Helical Pier Application
Helical Pier Application
(OP)
I’ve attached some project specific information where we would like to use a unique application of the helical pier. I’ve attached more information than necessary as I am really just after the basics and discussing feasibility.
Project Scope:
Our client would like to install a big block segmental wall adjacent to the property line. The low side of the wall is ‘our property’ the adjacent side is the high side. On the high side of the wall there is an existing structure. We have permission to work on the adjacent property and would like to install temporary shoring to install the segmental wall. We do not want to use driving or vibrating required shoring. We would like to use a helical pier that maybe removed when the wall reaches a certain point. We have discussed using either a cantilevered secant pile wall type system with larger shaft diameters or an anchored soldier pile and lagging approach. We discussed this briefly with a contractor (Elite Piering) and they seemed to prefer the anchored soldier pile idea as they were not sure what large sizes were readily available to do a secant pile wall. I should mention that there is bed rock 10’-20’ feet below the bottom of the excavation. However the excavation height is not very tall 6’ +-.
Questions:
1. Do these approaches seem reasonable?
2. Is there a method of analysis/design you would recommend for evaluating the lateral pressure for this type of system. Because these are not very deep I was thinking that using a Broms type method (similar to the California Trenching and Shoring manual) or the FWHA Geotech. Circ. 4 (reese-wang or Broms eqns) would be reasonable.
3. Any general comments?
EIT
www.HowToEngineer.com





RE: Helical Pier Application
EIT
www.HowToEngineer.com
RE: Helical Pier Application
EIT
www.HowToEngineer.com
RE: Helical Pier Application
EIT
www.HowToEngineer.com
RE: Helical Pier Application
I thought you purchased Azizi's "Engineering Design in Geotechnics" last year? All you need are on pages 367-378. But first, you need to get the earth pressure and surcharge envelope from the project geotechnical engineer. If you are the one who has to develop the earth pressure envelop, see Chapter 6. Once you do a one level tieback design by hand, it is easy to program it and move on to 2,3, 4 levels of tiebacks.
For your short exposed heights, you may consider cantilevered soldier beams.
I found Caltrans and FHWA methods to be unnecessarily complex and conservative.
If you want to check your answers with a software, try the #8, "substructural design" at
http://www.dcalc.us/ProgramDescriptions.html - they are great programs and I use them on a weekly basis. Highly recommend them!
Also Google SBWALL, Supportit, TBWALL, PYWALL and Shoring suite.
RE: Helical Pier Application
EIT
www.HowToEngineer.com
RE: Helical Pier Application
RE: Helical Pier Application
EIT
www.HowToEngineer.com
RE: Helical Pier Application
I think the pier will move laterally in the disturbed zone(low passive resistance). With a building directly above I wouldn't take the chance of movement.
RE: Helical Pier Application
I have contacted AB Chance for their thoughts. I will let you know what I find out. So you think it would be best to drill soldier piles or secant wall (as you suggested before in regards to a different post of mine I believe)
EIT
www.HowToEngineer.com
RE: Helical Pier Application
EIT
www.HowToEngineer.com