Sheet Pile Design and PROSHEET software 1

[mleepennon1]

I just read through thread "486-177557," but I didn't see an answer to the question I have regarding the sheet pile design software PROSHEET.

The Total Pressure Diagram in the results tab of the program does not look like the pressure diagram I was expecting.

The is no passive pressure "behind" the wall like this diagram shows:

The pressure diagram in PROSHEET simply follows the dashed line in the image (from point G to the bottom of the pile).

Because of this, when I compare a simplified problem in PROSHEET to a spreadsheet I put together, the results are not the same.

I do not believe I can trust PROSHEET if I have a more complicated situation that includes a surcharge pressure, variable soils, etc.

Does anyone know if the pressure diagrams, the design depth, and the moment calculations in PROSHEET work?
Or do you know why PROSHEET's pressure diagram does not look like this image?

 

[PEinc]

The sheeting pressures you show in your figure above follow Teng's "conventional method" for design of cantilevered sheeting design. This is an iterative process that is not usually or easily employed by computer programs. I believe that this method is unnecessarily complicated. CivilTedch, and I believe ProSheet, use a simplified method where you put the active pressure on the back side of the wall and the passive pressure on the front side. Then, you solve for the embedment depth that provides moment equilibrium. Then, you increase the calculated embedment by 20% to 40% (20% is most common). This is described in Teng's 1962 Foundation Design on page 358-362 as the "simplified method." It makes no sense to me to increase embedment in an effort to achieve force equilibrium in the x-direction. If you have moment equilibrium, the required passive resistance will always be greater than the active driving force due to difference in moment arms.
Both the conventional and simplified methods work. However, they will give slight differences in the required sheet pile section modulus and length.
Search other past threads for more detailed discussion on ProSheet.

http://www.PeirceEngineering.com

 

[PEinc]

Also, the reason there is no passive pressure behind the wall in your figure is because you are plotting the net pressure (Pa - Pp) instead of plotting Pa and Pa individually. Netting out the pressures just adds more number crunching steps when you solve for moment equilibrium.

http://www.PeirceEngineering.com