How much bank can a "mafia block" hold back?

[dave1949]

Turn the wall 45* so that a vee is projecting into the slope?

 

[Scooby074]

Turn the wall 45* so that a vee is projecting into the slope?

That's an interesting idea. And the curve suggested above too.

However before I even think about this, I need to get my dump wagon built (lots of earth to move if I do this project) and get my new lawn landscaped. SWMBO will not appreciate it if I start another "excavation" before the lawn is done.

 

[dave1949]

Gosh Jason, Spring is only six days old and you are behind already. Funny how that happens. :laughing:

A curve or a vee, either would give more support and better drainage than a straight wall. Maybe the amount of water calls for a wider than normal stone bed behind the wall. You could run two sets of drain pipes, one about 2-3 feet above the other. I would definitely pin geotextile to the exposed dirt bank and leave enough at the top to fold over the top of the stone in the trench.

 

[capt_met]

you might consider compacting the fill gravel behind the wall as you go up. as well, every other course lay a geotextile cloth between the blocks and back into the slope to act as a tie back.

 

[CurlyDave]

I am not exactly sure what a "Mafia Block" is, but I have built many retaining walls with both Allen Block, and the large 2'x2'x4' blocks made from leftover concrete and sold by concrete companies, which I think is what you are referring to.

You can build to almost any height if you have a good enough base and if you "batter" the wall. Batter means either leaning the wall back into the slope, or stepping the rows of block back as you go up.

The upward sloping land behind the wall is called a "surcharge" and can be designed around, essentially use more batter.

The engineering design of such a wall is straightforward, and a local engineer can probably produce a design for you for a few hundred$.

This might not be what you want to hear, but I have a neighbor who built exactly the type of wall you are considering. He did it with "by guess and by golly" non-engineering. The wall fell down the first winter. He then paid to have the blocks re-stacked vertical, just like the first time, and the fell down again after that.

I went over to his place after the second failure and told him that he had to batter the wall if he wanted it to last--even calculated the amount of batter he needed. The "good old boy" who ran the crane didn't like the equations I used, and battered the third wall by the seat of his pants, but used a larger backset than I thought he needed. This was OK as it produced a greater safety factor, and the wall has been fine for 6 or 7 years now.

I have no idea what the whole episode cost, but it was a lot more than doing it right in the first place...

P.S. Whatever you do it is vital that you drain behind the wall.

 

[Lou66]

My brother bought an old shipping container 8 by 40 at a auction for 400 dollars,,rough looking but sound,, cut a slip inside a hill pushed it right in place,, covered the side up and left about five sticking out in front.. made a heck of a dry storage ben,, only cost was the container,, Lou

 

[vtsnowedin]

I am not exactly sure what a "Mafia Block" is, but I have built many retaining walls with both Allen Block, and the large 2'x2'x4' blocks made from leftover concrete and sold by concrete companies, which I think is what you are referring to.

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Well take your 2x2x4 and add a pair of shoes then drop it into the East river and you have your standard mafia block.

 

[muddstopper]

Mafia blocks are usually cast as 2x2x3 or 2x2x6 ft. The smaller blocks weigh around 1800lbs and the larger around 3600lbs. I dont know that you would necessary need a crane to place them. If you use the smaller blocks and have a decent size tractor, you could probably place them with the fel. Takes a large tractor for the larger blocks. If you lean the back course and backfill as you go up, you can also rise the outside runs on the same slope as you lean the back wall. this would allow for tight corners. It aint like you are going to be making 100ft runs so the slope on the side walls wouldnt be that noticable, unless you also plan on adding a roof at a later point. I am assuming the back wall is the 14ft wide, that is 3 of the 2x2x6 blocks wide and for the height, 4 or 5 high. For the 8ft side walls, you are only 2blocks long. Each end of the back wall will be supported by the side runs with only the center block being able to push out. I think you are over thinking this project, or I am looking at it wrong myself.

 

[Scooby074]

Well take your 2x2x4 and add a pair of shoes then drop it into the East river and you have your standard mafia block.

LOL. Might be hard to explain all those shoes in the wall to the Mrs.

 

[Scooby074]

Mafia blocks are usually cast as 2x2x3 or 2x2x6 ft. The smaller blocks weigh around 1800lbs and the larger around 3600lbs. I dont know that you would necessary need a crane to place them. If you use the smaller blocks and have a decent size tractor, you could probably place them with the fel. Takes a large tractor for the larger blocks. If you lean the back course and backfill as you go up, you can also rise the outside runs on the same slope as you lean the back wall. this would allow for tight corners. It aint like you are going to be making 100ft runs so the slope on the side walls wouldnt be that noticable, unless you also plan on adding a roof at a later point. I am assuming the back wall is the 14ft wide, that is 3 of the 2x2x6 blocks wide and for the height, 4 or 5 high. For the 8ft side walls, you are only 2blocks long. Each end of the back wall will be supported by the side runs with only the center block being able to push out. I think you are over thinking this project, or I am looking at it wrong myself.

I think that's about it.

Unfortunately my tractor is far to small to lift 3600#. Its only a BX so 700? is the limit.