I am being asked to provide a recommended ADFREEZE stress for a drill shaft supporting a solar panel system in Southern New Jersey. I can't seem to find any good information on estimating ADFREEZE stresses for different soil types in contact with concrete. Any recommendations?
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ADFREEZE
- Thread starter John_C
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geotechguy1
Civil/Environmental
This is the blurb on the topic in the Canadian Foundation Engineering Manual (4th edition):
"Soil in contact with shallow foundations can freeze to the foundation, developing a substantial adfreeze bond.
Backfill soil that is frost susceptible can heave and transmit uplift forces to the foundation. Spread footings normally
have sufficient uplift resistance from their expanded base to resist heave, but the structural design of the wallfooting
connection must be sufficient to transmit any load applied through adfreeze. Average adfreeze bond stresses,
determined from field experiments, typically range from 65 kPa for fine-grained soils frozen to wood or concrete to
100 kPa for fine-grained soils frozen to steel (Penner, 1974). Design adfreeze bonds for saturated gravel frozen to
steel piles can be estimated at 150 kPa (Penner and Goodrich, 1983). The most severe uplift conditions can occur
where frost penetrates through frost stable gravel fill into highly frost susceptible soils surrounding a foundation.
These conditions result in a heaving situation with maximum adfreeze bond stress and have been known to jack Hpiles
driven to depths in the order of 13 m (Hayley, 1988).
It is good practice to backfill against foundations with non-frost susceptible soil. Provision should be made for
drainage around the foundation perimeter, below the maximum depth of frost penetration. The granular backfill
should be capped with less permeable soil and a surface grade provided to shed runoff before it enters the backfill"
"Soil in contact with shallow foundations can freeze to the foundation, developing a substantial adfreeze bond.
Backfill soil that is frost susceptible can heave and transmit uplift forces to the foundation. Spread footings normally
have sufficient uplift resistance from their expanded base to resist heave, but the structural design of the wallfooting
connection must be sufficient to transmit any load applied through adfreeze. Average adfreeze bond stresses,
determined from field experiments, typically range from 65 kPa for fine-grained soils frozen to wood or concrete to
100 kPa for fine-grained soils frozen to steel (Penner, 1974). Design adfreeze bonds for saturated gravel frozen to
steel piles can be estimated at 150 kPa (Penner and Goodrich, 1983). The most severe uplift conditions can occur
where frost penetrates through frost stable gravel fill into highly frost susceptible soils surrounding a foundation.
These conditions result in a heaving situation with maximum adfreeze bond stress and have been known to jack Hpiles
driven to depths in the order of 13 m (Hayley, 1988).
It is good practice to backfill against foundations with non-frost susceptible soil. Provision should be made for
drainage around the foundation perimeter, below the maximum depth of frost penetration. The granular backfill
should be capped with less permeable soil and a surface grade provided to shed runoff before it enters the backfill"
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