Econmic Design?
Econmic Design?
(OP)
I find that designs produced by Civil / Structural Engineers are more and more being scrutinised and commented on by project engineers / value engineers etc. I give an example below:
In structures under light axial load and high uni-directional moment like retaining walls where piling is appropriate, I have always provided 2 rows of piles - one for tension and one for compression. See attached Fig 1.
Now I am being asked why not do away with compression pile and provide tension pile only. Compression being resisted by bearing on soil. See attached Fig 2.
I have never seen this single row pile design before and instinctively resist it. But I will be interested if any of you have come across this proposal on grounds of economy?
In structures under light axial load and high uni-directional moment like retaining walls where piling is appropriate, I have always provided 2 rows of piles - one for tension and one for compression. See attached Fig 1.
Now I am being asked why not do away with compression pile and provide tension pile only. Compression being resisted by bearing on soil. See attached Fig 2.
I have never seen this single row pile design before and instinctively resist it. But I will be interested if any of you have come across this proposal on grounds of economy?






RE: Econmic Design?
Is the retaining wall subject to high surchage loads and what are the typical retaining heights. In my part of the world, we would try to get away with no piles and size the footing to resist overturning.
RE: Econmic Design?
The height of the wall about 7-8 m. Surcharge 10 kN/m2.
Whether to use piles or not depends on soil condition below the base. If soil is poor, you will have to pile.
RE: Econmic Design?
I don't know much about statistics, but I do know that if something has a 50-50 chance of going wrong, 9 times out of 10 it will.
RE: Econmic Design?
RE: Econmic Design?
It seems that you will never reccommend a piled base retaining wall.
RE: Econmic Design?
RE: Econmic Design?
As an example, if your soil, upon which the toe of the footing rest, settles, then all that will happen is a simple rotation of the footing about the supposed tension pile. The tension pile will never see the actual vertical tension force it is deigned for. Ultimately the wall will fail.
Poor soil conditions and the adverse effects of them are the reason pile foundations are used with highway agencies. Sure they could, in some situations, use different foudnations but the issue of settlement and the problems emanating from that are often costly once traffic is allowed on the facility that no one wants to get back in there to fix anything.
Often times those espousing alternates and value engineering don't really understand the principles of engineering to begin with.
Regards,
![[pipe] pipe](https://www.tipmaster.com/images/pipe.gif)
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RE: Econmic Design?
BA
RE: Econmic Design?
Are permanant tiebacks a possibility?