Structural Design of Push Pier Systems

[Forensic74]

I am researching the standard protocol for the design of residential push pier stabilization systems. If you have experience in this, how have you seen the process typically go? I.e., did the owner directly retain their own SE to come up with a design? Or does the foundation contractor retain the SE? At what point does a geotechnical engineer become involved? What exactly is the SE designing and specifying to the contractor? Any experiences are appreciated.

 

[Agent666]

Not familiar with the systems, but perhaps the supplier of these systems will be the most experienced in how they see a project being delivered in the most efficient manner.

Try discussing it with them, I suspect most of these types of suppliers have their own engineers (or technical staff) and are keen for people to specify their product so they win more work, so are generally quite helpful/invested in getting the most out of it for their customers.

 

[XR250]

Most contractors around here have switched to helical piers. I have designed both for the customer or the contractor. You should not need a geo-tech as the systems are based on installed capacity read from pressure gages in the hydraulics. I think the problems installers haver had with push piers is not having enough dead weight to actually push them in sufficiently. One contractor I know will only use them on 2 story houses with brick so he has alot of dead load but he has also switched to mainly helicals. Around here, most engineers, just call out a capacity per pier and the spacing - (typically 5-6 ft. by rule of thumb) and show a typical cross section of installation. You also have to be careful not to show too many piers on one side of the footing as it can rotate so some engineering judgement has to be used there.

 

[emmgjld]

Let's see;
Determine reason for underpinning.
Determine what the soils profile is, - support strata - installation problems.
Determine access on the site and convenience for the client.
Determine what is reasonably available. Helicals? Push piles? Micro piles? Compaction Grouting? other?
Which methods can be installed due to access, installation problems, support capacity, geotechnical requirements, etc?
What is the existing foundation capable of withstanding during the repair installation & adjustment?
In my case, I typically see residential and small commercial foundation system requiring underpinning element spacings ranging from 4 feet to 18 feet. The product engineers usually go for the 4' to 6' spacing along foundation walls and do not seem to dare step out of that zone. If I can confirm the foundation is capable of more spacing, that is usually what I design.