Effectivness of retaining wall key?
Effectivness of retaining wall key?
(OP)
When checking sliding for a cantilever retaining wall with a footing key,
1) Is it correct to include active pressure behind the wall down to the bottom of the key or only down to the base of the footing.
2) Does this depend on if the key is at the front, middle, or back of the footing?
In "Foundation Design and Analysis" by Bowels, it states that the recommended location of a key is at the back (retained soil side) of the footing. Then it says, "The increase in "H" by the depth of the key may null its effect.
I am not sure if the increase in "H" is necessary for key locations other than at the back of the footing.
1) Is it correct to include active pressure behind the wall down to the bottom of the key or only down to the base of the footing.
2) Does this depend on if the key is at the front, middle, or back of the footing?
In "Foundation Design and Analysis" by Bowels, it states that the recommended location of a key is at the back (retained soil side) of the footing. Then it says, "The increase in "H" by the depth of the key may null its effect.
I am not sure if the increase in "H" is necessary for key locations other than at the back of the footing.





RE: Effectivness of retaining wall key?
f-d
¡papá gordo ain’t no madre flaca!
RE: Effectivness of retaining wall key?
Keys are not a very effective way of increasing the sliding resistence. That was the point Bowles' was trying to make.
RE: Effectivness of retaining wall key?
RE: Effectivness of retaining wall key?
I'm also not sure of GeoTrafficPave's contention that it wouldn't matter where the shear key is located. To me there is some fundamental difference, whether it amounts to an effect on the design would require that I work up the problem. That said, there may be some theoretical difference (at the risk of repeating myself) on the calculated passive resistance.
f-d
¡papá gordo ain’t no madre flaca!
RE: Effectivness of retaining wall key?
You design the wall with a conventional spread footing (i.e. active pressures to the underside of the base) and if you have a sliding problem you add a shear key. The wall doesn't expereince any additional disturbing forces due to the addition of the key, so why change the analysis.
RE: Effectivness of retaining wall key?