Uplift pressures on dams 2

[pelelo]

I am trying to analyze the uplift pressures on a dam and compare them with the overburden pressure or applied pressure in order verify how safe would it be.

I am using a finite element software for computing the uplift pressures.

As an example my max uplift pressure value is around 60 kPa (60 kN / m2), which occurs somewhere in the mid section of the dam. I understand it is 60 kN / (1 mt perpendicular to the analysis x 1 m along the section).

In this case, applied pressure on that specific point would be the concrete unit weight (it is a concrete dam) x (1 mt perpendicular to the analysis x 1 m along the section). This confusion arised as by overburden or applied pressure any person would understand gammma x height, but this last concept is not applied as it was for the max uplift pressure computed by the software.

Is this a correct assumption?, please let me know. I haven't see any clear example about this.

Another thing, is there minimum required FS agains uplift in dams?, I have few books but none specify any minimum FS required.

Thanks

 

[cvg]

draw your free body diagram. you will have lateral load of the water / waves, dead load and uplift at the foundation. If the dam overtops, than add hydrostatic pressure downward on the dam as well. assuming concrete dam, the dam will fail in overturning or sliding or in structural failure of the concrete. your resisting forces are compression / shear at the foundation at the toe of the dam, friction against the foundation and friction or embedment at the abutments. Don't forget about seismic.

first, determine if your dam is a jurisdictional structure, if it is than you must get a permit from the regulatory agency and they will set the FS. they will also gladly help with non-jurisdictional dams. If you are in the US, than visit this site:

http://asdso.org/

or

http://ussdams.org/

if all that fails, the US Army Corps of Engineers has published guidelines that are widely accepted

http://140.194.76.129/publications/eng-manuals/EM_1110-2-2100_sec/EM_1110-2-2100.pdf

 

[molerat2210]

There is an army corp of engineers manual for gravity dam design. All the formulas, etc. are in there to calculate uplift. Finite element software not needed.