Retaining Wall 2 ft from Rock
Retaining Wall 2 ft from Rock
(OP)
I need to design a retaining wall 2 ft away from a vertical rock surface. Do I use the full 40 PSF equivalent fluid pressure (for granular fill and good drainage) or I can use a reduced load. I know theoretically fluid pressure is only related to height and not related to width or volume. But in reality if my wall is only 1 in. away from rock, the load should be very small.
Also, I need to dowel the footing into the rock to resist sliding force. Use #8 with non-shrinkage grout, what kind of design guide shuold I use. Contractor wanted to drill vertically in to rock underneath the footing, is that acceptable? The rebar is able to take the shear but the force concentration at the rock/concrete might crack them.
Thanks
Also, I need to dowel the footing into the rock to resist sliding force. Use #8 with non-shrinkage grout, what kind of design guide shuold I use. Contractor wanted to drill vertically in to rock underneath the footing, is that acceptable? The rebar is able to take the shear but the force concentration at the rock/concrete might crack them.
Thanks





RE: Retaining Wall 2 ft from Rock
What's the application? How competent is the rock?
Jeff
RE: Retaining Wall 2 ft from Rock
RE: Retaining Wall 2 ft from Rock
Could you give a more complete desciption of the situation? Why are you proposing a retaining wall if the rock face is stable?
I would think that a shotcrete facing with some sort of reinforcement into the rock face would be more appropriate, unless you have something that needs to bear on the top of the wall.
Please expand on the situation.
Jeff
RE: Retaining Wall 2 ft from Rock
The site soil condition varies a lot, in some area there are just silty clay. So we need a long wall with different design considerations. Thanks
RE: Retaining Wall 2 ft from Rock
"Earth Pressure on Retaining Walls Near Rock Faces"
Sam Frydman and Israel Keissar, Journal of Geotechnical Engineering, ASCE, June 1987, Vol 113, No. 6
The pressure is less than the active earth pressure because the full active soil wedge cannot develop.
RE: Retaining Wall 2 ft from Rock
RE: Retaining Wall 2 ft from Rock
Perhaps you should get a local geotech in your area to help you. Variable conditions warrant a professional opinion with local knowledge and experience.
Jeff
RE: Retaining Wall 2 ft from Rock
RE: Retaining Wall 2 ft from Rock
Perforated pipe and weep holes will be used to ensure good drainage, I think water will not be a issue. Please correct me if I'm wrong. thanks
Sean
RE: Retaining Wall 2 ft from Rock
Logically, simplistically considering a 45 degree slope failure/slip plane, if there is not the volume of soil to be retained, the lateral earth pressure should be able to be reduced, but that call is up to your geotech.
Mike McCann
McCann Engineering