Determination of Soil Settlement

[nana1971]

I have just removed a section of very impermable clay that was 1.5m deep by 150 square meters. This was backfilled with topsoil and gravel to improve the permeability and tests were carried out to determine how long it would take a specific volume of water to soak away. This test was regulated under certain conditions and they all passed. My only issue now is that I am trying to determine how much if any settlement will occur within the soil mass. It will not be loaded and I assume there must be some kind of formulae that can be used to determine this settlement.

 

[BigH]

If this is for a septic field, why need to know settlement - sure it will settle with time especially with topsoil being used. Just "top it up" as needed; may cause homeowner to redo his lawn one or two times. The self-settlement will really depend on how well you compacted your topsoil/gravel fill. If loose, like I presume it is, it will settle more than if compacted; but then if compacted, you probably wouldn't get the seepage. Don't forget that as it does settle, the seepage flow will become slower.

 

[nana1971]

Thanks for your reply BigH. You are correct in stating that the soil will settle over time and that seepage will become slower. However my problem is that I need to prove how much settlement will take place and how much the seepage will slow down by. Is there any calculations that can be done to determine this.


Regards
Nana1971

 

[Focht3]

Hmmm,

Not really. Too many factors to consider. If this is a critical consideration, then you will need to increase the size of your drain field to allow for permeability reduction over time. Remember that biological clogging of the pore space may be a bigger (and more immediate) factor than soil settlement -



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