Soldier Pile Wall w/ Surcharge
Soldier Pile Wall w/ Surcharge
(OP)
I'm designing a soldier pile and lagging retaining wall. There is an existing building (2 story house) that will be near the wall (1 to 2ft from the back). I plan to design the wall with an appropriate surcharge from the house foundation and limit the deflection of the top of the wall to reduce potential settlement. What should the maximum settlement be? And also, is there any need for underpinning in addition to the wall and/or should I sequence the drilling operation to alternate piles (i.e., every other pile installed first) to reduce the settlement potential?





RE: Soldier Pile Wall w/ Surcharge
What type of lagging were you thinking of using and how do you think it will be installed?
www.PeirceEngineering.com
RE: Soldier Pile Wall w/ Surcharge
Alternately, if I underpin, how deep do I need to go below the new excavation? The underpinning concrete column is designed for lateral loading in addition to vertical, so I would still need to go deep enough to get enough passive pressure, right? Also, are underpinning pits typically reinforced? An underpinning pit is essentially a cantilevered, reinforced retaining wall with a vertical load at the top, correct?
I've been looking for a good design example of underpinning, but they seem sparse.
Thanks for your input.
RE: Soldier Pile Wall w/ Surcharge
How deep is the excavation going to be?
Does the same person/company own the house as is performing the excavation?
What kind of construction is the existing house?
There will be damage to the house. Underpinning and/or shoring can reduce that damage, but some damage will occur.
Mike Lambert
RE: Soldier Pile Wall w/ Surcharge
www.PeirceEngineering.com
RE: Soldier Pile Wall w/ Surcharge
The soil is sandy silt/silty sand with SPT blow counts between 49 and 96 blows per foot, between zero and ten feet below grade. The excavation will be about 10-11 feet. Another issue the geotech brought up regarding helical piers is that we may get refusal before getting to 10 or 11 feet because of density of material. I'm not sure this would actually be a problem either.
In answer to other questions from GeoPave, the house is a two story wood framed building. Home owners have hired a contractor to do this and other work.
RE: Soldier Pile Wall w/ Surcharge
As for any interior footings, pin pile would probably not work, meaning re-shimming the footings as settlement occurred.
Mike McCann, PE, SE (WA)
RE: Soldier Pile Wall w/ Surcharge
If the excavation is 10 to 11 feet, cantilevered soldier beams will deflect unless they are very stiff and the soil is very dense. Helical piers will add little or nothing for lateral support.
If you are worried about the condition of the soil behind the lagging, you may have the wrong contractor.
www.PeirceEngineering.com
RE: Soldier Pile Wall w/ Surcharge
As a bonus, you can have the shotcrete sculpted like they do at Disneyland.
Bob
RE: Soldier Pile Wall w/ Surcharge
Pin piles can take horizontal lateral loads? I was thinking only helical could be used in such case. Do you know where design values would be located?
You touched on this briefly and that is the idea of the building now having differential settlement if only underpinning the adjacent side.
Does anyone know if this is typically a problem? Is there a certain age of the structure where this is generally not a problem? Or do you typically underpin a certain extent (depth of the excavation) as mentioned. Should/does the geotech generally address this?
In this case there could be an issue with crossing the property line with the 'tiebacks'. But I suppose if you're going to underpin it then there probably is not an issue. I wonder how many cases there are where underpinning is the better solution but there is a property line issue so other type of bracing is used instead...
Thanks
EIT
www.HowToEngineer.com
RE: Soldier Pile Wall w/ Surcharge
RE: Soldier Pile Wall w/ Surcharge
Pin Piles are small diameter high capacity drilled and grouted piles also called minipiles or micropiles.
RE: Soldier Pile Wall w/ Surcharge
EIT
www.HowToEngineer.com
RE: Soldier Pile Wall w/ Surcharge
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RE: Soldier Pile Wall w/ Surcharge
RE: Soldier Pile Wall w/ Surcharge
it is important to do alternating piles as mentioned above so the jet grouted soil can harden.