backfilling at low temperatures_more_bigH

[emrah26teng]

It is a tank foundation with a exc. bottom dia as 45m and depth about 4.5 meters. I am planning to use a loose soil layer as a blanket not to freeze the layer already compacted.
Water table is 1m below existing grade elevation, so I will be running a dewatering system as well.
The material is natural borrow pit sand with 2-3% water content. If you can advise with a general application it may help me as well,Thank you.

 

[ishvaaag]

Study if the pores are enough to take the volume growth of the water (likely yes for most sandy soils). You are as well attempting to protect what compacted with temporary loose sand, then the thickness to which freeze penetrates as average should be investigated for the expected ranges of temperatures. A further defence would be to forbid push attaining initially the full strength by putting against the back of the wall thrugh some compresible layer, maybe just some thin neoprene or tick layer. A (thick) polyestirene interposed layer will surely lead to local settlement midterm, so I think is not advisable.

Also, you may fill all except the most inmediate section to the wall. You so forfeit this way any effects on the wall of the freeze on any soil of this first stage. Then you fill and compact the ring, that from its circular nature will attempt expansion rather than compression against the back of the wall. But if it buckles on freezing, at some point will generate a point load on your wall. So it may be interesting to as well radially divide the inner ring, to allow for any expansion effect be accommodated on the circular segments so formed. Finally, you fill the remaining cuts. Divide and win.