12 foot high retaining wall info for backfill
12 foot high retaining wall info for backfill
(OP)
We have a 12 foot high retaining wall (12" blocks). We installed drains around the concrete footers. To fill behind the wall will be approximately 4 feet wide and forty feet long and of course 12 block high. It will sit against a moist hill. Should the back fill be all gravel and if so does it matter what size? The block are filled with mortar for added strength. How long should the wall sit before we back fill?
Thanks
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RE: 12 foot high retaining wall info for backfill
RE: 12 foot high retaining wall info for backfill
RE: 12 foot high retaining wall info for backfill
Filling the block with mortar (grout should be used for grouting) and just filled cores with no rebar might increase the shear strength very slightly, but provide literally no help with flexure and that will be the major problem with a cantilevered wall. - By the way, 12 courses of normal concrete block is only 8' high.
A 12" SRW retaining wall block wall with geogrid will easily handle a 12' height, but unfortunately, they cannot be installed on next already installed concrete footing for structural purposes.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: 12 foot high retaining wall info for backfill
f-d
¡papá gordo ain’t no madre flaca!
RE: 12 foot high retaining wall info for backfill
BTW etifad - where are you located? If you're in the US you could look at your state DOT standards for backfill requirements.
RE: 12 foot high retaining wall info for backfill
RE: 12 foot high retaining wall info for backfill
RE: 12 foot high retaining wall info for backfill
I'd strongly suggest you go hire a structural engineer to check your design.
RE: 12 foot high retaining wall info for backfill
Attached is analysis from Digital Canal summary.
RE: 12 foot high retaining wall info for backfill
If the wall was designed and built as a proper cantilever (see the CRSI Design Handbook for examples), then your backfill should be lean clay, clayey sand, silty sand, or a similar material Avoid organics and expansive soils.
It may well be intended as a basement foundation wall, which relies for the floor diaphragm at the top for resistance (carrying the load from one side of the structure to another, rather than resisting the entire soil load as a cantilever (think flag pole.) Backfill partially unless the wall is designed to be a true cantilever. Construct the floor or other diaphragm, then finish backfilling.