Retaining Wall Failure

[fishdrivel]

No, not my wall! But rather a new large housing de"so simple" velopment up on a hill just finished this retaining wall a few months ago... then the biggest rainfall we've seen in years in San Diego came. Could have been worse, I guess but then again this is a pretty big failure in my eyes.

The wall I installed right around the corner handled the rain with no issues. But then again it has 30 yards of crushed rock in it.

I am certified for segmental retaining wall construction.
Before I took the classes and certified, I had a wall fail. It fell into a swimming pool.
Get a bunch of retaining wall contractors together over a couple of beers and you'll find that we have all "lost" a wall sometime in our careers.

The concept of segmental retaining walls is "so simple" Anyone can do it! Or so people think.
Hydrostatic pressure is #1 enemy of retaining walls, but there are many ways to fail.
If you do not understand the forces (even though you think you do) you cannot possibly engineer or build a wall.

I agree with another poster, this is probably low-bid - but not necessarily!
I oversaw construction of retaining walls in Japan. Many were not engineered correctly.
In Japan, they let Civil Engineers design from their regular staff. instead of using Engineers with specialized training and experience. They often fail.
If they are built by a company with lightly trained workers, they often make mistakes.

Nothing like a catastrophic failure to further your education!

 

[fishdrivel]

There are all sorts of products to tie retaining walls into to the dirt behind them. I can’t tell if any were used or if they just stacked the blocks. There should also be some drainage rock behind the wall. You can get by stacking blocks like that a few high and hold the dirt back been you start getting that high it takes a lot more work.

The most common fallacy is that the block are the retaining wall.
The retaining wall is the engineered backfill behind the wall.
The block is just a more durable face.

 

[Thomas]

Seeing more and more of walls tipping or being redone about 5 years because of poor drainage which cause by frost/frozen ground during the winter.

 

[Hay Dude]

Seeing more and more of walls tipping or being redone about 5 years because of poor drainage which cause by frost/frozen ground during the winter.

Land for development can be very expensive. Man is ever expanding into more development of less desirable ground that costs less money. Frequently the cheaper ground is steep.
Consequentially , more retaining walls are being built.

 

[Have tractor did travel]

I am certified for segmental retaining wall construction.
Before I took the classes and certified, I had a wall fail. It fell into a swimming pool.
Get a bunch of retaining wall contractors together over a couple of beers and you'll find that we have all "lost" a wall sometime in our careers.

Nothing like a catastrophic failure to further your education!

I have a bank barn wall failing. Never knew there was certification for "segmental retaining wall construction'. After I finish this post, I'll try to find one on Google.

Fishdrivel - thanks for your comment, as well. I was going to try to tie the wall into the earth, but now I'm going to see what the "certified" designer has to say.

 

[Rustyiron]

Water will always win, it might take years or it could be days. Then there's the "series of events" that's usually very expensive to prepare for and there's still "work arounds" for mother nature.

 

[Pixguy]

Building code here would have required mesh to be installed on multiple rows as the wall was built and backfilled plus crushed rock and irrigation pipe. Had that been done and the irrigation ultimately terminated into the street storm drain flow, I don't know why it would have failed like this. I guess at a certain point enough water will erode just about anything.

Either the mesh was left out, corners cut or the amount of water was more than the code planned for.

 

[fishdrivel]

Either the mesh was left out, corners cut or the amount of water was more than the code planned for.

Most retaining wall codes do not specify construction.
They require Engineering drawings stamped by an Engineer. The Engineer is responsible if the wall fails if installed according to engineered drawings.

On most walls, I designed the wall and paid an engineer for review. If the wall was in a difficult situation, I hired a design engineer with retaining wall experience. The wall in the picture, I would not have designed. The wall above it is a "surcharge" load on the lower wall. It does not appear that this was taken into account. I very much doubt an engineer designed that wall the way it was constructed.

 

[Streetcar]

I have a bank barn wall failing. Never knew there was certification for "segmental retaining wall construction'. After I finish this post, I'll try to find one on Google.

Fishdrivel - thanks for your comment, as well. I was going to try to tie the wall into the earth, but now I'm going to see what the "certified" designer has to say.

You need a geotechnical engineer to review wall. I have seen certified installers, but designers are professional engineers

 

[Have tractor did travel]

You need a geotechnical engineer to review wall. I have seen certified installers, but designers are professional engineers

Thank you. I only found one nearby "certified" installer, and no answering of phone on this, a Saturday morning. I'll look for a geotechnical engineer.
The former occupant's solution was to put 8 cubic foot blocks of concrete, stacked up against the failing wall. There are about 15 of them, I guess weighing about 500 lbs. each. Once someone tells me how to stabilize the wall, and that gets done. I'll have to figure how to get rid of the blocks.