Soil Dessication
Soil Dessication
(OP)
Does anyone have information regarding the change in moisture content over time with soils located within a building?
See thread: thread507-323989: Wrong Voidform
thanks, Dik
See thread: thread507-323989: Wrong Voidform
thanks, Dik





RE: Soil Dessication
Dessication will occur by one or both of two common methods...the first is lack of recharge because of the impervious nature of the construction above. The second is reduction of moisture by vegetation, particularly larger trees as they grow.
The impact of lack of recharge is related to the footprint size of the building. Obviously, the larger the building footprint, the more likely little or no recharge will occur near the center, thus more drying near the center. The lateral permeability of the soil will typically be less than the vertical permeability, so unless there is cross-flow drainage at the near surface level, dessication will occur.
Recharge piping under the building could be considered, assuming the construction occurred when the soil was in a swollen state. If not, recharge piping would likely cause swelling thus engaging the voidform to some degree. Recharge sources could be roof drains or surface drainage. A moisture content monitoring system can be employed to control the amount of recharge.
As for the vegetation, that can be controlled as long as you don't get into a fight with the landscape architect! A chainsaw usually cures that issue!
RE: Soil Dessication
I've not been able to obtain information on the dessication within a building although I've seen it and know it happens. I also don't have information on the pressures caused by swelling clays and I suspect this varies with the clay.
Dik
RE: Soil Dessication
Attached is a BRE paper on shrinkage of clays under low rise buildings. Hopefully something in there you can use.
RE: Soil Dessication
Dik
RE: Soil Dessication
RE: Soil Dessication
Dik
RE: Soil Dessication
RE: Soil Dessication
I submitted my report on the project this AM and it appears that everyone is 'happy' with it... Found out, after the fact, that the reason the Contractor used the plastic void was because 2 prior cardboard attempts had 'soaked up, some liquid sunshine... I had noted in the report that the use of plastic was often to prevent this type of occurrance.
Dik
RE: Soil Dessication
RE: Soil Dessication
f-d
¡papá gordo ain’t no madre flaca!
RE: Soil Dessication
RE: Soil Dessication
I've included in the report that because we haven't experienced drought conditions, it's unlikely that the soil is in a 'pre-shrunken' state.
Is the greater horizontal movement of water to be anticipated for our varved clays (I realise you are not in our area).
Dik
RE: Soil Dessication
Dik
RE: Soil Dessication
Varved clays are more likley to have the 10 fold distinction between horizontal and vertical permeability.
Yeah, I'm in Virginia, but I've worked all over the country, except for Texas 'cause it's too hot!!!!!!
f-d
¡papá gordo ain’t no madre flaca!
RE: Soil Dessication
Dik