9' Retaining Wall

[TPNY]

I am designing a retaining wall for a residential client and wanted to hear some opinions about the type and method I am using. The above-ground height ranges from 9' to 2.5'; the wall is too close (less than 8') to the property line, so installing geomesh would be impossible without digging up the neighbor's yard. So the next obvious choice is a cantilevered wall (which the owner's want to be veneered with stone). I planned on the footing being concrete (of course, but I wanted the wall to be CMU blocks which is more constructable in this case (I think). Some other details about the wall include a 90 degree corner at the 9' elevation, and land slopes up behind the proposed wall by 15 degrees (east wall)and 25 degrees (north wall). To meet 1.5 FS for global stability, I need a 5' footer at the tallest section of the wall. The CMU blocks also have me worried; I may need to double-up the wall in some areas to help with shear and moment capacity in the wall. Is there a better way to design this? Am approaching this wrong?

 

[SlideRuleEra]

Could you consider using a manufactured product such as:

http://www.keystonewalls.com/KShome.html

or

http://www.redi-rock.com/

There are others.

 

[VoyageofDiscovery]

Hi Zo40,

I believe global stability for overturning is 2.0 and sliding is 1.5, check with your local building code.

Regards

VOD

 

[TPNY]

IBC 2003 (the code reference for the county this is in) says 1.5 for lateral sliding and overturning.

The look of real stone (like a limestone) is what the owners want. The manufactered blocks are nice, but are not what they are looking for. Also, the 2000lb redi-rock blocks that require no geogrid, will be too difficult to get into the back yard. The house is already existing and the wall is being built to retain soil 6' from their new addition.

I appreciate your suggestions, anyhow; thank you.

 

[jheidt2543]

If you go with a concrete wall, you might consider a form liner that looks like limestone. Then you get the look all in one operation. Check with a formwork company like Symons, they can supply the liner in a number of patterns.

Just a thought.

 

[DRC1]

You might want to to look at large concrete blocks called deadmen in some places. They are 2ft x 3ft by 4 ft. Dimensions can varry. They are made by many precasters and are usually relatively inexpensive. If they have excess concrete, they will pour blocks instead of wasting it. They are used for a varrity of puroses including retaining walls. You could lay up a stone veneer face. It would be designed as a gravity wall. so you would brobly have about the same base width as the proposed footer.
Good Luck

 

[kkoloj]

CMU should work fine, but we typically use poured-in-place concrete when designing retaining walls--although this may be more expensive. If you haven't already, try using two different stems. That is, for the first 4' in height of the wall use 12" or 16" block and then use 8" block for the top 5'.

I regards to price, I have been told by some contractors that building retaining walls with block is not always cheaper than poured-in-place concrete. There is a lot of labor involved in setting each unit. Of course, there is a lot of labor involved in forming for poured-in-place as well.

Have you considered using shotcrete? The face of the wall can be finished by a skilled individual to just about any appearance imaginable.