Repairing a broken retaining wall made of concrete cylinders


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Old 09-30-20, 02:19 PM
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Question Repairing a broken retaining wall made of concrete cylinders

I’ll try to explain this briefly:

Old house in North Toronto. The City eliminated the ‘laneway' behind the houses and gave the to the property owners on either side. The owners of my home at the time, chose to build an extension to the garage.

From what I can tell, they supported the extra few feet of the garage as well as a new retaining wall/wall to the right of the garage with stacked concrete cylinders. This was 40y ago?

The 1-2 ft ‘retaining wall’ (made of cylinders) beside the garage has since given way. The 2-2.5 ft wall that stood on it, made of concrete block/poured concrete, supported by the metal poles has fallen.

I’ve removed about 20 cinderblocks and patio stones that had been piled there as a makeshift solution.

What’s left is the concrete cylinders, and the metal bars that were the part of the former wall.

I’m looking for advice around how to address this.

I’m not terribly concerned about this area eroding and am prepared to do repairs from time to time if necessary. A permanent solution would be best.

Open to any recommendations.

Pictures are walking along the side of the garage approaching the wall, then from the opposite side, facing the wall/back of garage.






 
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Old 09-30-20, 02:42 PM
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Those look like sample cores taken when inspecting a concrete pour. Often done for freeways and if you have a good eye you can sometimes spot the telltale circle in the road when driving.

I would look into engineered precast concrete retaining wall blocks. The good type are rarely sold at big box home centers and need to come from a more industrial concrete supplier. If you go to the manufacturers website you can find installation instructions.
 
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Old 10-01-20, 02:57 AM
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An interesting way to make a foundation.

If they were laid on a relatively sold base they are probably pretty stable, you state they have been there for 40 years.

I doubt your going to remove, just rebuild the wall with new block!
 
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Old 10-02-20, 08:41 AM
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Those look like sample cores taken when inspecting a concrete pour. Often done for freeways and if you have a good eye you can sometimes spot the telltale circle in the road when driving.
That would make sense as I hear the old owners worked for a major construction company thats contracted for a lot of roads in Toronto. The cylinders only support the 4' extension on the garage. The remainder of the foundation is likely more traditional.

If you look at the 4th pic, you can see:

the right side of the pic is the back of the garage. The cylinders are still in place behind the chain link. There's blocks on top of the cylinders, and everythings' solid.

the left side of the pic is the small space beside the garage where the cylinders have been pushed ~4-8" outwards. It's just these few cylinders I'm going to move.

My thought is to dig them out, & replace them in line with the wall.

But then how do i prevent them from simply shifting again?


 
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Old 10-02-20, 09:28 AM
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But then how do i prevent them from simply shifting again?

That is why I recommended a engineered retaining wall product. While the cores are strong there is nothing to prevent them from being pushed by the soil pressure on the back side.
 
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Old 12-18-20, 07:57 AM
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Thumbs up

Hey All, closing the loop on this for now.

Wanted to get something done regarding both the retaining wall and the downspout redirection before the frost, so here it is.

The plan: to reduce the chance of freezing, i was able to get about a 1/2" per foot slope. I did lay a bed of gravel to ensure the corrugated pipe didn't have any low points. Some of the corrugated pipe is exposed (right next to the house, in the area that gets sun.

What's interesting: In order to achieve this slope, I had to feed the corrugated pipe through the retaining wall (simply by leaving out one concrete core)

Also Interesting: There's (at least) 2 more rows of concrete cores buried. You can see one at my feet in this pic, then there's another below that.


Here's a pic with digging about 90% done and before gravel




50% gravel in place, levelling


And finished:



The pieces of wood are there in case the cores do shift, the lowest level can only move about half an inch.

I think this should do the job, but first test is this winter.

Thanks for the advice everyone
 
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Old 12-18-20, 01:27 PM
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Thank you for posting back with your solution. When you first asked your questions I never made the connection that you were the same person in the two threads.
 
 

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