Designing a non-typical retaining wall

[StruKturdg]

How does one go about designing a retaining wall that does not have a foundation. I have no room to put a strip footing. I have to design a wall that retains about 6' of dirt and a three story brick home about 8' away. I am having a Hydro-Excavation crew come out and dig me a trench, and they can hydro however deep I need it, but I am kind of uncertain on how to design this wall that does not have a footing. I need to rely on the leverage of the wall to resist the forces.?????????????

 

[shacked]

How about concrete cassions embeded into bedrock spaced per the soils report with the wall spanning in between? Then the cassions would be designed at a cantilever column with a point load located x ft above the point of fixity.

Just curios Stru, but are you an engineer? Doesn't sound like you are, but that is just my opinion.

 

[msquared48]

What you are talking about, as I posted in your other thread, is a pole footing design, but with concrete.

Mike McCann
MMC Engineering

 

[DaveAtkins]

I agree with Mike--design a one foot width of wall as a pole. There are formulas available for designing an embedded pole with lateral force and moment at the surface.

DaveAtkins

 

[StruKturdg]

I guess I would use L-Pile?

 

[DWHA]

Have you considered stay in place sheetpile? If looks are a concern, you could shoot studs on after installation and apply form lined concrete. Does not look too bad.

 

[StruKturdg]

The problem that I have, and I didn't state, is that there is about 8' between buildings and about 16" from the face of the existing retaining wall and an existing building. The existing retaining wall has cracked and failed, and we need to put a new retaining wall to protect these million dollar homes. See attached

 

[StruKturdg]

Here is another picture

 

[Lutfi]

Yeah, Why not use sheet piles? You can encase them with concrete if need be just as DWHA stated. Assuming that you can find a section that can have adequate section modulus and the existing retaining wall footing is can be removed.

Regards,
Lutfi

 

[StruKturdg]

Don't you have to have room to drive the sheet piles?

 

[msucog]

extend the wall far enough in to the ground to resist the overturning...(this may be what a few of you are suggesting). or maybe include a psuedo-buttress. you could also look at some sort of micro pile, helical anchor, etc.

 

[DRC1]

Do not excavate for a new wall. Get a geotech involed right away. Some questions that need to be answered - 1. Why is the wall failing? Could be inadequate toe, could be subsurface problem( soil piping into a drain etc.) how is the upper building supported and what is the effect on the wall? What utilities are in the area? If you try to excvatae for a new wall, you are likely to lose the existing. It does not appear you have sufficent width to drive sheeets, nor do you have sufficent access, nor are you suffiecently clear of the buildings to prevent vibration damage from driving. We can not give you a good answer from the photgraphs except to say you REALLY need a geotech. My best guess youd be that you would need to either pit underpi the foundation of the higher house after bracing the wall to the lower house and then building a new wall. If the footing for the upper house is higher than the excavation of the lower house, This will get expensive.

 

[dgkhan]

I second DRC1. and if he is right than probably pressure grouting or compaction grouting are the costly options available to stabilize the foundation soil strata.