Retaining wall design - one behind the other
Retaining wall design - one behind the other
(OP)
I am designing a stepped retaining wall system where the upper wall is within the zone of influence of the lower wall. Many available design programs allow for the vertical load to be included in the analysis (location, width, load, excentricity, etc). Non, that I can find, allow for the lateral load developed by the friction between the soil and the footer of the upper wall to be applied to the lower wall in any rational manner - except in some rule of thumb manner. Does anyone have an idea of a program that will do this or an idea of how to apply the Boussinesq equation to a analysis of both a lateral and vertical load. Also, any suggestions of reasonable rules of thumb would also be appreciated.
Thanks much - the hair is getting greyer.
Thanks much - the hair is getting greyer.






RE: Retaining wall design - one behind the other
RE: Retaining wall design - one behind the other
Apply the horizontal reaction as a line load to the lower wall at the same height to get the additional overturning. At half the height of the footing.
RE: Retaining wall design - one behind the other
Or apply the foundation load as a strip load/uniform surcharge above the lower wall. Don't forget to check both walls (upper, upper+lower) for global stablility!
FHWA has specific design guidance for superimposed MSE walls.
Jeff
RE: Retaining wall design - one behind the other
The only thing I would do different, is apply the horizontal forces at their locations:
Passive pressure: 1/3 up from B.O. Ftg.
Friction force: @ B.O. Ftg.
You need to use a live load (1.6) factor not the actual forces for the horizontal forces on the lower wall as the F.S. against sliding for the upper wall is still 1.5.
FYI, depending on how close the upper wall is in relation to the lower wall, the reinforcing and footing geometry for the lower wall should be pretty close to what it would be if it were full height.
RE: Retaining wall design - one behind the other
RE: Retaining wall design - one behind the other
RE: Retaining wall design - one behind the other
RE: Retaining wall design - one behind the other
Thanks for the input. I can probably find the book in a not so local college engineering library (I guess we are both old and grey since I have at least one of Peck's texts, but not that one).
Thanks