×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Upside Down Retaining Wall

Upside Down Retaining Wall

Upside Down Retaining Wall

(OP)
Hello folks,

I've been dealing with a challenge that I could definitely use some help on.

My client is looking to build a home on a relatively steep slope, going downhill from the face of the structure. The garage, which is at the face, is at the highest point at grade, and the grade continues to dip such that the worst case scenario is that the back of the wall of the garage is 12'-6" above grade.

I was thinking that an upside-down retaining wall, where the stem walls would serve in retaining the soil from below the garage, and the toe, which would serve as a mat slab, would be an alternative. Would this work? Any special considerations I should make note of?

Does anyone have any better ideas? A conventional retaining wall is not an option because of the proposed structures proximity to the neighbor.

Thank you,
R

RE: Upside Down Retaining Wall

I would have to see a sketch to understand what you are trying to accomplish. Would also be helpful in understanding the site constraints.

On the surface, it sounds like someone is trying to jam too big a structure onto to small of a lot.

Mike Lambert

RE: Upside Down Retaining Wall

Not totally sure what you mean but we have used drilled piers with a retaining wall spanning horizontally between them at the toe of a slope to retain the soils.
If your retaining wall is tied back into the house, analyze the block of soil beneath and make sure the whole thing won't move. You may find yourself saying to your neighbor, "Mi casa es su casa".

RE: Upside Down Retaining Wall

(OP)
Forgive the poor drawing, but this is an 'artistic' section of what I'm proposing.


Any thoughts?

RE: Upside Down Retaining Wall

Where's the grade outside the retaining walls? How will you construct this? Do you have a soils engineer to help you?

RE: Upside Down Retaining Wall

(OP)
The grade outside the retaining wall would be at the bottom of the stems. I would probably design temporary shoring confining the soil within, and pouring or shotcreting the face of the concrete walls. No input from the soils engineer yet.

RE: Upside Down Retaining Wall

You would need probably three levels intermediate concrete encased tie beams, the first at the bottom, intermediate and top, depending on the height of earth retained, all to keep the walls from spreading without external shoring. This can be done, but you are looking at hand tamping the fill. the two walls 90 degrees to this would be interesting...

Mike McCann, PE, SE (WA)


RE: Upside Down Retaining Wall

Wouldn't it be easier to just put a structural floor in for the garage?

Mike Lambert

RE: Upside Down Retaining Wall

GeoPaveTraffic's solution would be mine. You can use the void under the garage for storage, and you don't have to bring in all that fill material.

RE: Upside Down Retaining Wall

Maybe construct it like a marine pier: set sheet pile (or equiv.) walls with tie backs between them, backfill and add more levels of tie rods. You could backfill with soil cement or lean concrete to keep lateral loads low. Angle the tie rods at the corners like at cofferdams.
Marine dolphins are built like this all the time.

RE: Upside Down Retaining Wall

(OP)
@Geo and Hokie - I suggested the very same thing as well. The issue is that the planning department in this particular area is militant about uninhabitable space being converted illegally into habitable space, from what I've been told.

@Buggar - I think I'm understanding what you're saying, but do you have any samples I can look at?

RE: Upside Down Retaining Wall

A lot of the piers in San Diego are constructed using sheet pile walls with cross ties. The Edmonds Ferry Terminal up in Washington, too. The sheets are driven to depth to restrain the toe but your design would allow low level cross ties to hold the toes.
I've also seen MSE walls (mechanically stabilized earth?) similar to what you are doing and refer you to the manufacturers of these systems.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources