Soil freezes naturally all of the time. It is at this point that dirt work usually stops.
Occasionally soil is intentionally frozen to improve its structural properties. This process has been used notably in Boston's Big Dig and the Fukushima Daiichi nuclear plant.
When soil is intentionally frozen so that tunnels or vertical shafts can be excavated, the structural properties of the frozen soil are important. It would seem logical that the frozen water would help to stiffen the soil, but how are the actual structural properties of the soil determined?
- Do all frozen soils end up with the same properties? i.e. the presence of ice controls the properties.
- Are the frozen soil properties related to the unfrozen soil properties in any way?