Monitoring During Pile Driving 2

[GeoGrouting]

I would appreciate advice on monitoring options that a geotechnical engineer should take for a building located about 9 ft from the piles during driving about 60 ft steel pile pies in very soft silty clayey materials.

 

[Ron]

Monitor all vibrations. Set triggers with alarms for exceeding critical vibrations.

Do a very detailed pre-construction survey of the existing building and document all visible defects, cracks, anomalies and issues that could be affected or influenced by adjacent construction activity. Use still photos and video for the survey. Install crack monitors on existing cracks and clearly mark the ends of cracks to see if they propagate further after the activities.

 

[moe333]

May also want to take some accurate elevation shots with a benchmark far enough away to avoid disturbance.

 

[GeoGrouting]

The buildings are one storey industrial workshops and there are 12 piles for a single pile cap foundation of 3x3 m2. How could I monitor vibration. Do you mean to use a Blastmate. Seems too much.

 

[BigH]

Further to Ron's good advice on detailed pre-construction survey of existing structure, I might suggest that a third non-interested party attend to attest. A firm or individual not associated with the project so that there is an independent confirmation - you know that even with a detailed survey, the owner of the adjacent building is still going to "scream".

 

[Ron]

Vibration monitoring is done with a portable seismograph and accelerometers calibrated in the expected vibration range of the activity.

Not sure where you are located, but these can be rented easily in the US and Canada.

Agree with BigH on the third-party observation. Have a testing laboratory experienced in this type of work do the whole thing.

 

[PEinc]

I also like to make sure that the adjacent property owners know I have done a preconstruction survey and will be monitoring the structures. This helps keep them honest about making damage claims.

http://www.PeirceEngineering.com

 

[EBSEngineering]

Have you considered a helical piers, say like Chance? We have used these very successfully in places where there are vibration concerns and there is no need to monitor the adjacent building then. Helical piers do not cause vibration when installed and can acheive some pretty high loads, depending on the soils. The helical pier contractors usually have pretty small equipment so access is typically not an issue.

Otherwise you could try OSMOS structural monitoring system. Used it before too and has continuous instant feedback on vibrations caused.

 

[BigH]

PEinc - wouldn't they know anyway - else how can you get on their property? Agree that there needs to be a lot of transparency - but not matter what - in the USA - be prepared for lawsuits regardless . . . too many lawyers.

 

[oldestguy]

I find a simple crack monitoring method can be done, (if the owner ok's it) is with a pencil and ruler draw lines across the crack. Then, place a crossing mark on each side, measured exactly a given distance apart, generally 2" spacing works.

Then your periodic readings for each show the spacing of the marks, as well as the offset of the line at the crack, should that happen.

Locating these where they are not affected by other things, such as storage in front, etc. and can be read conveniently.

 

[PEinc]

I do the same. It's a lot cheaper than buying crack monitors.

http://www.PeirceEngineering.com