Pouring Pile Caps near Piles Being Driven

[vandede427]

I need to provide the GC with a recommendation on the minimum distance between a pile cap being formed/poured/cured and the pile driving rig actively driving piles.

I've been provided with vibration monitoring results based on 25' intervals away from the rig. The PPV (peak particle velociy) is 0.2 inches/second for 25' and 50' distances and 0.05 inches/second for 75' and 100' distances.

Other info:
site - north shore of Lake Pontchartrain, LA
piles - 40' deep timber piles - 25 ton capacity
soil - typically stiff to very stiff clay
caps - 3000 psi concrete
hammer - 5000 lb hammer, 15000 ft-lb's striking energy, 60 blows/second

My gut feeling before the vibration monitoring results came out was 50'-100'. I'm thinking 75' based on the vibration results. But I'd like to have some actual scientific basis to make this recommendation, not just a feel good / rule of thumb / gut feeling.

 

[dik]

There can be a problem if the previously driven pile moves and has to be re-driven... not uncommon.

Dik

 

[Ron]

This is generally not an issue. Florida Atlantic University or Florida International University (can't remember which) did a study about 10 years ago on the effects of pile driving vibrations on the proximity of new concrete placement. The result was essentially no affect on newly placed concrete that was more than 3 pile diameters from the pile being driven.