Frost jacking of driven steel pipe piles

[claytill]

The design of Lightly loaded unheated structures that are supported by driven steel pipe piles is often governed by resistance to frost jacking. I have often seen Geotechnical reports state that piles should be driven a minimum of 6m. The same reports typically give an adhesion value for frost jacking ranging between 65 and 100 kPa which are to be considered for design.

If one uses a FoS of 2.5, the 6m pile depth is insufficient.
My questions are for steel piles driven to refusal in silty clay till in Alberta with a shallow GWT (1 to 3 m)as follows:

1. What is an acceptable FoS for frost jacking?

2. Can you point me to any literature or studies relating to this other than CFEM?

3. Any general comments on peoples experience with this from a structural or geotechnical staandpoint.

 

[CarlB]

My experience is the recommended embedment is based more on "rules of thumb" and local practice rather than known adhesion values, etc. It often comes down to "total embedment of 3 times the active layer thickness(design frost depth)".


Some guidance in

http://www.wbdg.org/ccb/DOD/UFC/ufc_3_130_04.pdf