Retaining Wall without heel and toe
Retaining Wall without heel and toe
(OP)
I am considering a retaining wall without the heel and toe since it will be on solid limestone. Can the anchor steel be sufficient for overturning and can the rock be considered as an infinite footer? Wall height will be about 10'. Plan on using epoxy grouted anchor bars.





RE: Retaining Wall without heel and toe
There will be a very large moment at the base of the wall that you have suggested controling with anchors. The traditional approach of a heel and toe are simple means of providing a lever arm to resist the moment. The other approach is to provide a wall that is wider at the base than the top. I suspect that a wall can designed and built without a heel by I would wonder why one would not use a heel?
RE: Retaining Wall without heel and toe
I think he's trying to avoid excavating the rock...
RE: Retaining Wall without heel and toe
You might also consider socketing piles into the rock if the number of foundation anchor dowels gets to be high.
RE: Retaining Wall without heel and toe
Best regards and
RE: Retaining Wall without heel and toe
What will be retained by the wall? Is an MSE feasible? Tie-backs and deadman anchors? You used the phrase, "Plan on using epoxy grouted anchor bars." Is the wall "retaining" limestone or decomposed limestone, with the anchor bars grouted into the "rock"?
BigH:
Too bad this Internet thing won't transmit/receive libations...the emoticons are great
RE: Retaining Wall without heel and toe
The moment arm on the anchor steel is large. It is definitely a cantilever beam, but I was also worried about the anchorage steel development length. Calculations show it will work, but I like other opinions.
Thanks
RE: Retaining Wall without heel and toe
In reality, you only have a 6 foot high retaining wall...the lower 4 feet of intact limestone won't put any significant force on the wall. Two levels of tie rods (say, 2-3 feet from top and bottom) should give you reasonable forces. Both rows should probably be battered - the lower row will probably have to be for installation purposes.
RE: Retaining Wall without heel and toe
Maybe since only a prism of backfill acts one can design for lesser push if as narrow as the effect be accountable. Obviously this contradicts the misconfidence urging to use tiebacks to the then buried rock wall.
To reduce forces for vertical anchors taking moment, one can always widen the foundation (to its costlier expense).
RE: Retaining Wall without heel and toe
Suggest you consider post tensioned anchors. DSI (Dywidag) have an excellent system, and as the bars can be spliced easily, and protected from corrosion with their system, should be usable. You may have to have a wall that is thin at top, thicker at bottom. Do not use any section less than 6" thick.
You may have built his already, so my comments may be redundant.
Regards
Jim Beck, P. Eng.
RE: Retaining Wall without heel and toe
RE: Retaining Wall without heel and toe
Regards...
D. Bruce Nothdurft, MSCE, PE, PG, M.ASCE, etc, etc,...
Principal Engineer/Geologist
Atlantic Geoscience & Engineering
Charlotte, NC
RE: Retaining Wall without heel and toe
RE: Retaining Wall without heel and toe
D. Bruce Nothdurft, MSCE, PE, PG, M.ASCE, etc, etc,...
Principal Engineer/Geologist
Atlantic Geoscience & Engineering
Charlotte, NC
RE: Retaining Wall without heel and toe
I didn't see your 9/9/2003 post until a minute ago; guess I closed that browser panel too quickly. I chuckled - glad someone else gets "fired up" from time to time!
BUT I'm going to conditionally disagree with the following statement,
Mike Simac's footing bearing capacity procedure used for such walls, as published in the NCMA manual, is an exercise in futility as well as evidence of inane thinking.
It is clearly wrong to think of the problem as a bearing capacity problem per se, but one does need to look at the overall (slope) stability of the arrangement. And let's remember that bearing capacity and slope stability have a lot in common.
(You clearly understand the "fine distinction" I'm making, but some readers might not -)
I completely agree with your "inane thinking" comment - looks like fuzzy thinking to me. Like the view one gets from a certain dark, smelly place...
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Retaining Wall without heel and toe
Focht3 and I have had our discussions on the calculations of "bearing capacity" of MSE walls - I really do believe it is a misnomer. However BS 8006 uses this as "bearing capacity" and most follow suit; but interestingly it is usually acceptable to use a factor of safety against the shear failure of 2 rather than 2.5 to 3. My view is that the slope stability concept is better suited to the safety of the structure. With "bearing capacity" - the one side is significantly higher than the other so the ultimate capacity doesn't really take in the 2pi x Su; but the 1pi x Su which is more geared to the slope problem. (Hope I got that right!).
By the way, I would love to get together with some at the Nashville Conference but, alas, I am back in the sub-continent.