Passive Pressure on Anchored Wall w/ sloped bank
Passive Pressure on Anchored Wall w/ sloped bank
(OP)
I am designing a timber bulkhead. The grade in front of the toe of the bulkhead is sloping away and down at 4:1. I am trying to determine the appropriate embedment length. Can I still account for passive pressure gamma*kp since it is sloping down & away? I was thinking that instead I should be checking shear failure of the the soil wedge along the plane perpindicular to the bottom of the face pile (soil weight*tan phi?). Is there some way to determine minimum flat distance in front of the wall before it slopes to consider the passive pressure?
Also IBC has values for lateral active pressure, lateral bearing capacity, friction coefficent. Do these apply to retaining wall design or only foundation? If they apply I assume the friction value is for concrete against soil not soil shear (i.e. tan phi as mentioned above)? And regarding the lateral active pressure and lateral bearing capacity: what if you have a portion which is below the water table you would have to back calculate the ka & kp used based on an assumed soil weight and then recompute? this seems convoluted, would it be against code (ibc) to base your ka, kp off of an assumed phi & used assumed moist and dry soil weights?
Any help would be greatly appreciated, thanks
Also IBC has values for lateral active pressure, lateral bearing capacity, friction coefficent. Do these apply to retaining wall design or only foundation? If they apply I assume the friction value is for concrete against soil not soil shear (i.e. tan phi as mentioned above)? And regarding the lateral active pressure and lateral bearing capacity: what if you have a portion which is below the water table you would have to back calculate the ka & kp used based on an assumed soil weight and then recompute? this seems convoluted, would it be against code (ibc) to base your ka, kp off of an assumed phi & used assumed moist and dry soil weights?
Any help would be greatly appreciated, thanks





RE: Passive Pressure on Anchored Wall w/ sloped bank
RE: Passive Pressure on Anchored Wall w/ sloped bank
But how about my question about if and how to use those values in IBC table 1804.2, specifically the lateral bearing values...do you think they apply to passive pressure of earth retaining structures? my design seems unreasonably conversavtive using these values instead of basing on Kp and assumed soil weights??
RE: Passive Pressure on Anchored Wall w/ sloped bank
Can you describe your timber bulkead a little bit more. long term Deflection and preservative treatment are issues.
RE: Passive Pressure on Anchored Wall w/ sloped bank
Unfortunately it doesn't warrant a geotech. I was planning to calculate passive/active coeffiecients using the rankine method based on an assumed phi corresponding to the soil type, and using assumed moist and dry soil weights for pressure computations, what do you think?
Its a relatively small wall. 5' exposed face, with water level about half way, with tie rods to concrete deadman anchors. The slope running away from the wall is 4:1, SP-SM soils, & no significant surchage loading expected. I was using the following guide from the sp council as a starting point and backing it up with my numbers ht
I have another wall that has an 8' exposed face but this one is embedded in relatively level river muck. Any advice on passive pressures of muck?? I was thinking don't worry about the passive at all and provide two anchors one at top and one at the bottom to stabilize, any thoughts? I know in practice they don't go this overboard but I think alot of what is built cannot be backed up by calculations...