Influence of pile hammering on existing burieed utilites

[soil1999]

Hello, Does anyone know any formulas that help in evaluating the potential of driving proccess of piles on adjacent buried steel pipelines. Pipelines are from 2 to 4 inches steel pipelines buried at 3 to 5 ft in very soft soil. The piling of the buliding are made of woood (8 to 12 inches)and they are far around 15 to 20 ft from the pipeline. I am using Attwell and Framer (1973) formula that requires pile energy per blow, empirical soil parameter, and source distance, to evaluate the Peak Particle Velocity (PPV). I used this formula for building before in combination with monitoring program.
But I cannot find in the codes ASME or Canadin the permissible value of PPV for undergraound utilitits
Any help or refernce to helpful materials concerning this subject is appreciated. Much appreciated.

 

[Ron]

You are not likely to find limiting criteria as the potential for damage is extremely low.

 

[soil1999]

Ron..what do u mean.. is it the permessible damage is extremely low.. or is it the damage that occurs from this driving activity is extremely low.. if the the later.. how did u judge that.. is it educated guess.. I am trying to base my decision on calculation.. or code requirement..

 

[BigHarvey]

I agree with Ron. You won't find precise limiting criteria for structures for piling activities, less for underground utilities. If you ask the question to utilities owner, they generally answer that they only tolerate a max PPV of 0 !

The only thing you can do is
1) estimate the PPV generated by the rig which is to be used ( Ground Engineering published a good prediction tools for impact hammers in the 90's )
2) compare it to what is tolerated for structures submitted to mining blasting operations

Sensitive structures will admit at least a PPv of 5 mm/sec. if in doubt you can pre-drill a hole larger than the pile down to the level of the utility and then drive the pile. Vibrations induced to the utility will be reduced quite a lot.

 

[msquared48]

For a minute, I thought you said Pureed Utilities, then again, I guess that is not the result you want, so maybe it is relevant.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[soil1999]

BigHarvey

"Sensitive structures will admit at least a PPv of 5 mm/sec"

is it at least or maximum

 

[soil1999]

I am also guessing that I should request from the piling commany the energy applied to the pile by the Impact load of the hammer..this is to be used on the PPV formula above.

 

[Ron]

I was referring to the potential for damage to the pipe from the soil-transmitted vibration.

There are lots of data available on damage potential to building structures related to vibrations, whatever the source. In general, to prevent cosmetic damage to buildings, peak particle velocities (PPV) are limited to less than 0.5 inches per second (IPS).

A steel pipe, even with connections, is much more robust than the items on a building that would be subject to cosmetic damage. That is one of my reasons for my previous statement.

I have monitored vibrations numerous times from pile driving and other sources, checking for building damage during the vibration events.

Some soils attenuate damaging vibrations reasonably well. Yes, vibrations can occur that will damage buildings, foundations, underground utilities and other items in close proximity to the vibration source. This is particularly true of loose sands under buildings on shallow foundations, where even small vibrations can cause additional settlement and building damage. Not the same with a steel pipe, though.

At the distances you noted, and considering that you are using wood pilings (which will attenuate a lot of the vibration from driving and since wood pilings are not usually driven to refusal but to a pre-determined tip elevation, the vibrations don't usually increase much with driving depth), I would not expect damage to the pipe from this activity.

It is much better to monitor the vibrations during the event than it is to try and predict the vibrations by calculation. You are dealing with variable amplitude and frequency through a non-homogeneous material, so your calculable result is probably not much better than a wild-a$$ guess.

 

[ishvaaag]

These worries are but to grow with increased awareness; for example, due to reform to the traffic network at my town the number of buses pasing in front of our 7 stories high condominium has multiplied 5 fold or so; after 1 year in the situation our fuel tank -close in the cellar to the street- has fractured, quite likely on mid-cycle fatigue straining. And relevant ppv must be moderate since vibration at the second floor must have typically amplitud less of 1 mm or so.

These things do not affect only mechanical things; it is typical after the local annual fair ("Fiestas del Pilar de Zaragoza") to have a number of appliances "toasted" by the imbalances caused to the electrical network to make place for the temporary displays. Total o partial casualties this year in the aftermath of these have been Digital TV box, DVD recorder, dishwasher and this same computer showing some BSODs (Blue Screen of Death) -never seen before- every 2 days or so.

 

[BigHarvey]

the 5 mm/s criterion is a maximum PPV, and it is the lowest criterion I know.