oil contamination in soil for offshore pile design

[saeed_1980]

During drilling a 110m offshore borehole, the existence of soil layers containing active hydrocarbon materials was investigated which a phenomenon is almost rare in geotechnical studies (the depth 60m up to end of borehole). The in-situ CPTU, sampling and experimental tests on undisturbed soil was performed.
Considering the limitations in the standards and similar experiences regarding soil contaminated with crude oil:
• Are there any standards which in defined soil-crude oil interaction in geotechnics?
• How to utilize the reduction factor on deep foundation design parameters including ultimate capacity, P-y, T-z, Q-z and SRD curves? The pile is OD= 60” thickness= 1” length= 85m and some part of pile will be penetrated in oily contaminated soil.
• What is the effect of contamination to mobilize shaft resistance in piles?

 

[EireChch]

If its very oily and contaminated (whats very oily?) I would imagine that it is reducing the strength of the material. But how do you quantify this. You run tests on the samples you have, but then the next question is, are the samples representative of the material.

In light of that you could just ignore skin friction contribution from this layer.