I am concerned about whether to use Epoxy CS and GRP as per for 68" Seawater line.
And Civil also is worried that if we use GRP, due to water in the UG, the UG GRP piping might be floated in the water.
So, I would like to ask the check of Buoyancy effect by CAESAR II for in cases of Epoxy CS and GRP respectively.

can anyone guide how to apply or check buoyancy effect in cII

First, I would advise that even metal piping can be susceptible to buoyancy effects if gas is inside of it. Near swamps, piping is known to "float" out of the earth if the earth is significantly wet.

Buoyancy effects are able to be effected in the Wind/Wave tab by enabling "wave."

Hit F1 while in CAESAR to pull up the help files if you need quicker help.

thanks dear ,

should I check it float in sustain case, and what will be the load case for this . the sea water line is in trench . and depth of top 1.5 mtr . in wave option we need to input marine growth and its density . can anybody explain the line in trench buried than what should I need to input for these value.

but I think wave will come only when line near shore or on jetty trestle , the trench depth is approx. 2.5 mtr .

please guide me how to check pipe lift / float due to buoyancy.

thanks & regards
Ava_shrivas

By specifying "Wind," you have to input parameters for wind in the load case editor, which will operate based on the shape factor you specify in the wind/wave tab.

Likewise, by specifying "Wave," you have to input parameters of the wave in the load case editor, as well, which will operate based on the details you specify in the wind/wave tab.

The wave feature solves several water-related issues at the same time, though you may decide many may be inapplicable to your analysis. Simply enabling the wave instructs CAESAR that the pipe is submerged in water and buoyancy effects are applied.

If you're not considering wave actions in the horizontal, it won't really matter what Drag Coef Cd is.

If you're not considering movement of a floating facility dragging the pipe up and down in the water, then Lift Coef won't matter.

If the above two statements are true, then you likely won't need to consider inertial effects for Added Mass Coef Ca.

Marine growth and density work the same way as insulation. It makes your pipe heavier, bigger, though more or less dense based on your input. If you don't want to consider marine growth, specify 0.

In the load case editor, go to the Wave Loads tab and if you're not considering wave loads, just specify the variables to be 0, but input the appropriate data under "Sea Water Data." Set up your load cases to include WAV1.

With regards to sustained loads, you have to ask yourself the following:
•Will the pipe exist in an installed position outside the water? I.E. will it be constructed and sit for a few days before it gets placed in the water?
•Will the pipe operate in the water and out of the water?

You should also ask yourself:
•If the pipe is built on land, how will it be submerged into the water? Quickly? Do I need to consider drag loads while it's being put in place?

As a side note, if you don't want to deal with the wave load editor, calculate buoyancy force on the pipe per unit length and apply them under the uniform loads tab. You could also do any aforementioned drag forces in a similar manner.

I do not know if CAESAR II is set to evaluate your situation. We have buried pipe and we have buoyancy calculations but we do not have buoyancy calculations for buried pipe.
Our ALA soil modeler considers pipe laid in below the water line -
you specify a soil density and also an effective soil density. The effective soil density reflects the pipe/soil interaction where water is involved. But this soil model does not lift the pipe in the buried model.
The wave load processor in CAESAR II has a buoyancy component, this will provide lift in the pipe but this is applied to a pipe under water, not in soil.

After rereading a second time, some of my words above are only applicable if the earth is very wet and is wet all of the time. If, instead, it's a time transient situation, then the reality would be as follows:

1. You bury the pipe and for all intents and purposes, it acts like normal underground piping.
2. At some other time, water seeps in and permits buoyancy effects that are offset by the mixture's viscosity, which is very significant. At this time, the soil-spring model is compromised due to change of ground composition.
3. The ground may or may not dry out again, leaving your pipe in a pre-stressed cold-spring state, but otherwise now behaves like underground piping from step 1 (or perhaps not. The soil model may be in a third state).
4. Repeat steps 2 and 3 ad infinitum.

If you assume that given enough time, the pipe will end up in a configuration that's identical to regular water, then you can calculate stresses as though it's in water. Assuming there's nothing to keep the pipe from floating, any sufficiently long length of underground piping is going to fail.

Perhaps the solution is not to try to get CAESAR to accurately depict stresses in the route, but to develop an administrative approach and simplify the problem with concrete sleeves that keep the pipe relatively neutrally buoyant. I would suggest sizing your concrete sleeves for spans equal to normal supports for the pipe so as to maintain consistency, as well as to act as regular supports for the pipe before it's buried.

However, I'll note that without water/earth consistency information, it'll be difficult to target the density you need when designing your sleeves.