Effect of pre-drilling on the capacity of skin friction piles?
Effect of pre-drilling on the capacity of skin friction piles?
(OP)
I'm looking to find any information available on the effect of pre-drilling on the capacity of skin friction piles.
How do you quantify how much the pre-drill will affect the capacity? Are there any rules of thumb of regarding how small a pre-drill needs to be for the effects to be negligible? Are there any good papers discussing this topic?
Any information is greatly appreciated!
How do you quantify how much the pre-drill will affect the capacity? Are there any rules of thumb of regarding how small a pre-drill needs to be for the effects to be negligible? Are there any good papers discussing this topic?
Any information is greatly appreciated!





RE: Effect of pre-drilling on the capacity of skin friction piles?
There could also be adverse affects of soil disturbance that reduces the positive pressure.
I believe the IBC requires load tests to be performed on driven friction piles, specifically due to pre-excavation; I always specify it. For design, I assume that there are adverse effects, and I do the following "ad-libbing": I multiply the friction coefficient between the soil and the pile by a ratio of the at-rest pressure coefficient divided by the passive coefficient. For example, if the at-rest coefficient is 0.5 and the passive is 2.0, you have 0.25, so I assume that the friction pile coefficient is 25% of the value used if there were no pre-excavation.
This is what happens when we were not given a budget for geotech analysis. Again, the important part is to have the piles load tested per IBC. Hope that helps a bit.
If I got paid for every hour I worked, I'd be a wealthy man.
RE: Effect of pre-drilling on the capacity of skin friction piles?
My experience is mainly for by passing obstructions and also to get a minimum penetration into very hard material such as rock. In neither case is side friction an issue.
RE: Effect of pre-drilling on the capacity of skin friction piles?
RE: Effect of pre-drilling on the capacity of skin friction piles?
RE: Effect of pre-drilling on the capacity of skin friction piles?
Seems like at some point, if the pre-drill is small enough, it's effect on capacity would be negligible. No?
RE: Effect of pre-drilling on the capacity of skin friction piles?