Could you please let me know how it could be simulated in Caesar for an under ground piping?

I assume you are worried about lateral pipe movement rather than axial properties. First you need to specify a specific grade of Ethafoam (like 220), and get the Compressive strength from the vendor at your compression. We use 25% compression, eg for 1" of pipe movement you would provide 4" thickness of ethafoam.

You can then calculate properties of a soil model to match the strength of the Ethafoam. You should find the ethafoam to be much weaker than the normal soil, which of course is the point in using it.

Thank you,

good!