Monday, August 26, 2013

Inside and outside the circle




Here's a question, partly related to my thoughts about using string to define a circle. 

In the case of building the circular structure shown in this photo (which I've been documenting for the last week or so) is anything improved structurally by actually having a 'defined' outside cylindrical surface,with stone material separately back-filled after?
 Example B


  


Or, might it be just as structural, or perhaps better, to 'morph' the outer stonework into the same back-fill material (leaving the outside shaggy) so that, in effect, it has no outside dimensions at all?   Example A

12 comments:

  1. There's an article by physicist Theo Schmidt which hints to this aspect of 'backfilling/retaining walls, in the soon to be issued stonechat 29. This sort of mentions that adding geotextile to a retaining wall weakens it in respect of separating it from the bank and so there is no binding. My gut thoughts would be that something similar happens where the back is defined rather than merging. It would help explain why single skin retaining walls are not necessarily weak... Of course its walling theory so nothing is 100% for example by defining the wall you might actually make it stronger which might negate/reduce the weakening...
    SEan

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    1. Good thoughts. Thank you Sean. Can't wait to read your article in stonechat .

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  2. I would imagine that having a 'shaggy' exterior wall would allow for knitting with the backfill and thus making the stones more tightly connected. Would freeze and thaw be of any concern with having the exterior wall independant of the fill? Would an earth tremor stop at a non connected wall? I know that when using the dreaded mortar in repairs a shaggy edge makes for more contact in adherence as does a torn paper edge rather than a clean cut works with glue.
    Good question. I hope there is some feedback. I will try to find any documentation on it.

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    1. Thanks Anon. In talking about this with others it was suggested the a separation of structure and backfill would be better if there were any movement within the backfill. Let me know what you find out in your research

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  3. Just curious.
    Would the work go faster if the outer wall need no definition?
    Maybe do half and half. After a few centuries some proof
    of an answer might 'surface'.
    I hope you are paid long before that time.
    Looking good guys.
    Jim Grandy

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  4. Thanks Jim. We have decided to go hole hog with the separate defined outside wall. No one will know if the other way would have lasted 200 years longer

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    1. Would the task take less time if you didn't define the outer wall?
      Hank

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  6. I think it is important to build the exterior walls so that the structure stands on its own If only the interior walls were built any shift in the fill would likely show and cause damage to the structure. With the exterior walls built movement/settling of the fill would not affect the structure. Then there is the roof. Just fill would not provide a strong enough buttress. Christopher Barclay

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