Propped Retaining Wall Force Distribution 3

Generally speaking I've typically used Peck's trapezoidal distribution for any sort of propped/braced retaining structure.

However I often defer to the project Geotechnical engineer when there is one available.

How are they going to backfill the wall with the slab there?

I would make sure you tell them to brace the wall before they backfill and then remove it after the slab is tied in.

For pressure dist I would ask a geotech.

I'll add that regardless of pressure distribution, for a propped retaining wall your steel is on the wrong face.

WestLevel said:

I would make sure you tell them to brace the wall before they backfill and then remove it after the slab is tied in.

Click to expand...

Does this actually ever happen in practice?

I would design triangular with active pressures to represent the unrestrained construction case, then trapezoidal with at rest pressures for the final restrained case. The wall will need to be reinforced on both faces to account for each case.

It's not propped unless the slab is adequately anchored and reinforced to resist the horizontal force required to prevent lateral movement at the top. In that case, it is just a simple span with rotational restraint at the base.

It's been a while since I've done heavy SOE, but I'm fairly certain you don't get the trapezoid distribution if you have a granular soil behind the wall. Didn't Terghazi/Peck get those pressures during excavation for a subway in cohesive soil?

Please note that is a "v" (as in Violin) not a "y".

In cohesive soils, the bottom of the pressure distribution stays constant instead of reducing back down to zero. In granular soils, the above indicated pressure distribution is correct I believe.

Do you all have a good reference for the Peck distribution, I don't recall ever seeing that before. Would this be applicable to basement walls?

If the wall is to be backfilled before installing the wall restraint, it is a cantilevered wall and, either, you don't need the restraint and it will deflect, or the wall will fall over.
I would not use a trapezoidal earth pressure distribution if the single level of restraint is at or very near the top of the wall.
Most restrained or very stiff walls are designed for triangular, at-rest earth pressure. However, there are references that show how to determine the lateral pressure due to compaction of the backfill.
With your slab restraint being installed above the wall backfill, behind the wall, it seems to me that you need to design the wall as a self-supporting, cantilevered retaining wall which will deflect, causing active earth pressures.
Your rear-face reinforcing steel as shown looks to be more applicable to a cantilevered wall; but, when restrained at the top, you will need steel along the front face.