Passive Resistance in front of Cantilever Ret Wall
Passive Resistance in front of Cantilever Ret Wall
(OP)
Referring to the usual references (Bowles, Coduto, Das), it is customary to neglect the passive pressure developed on the front face (toe side) of the cantilever wall's footing. The explanation given is that " The bottom of the footing may move slightly rearward if any overturning failure were to occur. Therefore, the resistance offered by the passive resistance acting on the front of the footing is not reliable, and should be neglected in the overturning analysis."
The condition that I have is as follow:
-> retained height is 10 feet on the heel side
-> soil height over the toe height is 4 ft. this is 4 ft above the footing, against the front of the WALL (not just the footing).
I am using the weight of the soil (vertical component) over the toe as a resisting moment. However, considering the height "D" of this soil, the potential additional resisting moment is Kp * gamma * (D^2) * (1/2) * (D/3). I believe that since the height of the soil is quite high (i.e., extends against the wall, not just the footing), it would be quite U-N-C-O-N-S-E-R-V-A-T-I-V-E not to include it in the overturning analysis.
Any feedback on this approach is appreciated...
By the way, I am working with tight spatial constraints so the size of the footing is critical and thus the above dilemma...
Thanks!
The condition that I have is as follow:
-> retained height is 10 feet on the heel side
-> soil height over the toe height is 4 ft. this is 4 ft above the footing, against the front of the WALL (not just the footing).
I am using the weight of the soil (vertical component) over the toe as a resisting moment. However, considering the height "D" of this soil, the potential additional resisting moment is Kp * gamma * (D^2) * (1/2) * (D/3). I believe that since the height of the soil is quite high (i.e., extends against the wall, not just the footing), it would be quite U-N-C-O-N-S-E-R-V-A-T-I-V-E not to include it in the overturning analysis.
Any feedback on this approach is appreciated...
By the way, I am working with tight spatial constraints so the size of the footing is critical and thus the above dilemma...
Thanks!





RE: Passive Resistance in front of Cantilever Ret Wall
RE: Passive Resistance in front of Cantilever Ret Wall
RE: Passive Resistance in front of Cantilever Ret Wall
RE: Passive Resistance in front of Cantilever Ret Wall
RE: Passive Resistance in front of Cantilever Ret Wall
true, but at the same time, isn't the procedure for cantilvered walls utilizing active pressure on the heel side of the wall? If active pressure develops (and the associated movement with it), then the other (toe) side of the wall is experiencing a reaction in the form of passive pressure...
RE: Passive Resistance in front of Cantilever Ret Wall
The use of passive pressure is more easily justified for deep pile, and deadman in anchorage system, which usually possess the essentials (intensity of load & large/deep soil mass) to allow passive state to occur.
RE: Passive Resistance in front of Cantilever Ret Wall
As a further thought, if the wall is not tied into some unyielding object, why not let it heave? Then it will behave like the soil it is supporting.
BA
RE: Passive Resistance in front of Cantilever Ret Wall
RE: Passive Resistance in front of Cantilever Ret Wall
f-d
¡papá gordo ain't no madre flaca!
RE: Passive Resistance in front of Cantilever Ret Wall
And, as others have pointed out, it takes substantially greater soil strains to mobilize full passive as compared to full active lateral soil stress conditions. That's a primary reason why passive resistance is either ignored, or greatly reduced with a factor of safety.