Push block retaining walls

[PSUengineer1]

General question...

anyone have design criteria for these types of walls (see attached pics of high side and low side). What is maximum allowed retainined soil height? how are these 2x2x 6 foot long sections supposed to be tied together vertically? any design info is greatly appreciated.

thanks

 

[concretemasonry]

That system is a common one that started out and was known variously as "come-back concrete" or "Mafia blocks" made by ready-mix suppliers in the same general sizes. There was no engineering involved and they were used to separate piles of different aggregate types. - totally no engineering.

There have been some changes made in the concrete units by adding shear keys and slots for keying units together and align them. Texture surfaces are also available.

In the end, they are used for gravity walls, relying on the mass, but there are some systems that have methods to tie units together and they may have some some propitiatory features offered, so it is best to check the possible local suppliers. It is certainly a local situation considering the freight costs and the need for significant cost for testing and verification of results.

The units remind me of the factory produced blocks for basements used in Russian homes and apartment buildings that are similar in size and desired use.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[BUGGAR]

Here in California, of course, they are called "ecology blocks".

Because they are very pretty.

No they use up waste concrete.

 

[SKJ25POL]

jimjxs263 (Structural), do you have few other shots different angles and from inside?
I believe I saw similar thing in one of the plants. The problem with these walls in my case was that one block at midheight was moving out a bit.

What's the height of the wall in your case?

 

[GeoPaveTraffic]

Unless these blocks are tied together by something, which is not ususally the case; then you have to analize the wall from the top down checking each block plus the blocks above it. At some height, depending on your backfill material and lateral forces, the blocks will fail either by sliding or toppeling.

Only way I've ever checked this type of wall is by hand.

Mike Lambert

 

[PEinc]

These stacked block "walls" can't support very much retained height unless the blocks are placed perpendicular to the wall face and/or the blocks are longer than the usual 2' width. If you want a wall higher than about 6 feet, you need a lot of blocks and the economics decrease. I have designed walls of this type using hand calcs as described by GeoPaveTraffic. I have also designed them using a gabion wall program with a different unit weight.

http://www.PeirceEngineering.com

 

[TehMightyEngineer]

If these blocks have been tested for the application then you can use blocks like these with geogrid to make a mechanically stabilized retaining wall (usually with some sort of shear key cast in the blocks).

Maine EIT, Civil/Structural.

 

[msquared48]

Right down the street from where I work in Woodinville, WA, they are reconstructing at least a 20 foot high, or better, wall of these blocks, using Geogrid now, starting from the south end. I will have to count the number of vertical blocks sometime.

Apparently, the Geogrid was not used when it was first constructed years ago and it was in danger of failing (gee, you think?). The North end had already been repaired with steel plates and tiebacks some years back, but looks like hell as the lateral movement was never corrected, only halted. Hopefully, they are going to reconstruct the entire wall.

Mike McCann, PE, SE (WA)