Pile Driving Vibrations
Pile Driving Vibrations
(OP)
Piles will be driven within 10 to 25 ft of existing building. It is likely that vibrations from the pile driving will exceed allowable levels. Besides drilling the piles in, does anyone have any proven methods for driving the piles and keeping the vibrations to acceptable limits? Obviously, I do not want to damage the buildings but I also want a method that works so that the contractor does not have to stop because of vibration concerns. I have seen options such as drilling a casing to a predetermined depth (seems arbitrary), removing the soil, and then driving the pile. How effective is this technique? Any help?





RE: Pile Driving Vibrations
RE: Pile Driving Vibrations
RE: Pile Driving Vibrations
RE: Pile Driving Vibrations
I’ve also seen blasting the foundations of a draft tube inside an operating hydroelectric plant. We just shut down the first couple of generators monitored the velocities. A lot of facilities are more resistant to vibration than you might think.
I’ve driven piles near fresh concrete and we used a blaster’s accelerometer. We arbitrarily set the maximum velocity at one half to one third of the legal maximum for blasting operations near buildings. I cannot remember what the numbers are but any blaster could be able to tell you. (It was a while ago and they tell me that memory is the second thing to go, I forget what’s first.)
Could you try driving one pile and check just what vibrations are caused and what are acceptable?
Rick Kitson MBA P.Eng
Construction Project Management
From conception to completion
www.kitsonengineering.com
RE: Pile Driving Vibrations
Some folks just shudder at the thought of those pile being driven anywhere near them.
RE: Pile Driving Vibrations
Scroll down to CBD(Canadian Building Digest) #63 on balsting effects on buildings.
Rick Kitson MBA P.Eng
Construction Project Management
From conception to completion
www.kitsonengineering.com
RE: Pile Driving Vibrations
I'm also looking for a copy of the Lukas & Gill paper on vibrations. Could you fax me a copy? We are having some controversy with potential vibrations to an adjacent structure in SF, CA. Fax 415-436-9077.
Thanks
RE: Pile Driving Vibrations
RE: Pile Driving Vibrations
I know it doesn't answer your question, but its a little helpful advice.
RE: Pile Driving Vibrations
Structural hairline cracking (75 microns or less) does not start occuring in concrete or mortor until about 6 inches/second or more with low frequency (below 20 hertz).
Cosmetic damage, such as nail pops in sheetrock, etc can start to occur around 4.0 ips depending on construction and vibration frequency.
I have been monitoring blasting and pile driving for many years and have never seen any real damage from either. Its more annoying then anything. Pile driving is much more annoying then blasting.
Remember, the closer to the structure, the higher the limit can be because frequency will be higher. When blasting in Manhattan, we sometimes are given limits of 3 - 4 ips depending on structure construction. The higher the frequency with low ppv = lower displacement.
Also, limits are like speed limits. Just becuase they are exceeded doesn't mean there will be damage. Especially with a low limit of 1 ips.
You can convert to acceleration by using the following formula:
(2pi (ppv)(hz)/386.4 = a
Displacement is the key, so if frequency is high with a low ppv, displacement is low. In pile driving, frequency is normally low (that's why its more instrusive to nieghbors), but there isn't much energy in the wave, so it attenuates quickly and is unlikely to cause serious problems.
Displacment = ppv/(2pi)(freq).
I hope my rambling helps.
Frank Lucca M.I.Exp.E.
www.terradinamica.com
RE: Pile Driving Vibrations
Why would blasting limits be higher than pile driving limits? From your last paragraph, the opposite would seem to be the case.
RE: Pile Driving Vibrations
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Pile Driving Vibrations
RE: Pile Driving Vibrations
Thanks guys!
Frank Lucca M.I.Exp.E.
www.terradinamica.com
RE: Pile Driving Vibrations
RE: Pile Driving Vibrations
I beleive the vibrations from driving or other machine bases can be intercepted or dampened before they reach an adjucent structure or foundation by using certain approaches. One of them could be using a cutoff trench to desired depth. The trench could be empty or filled with a bentonite slurry. I remember to have seen a study like this in Barkan - Dynamics Machines and Bases.
RE: Pile Driving Vibrations
RE: Pile Driving Vibrations
You can also go to the Florida DOT website and get their criteria for limitations of vibration to prevent damage.
RE: Pile Driving Vibrations
The cut-off trench posted above is ok, but more difficult to execute properly.
Regarding effects of vibration, one resource I have used is the intro to FHWA Dynamic Compaction (download at http://www.fhwa.dot.gov/bridge/geopub.htm, scroll down to Geotechnical Engineering Circulars No.1) and NAVFAC DM 7.3 (I think a free down load is at vulcan hammer)which references some of that described above.
RE: Pile Driving Vibrations
So this begs the question, what type of soil are you driving into? High plastic clay, silt, Till, clay shale, shale, weathered sandstone, granite?? Where I'm from, most of the piles have 20' embedment depths, however, that varies with the type of soil and where you are at (ie - northern Canada has adfreeze/frost jacking concerns and Florida probably doesn't have to worry about this).