ABTSGeoScience
Geotechnical
- Jul 30, 2024
- 5
I have a query, I am new here but I am a geotechnical engineer that has been practicing for near 30 years. I have historically not done many investigations for swimming pools, but it seems locally that I am getting more and more requests for either pre-construction investigations or forensic studies for pools that have moved.
I work in an area of the country where there is a large formation of smectite, over-consolidated Fat Clay (CH), very high PI, slickensided, etc. (nasty stuff). Aside from the obvious issues of Shrink/Swell movement, this clay formation is also notorious for rebound as a result in reduction of overburden stress. I have looked at several swimming pools as of late where the deep end had risen several inches relative to the shallow end, obviously because of a greater reduction in overburden stress due removal of more clay being replaced with water. This rebound effect is a very, very slow process and can take years to develop. There really isn't an effective preconstruction mitigation for this of which I am aware. Short of having to elevate the pool off-grade on piers with a void beneath it was to recommend thickening the concrete of the pool bottom (essentially pouring a concrete deadman) to offset the difference in stress reduction. Has anyone ever tried something like this or had to address a swimming pool with this kind of potential problem ?
I work in an area of the country where there is a large formation of smectite, over-consolidated Fat Clay (CH), very high PI, slickensided, etc. (nasty stuff). Aside from the obvious issues of Shrink/Swell movement, this clay formation is also notorious for rebound as a result in reduction of overburden stress. I have looked at several swimming pools as of late where the deep end had risen several inches relative to the shallow end, obviously because of a greater reduction in overburden stress due removal of more clay being replaced with water. This rebound effect is a very, very slow process and can take years to develop. There really isn't an effective preconstruction mitigation for this of which I am aware. Short of having to elevate the pool off-grade on piers with a void beneath it was to recommend thickening the concrete of the pool bottom (essentially pouring a concrete deadman) to offset the difference in stress reduction. Has anyone ever tried something like this or had to address a swimming pool with this kind of potential problem ?