Assumptions for water table height for a retaining wall design.?
Assumptions for water table height for a retaining wall design.?
(OP)
I have a project given to me to design a retaining wall. It will be back filled with gravel with weep holes to act as drainage. However the problem is how high should I assume the water table to be. If I design it for a full water table, this gives me a very over engineered design. But it Is safer. If assume that the weep holes will take care of the water and put 0m, This could disregard possibility's in the future.
What is a safe assumption used in the industry, half?
Soil conditions are thick clay.
Im seeing people do different things, some say 0m, some say full, some say 60%. please help
What is a safe assumption used in the industry, half?
Soil conditions are thick clay.
Im seeing people do different things, some say 0m, some say full, some say 60%. please help





RE: Assumptions for water table height for a retaining wall design.?
Now inboard of the weeps, there will be some phreatic surface. At some distance removed from the actual wall, do you have some sense of the water table? It may just require some guess work (or a confocal parabola) to forecast the water table inboard of the wall.
So, what data do you have to generate the boundary conditions?
f-d
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RE: Assumptions for water table height for a retaining wall design.?
RE: Assumptions for water table height for a retaining wall design.?
RE: Assumptions for water table height for a retaining wall design.?
Dik
RE: Assumptions for water table height for a retaining wall design.?
RE: Assumptions for water table height for a retaining wall design.?
IMHO, 1.8 meters.
Assume, for a moment, that you assume 1.0 meters. The difference in that (uninformed) assumption and full wall height is 0.8 meters... an extra 0.8 meters head is not much additional hydrostatic pressure. Don't try to "fine tune" a retaining wall design, there are too many other factors... say, maybe an unexpected surcharge in the future.
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RE: Assumptions for water table height for a retaining wall design.?
Mike McCann, PE, SE (WA)
RE: Assumptions for water table height for a retaining wall design.?
RE: Assumptions for water table height for a retaining wall design.?
I an involved in a project where the retaining wall is moving. In reviewing the initial design calculations, it's apparent that the geotechnical design did not consider water table at the spring line of the weeps. They just figured, there are weeps, so there is no water pressure.
When I develop the free-body diagram, consider Ka, Ka and tan(delta) and show no water pressure, there is no problem. When I consider water pressure acting below the weeps, there is a design problem.
The wall has slid over 14 inches.
The pavement above the wall has cracked.
(Yes, this is a small wall, but in answer to the question, the design, "Should" consider water pressure acting below the weeps, which are rarely at the exact foundation bearing level.)
f-d
ípapß gordo ainÆt no madre flaca!