Retaining Wall / Bulkhead Anchor Location

[craigmcg]

I have a question regarding the required anchor setback on general retaining walls or bulkheads. Perhaps someone here has some insight. I already know the following:

Lets assume an anchored sheet pile bulkhead. The location of a bulkhead anchor must account for two sliding planes to ensure 100% efficiency. The first (A1) is angled 45+phi/2 from the sheet pile toe and the second (A2) is angled at phi. Full passive resistance on the anchor will be obtained if the anchor's passive failure plane does not intersect with A2. Secondly, no additional load will be transferred to the bulkhead if the anchor is situated behind A2.

There seems to be two schools of thought for the second scenario and I cannot find a definitive answer on which is right. Some references (Bowles) imply that the top of the anchor should be behind A2 for full efficiency while others (Arbed Sheet Pile Design Manual, Kranz(1940)) specifically state that the base of the anchor should be used instead.

Does anybody have any relevant references to this question? I apologize in advance if anything presented here is unclear.

Thanks.

 

[PEinc]

I locate the deadman anchor so that the active failure plane of the wall (at 45 + phi/2 above horizontal) does not intersect the passive failure plane which extends up from the bottom of the deadman (at 45-phi/2 above horizontal). If they do not intersect, I assume full strength for the deadman and no load on the wall.