Pile Driving Near Recently Poured Pile Cap

[swearingen]

As the title says, we have a client that will continue pile driving near a recently poured pile cap. What time/vibration criteria should we use to limit the pile driving activities? DOTD specs limit particle wave velocities to 2.0 in the vicinity of industrial structures (our case), but are there looser numbers available for a pile cap alone? Also, we are considering limiting driving until after the cap reaches 70% strength (we will break cylinders at 3, 5, and 7 days to make sure).

Comments? Guidance?

Thanks in advance!


-5^2 = -25 ;-)

http://www.eng-tips.com/supportus.cfm

 

[Ron]

Limiting driving until you reach 70% strength is a good practice. In general, if your pile placement is at least 3 pile diameters away, it shouldn't have much effect. Florida Atlantic University did a study on this about 15 years ago. I'll see if I can find my copy of the report.



A Great Place For Engineers to Help Engineers

Follow me there.....

 

[BridgeSmith]

For concrete bridge deck overlays where we do half the bridge at a time, with traffic on the other side, we reduce the speed of the traffic (to limit vibrations) for 24 hours, just until the concrete is no longer in its plastic state. Granted, it's typically a high strength mix that likely gains strength faster than 'normal' concrete, but OTOH, we're also fairly conservative and cautious when it comes to making sure those overlays bond well to the existing concrete deck. I wouldn't be nearly as cautious with a pile cap, where the bond between the concrete and the pile isn't critical.

 

[MTNClimber]

When driving very close to fresh concrete, 24 hours after placement is complete is what I've used before. Based on research (there's plenty out there that can be found by using google) that time window can be shortened to time for final set and keeping vibrations under 2ips. It would have to be a REAL jam for me to lower the time from 24 hours. Usually I'll tell the contractor to go work on the other side of site for a day and next time, coordinate better with the other contractors.

 

[swearingen]

Thanks for the replies!

Ron, I'm very interested in getting a copy of that report if you can find it.


-5^2 = -25 ;-)

http://www.eng-tips.com/supportus.cfm

 

[MTNClimber]

Here's one of many online.