RE: Retaining Wall Partial Failure

I'm busy scratching my head here...

While this is far from my expertise, that 'retaining' wall doesn't look anywhere sufficient at performing the job of retaining significant earth pressure that could occur on such a large escarpment. I would hope there is more than just that wall holding back that slope.

EDIT: ok, from the above post I would presume they've used geotextiles. Which would also make sense why the failure been seen at the top rather than the bottom. Less vertical load on the geotextile and possibly greater spacing.

I did find it interesting that the only claim was that the wall was structurally sound... Who cares about the wall, it is the mountain of earth behind it that is questionable.

RE: Retaining Wall Partial Failure

Is it me or does it look like that large pipe might have something to do with it?

Is that a surface drain which just disappears into the back fill?
Or maybe the concrete support for the guard rail?



BTW many of the websites fro some reason are getting wary of European visitors (GDPR etc) so it's difficult to see much.

Closer view


But the geotex bags look pretty solid behind the wall.

Looks like there is a void there on purpose?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Retaining Wall Partial Failure

Is that corrugated pipe there for drainage, or a cement sonotube for the railing above? I can't tell, but it looks like it is filled with cement. If it's for drainage, seems odd to just pour water into that empty cavity rather than channel it somewhere towards the bottom.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Retaining Wall Partial Failure

The void space behind the blocks was likely the location of the crushed stone drain that's typically used directly behind the blocks to promote drainage and eliminate hydrostatic pressures.

RE: Retaining Wall Partial Failure

I'm not familiar with the block type (anyone?) but I don't see a good facial connection for the blocks. I wonder if its purely friction based instead of using a lip or fiberglass pins?

RE: Retaining Wall Partial Failure

LittleInch and Mac - that's the foundation for the fence post. A questionable arrangement itself given its proximity to the wall.

RE: Retaining Wall Partial Failure

I'm guessing that either the surface was not sealed around the post foundation or that it was damaged possibly by a vehicle backing into the fence post.
That would allow rain water to enter and saturate the fill behind the facial blocks.
I think that the void is a result of the fill that was originally behind the blocks now being on the ground below.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Retaining Wall Partial Failure

Quote (MacGyverS2000)

I can't tell, but it looks like it is filled with cement.

I can assure you it is NOT cement...possibly concrete (cement mixed with aggregate/s and water) smile

RE: Retaining Wall Partial Failure

Pretty suspicious asphalt patch in the area of the failure.

Link

RE: Retaining Wall Partial Failure

Is this wall comprised of a primary structural wall (internal) and an external segmental block 'veneer' for appearance?

RE: Retaining Wall Partial Failure

Basically yes. The segmental walls often don't have mortar, only their weight and the interlocking connections. The lack of movement of the backfill, which looks like a set of geotex bags, seems to have held.

It's the lack of our failure of drainage that usually kill them like this.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Retaining Wall Partial Failure

Based on google earth photos sometime between 2/2018 and 10/2018 the asphalt was patched in the area behind the failure.
38°26'19.63"N 90°22'20.56"W

RE: Retaining Wall Partial Failure

Quote (LittleInch)

The lack of movement of the backfill, which looks like a set of geotex bags, seems to have held.

It's actually geogrid that typically gets installed between every 2 to 3 blocks to reinforce the backfill.

Quote (phamENG)

that's the foundation for the fence post. A questionable arrangement itself given its proximity to the wall.

Proprietary systems like Sleeve-It are used when fence posts have to be installed within 3 feet of the block. It's actually quite normal for a fence to be installed that close to the blocks.

RE: Retaining Wall Partial Failure

The same wall *appears* to be having issues at the 90° corner closer to the highway. Looks like some larger than normal vertical joints b/w blocks.

RE: Retaining Wall Partial Failure

That is an MSE wall (mechanically stabilized earth) with a veneer of segmental blocks pinned to the face. The blocks are not structural per se.

Edit: Here are some photographs of what looks like a similar failure.

Edit: Actually my link is a different system.

RE: Retaining Wall Partial Failure

MTNClimber - I agree that it's common, and I like that system you linked to. I would be on board with that. But in this application it looks like they used a large corrugated plastic pipe rather than a well thought out and properly designed system to work with the geotextiles.

Maybe I'm wrong and there's something out of view that helps to hold it together and give it sufficient strength.

RE: Retaining Wall Partial Failure

Zoom in on LittleInch's photos and you'll see a toe attached to the corrugated pipe. I'm not familiar with the product used at this site but it seems like it functions similarly. Tough to tell from video stills.

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