Hi Experts,
I had a question on underground pipe modeling,
My pipeline go vertical down 2 meter and then go horizontal 50 meters, and turn horizontal 90 degree go anther 25 meters.
I marked node number as
10- 20 (horizontal; above ground)
20-30 (vertical down; 30 enter soil)
30-40 (vertical)
40-50 (horizontal; underground x direction)
50-60 (horizontal; underground -z direction)
60-70 (vertical up; 70 leave soil)
70-80 (vertical)
80-90 (horizontal; above ground)
my question:
do I need to break node 30-40 into several elements (for example 5 or 10 meter/element), and renumber them? or let CII to do it?
Thanks
Li

I'd suggest letting CAESAR II do the re-meshing. This way the computed restraint stiffnesses will be appropriate for each element.

Vertical runs are a bit of a question in our buried pipe modeler - axial, vertical up and vertical down definitions are confused. Take a closer look at the model created.

There is no reason to renumber other than to maintain the increasing sequence in the program-generated nodes. I might suggest starting with node 100 and incrementing by 100 in the initial, "unburied", model.

I have an add-on to this question regarding burying vertical piping. On a model where the pipe goes straight into the ground as it does in the above model, how would you set your buried model to handle this. What I have done for angled piping is set an average buried depth over the span from surface to where the pipe levels underground. For the straight vertical piping, will CAESAR auto adjust the restraints over the length of buried pipe, or should I put a small depth over the vertical section, i.e. For a pipe that is buried 3ft below grade, on the vertical section, would a depth of 6 inches be a good conservative approach to allow for some movement due to loose topsoil?

Could anyone shed light on this question?

The CAESAR II buried pipe modeler is focused on horizontal pipe. Generally, the vertical runs are not significant in system response.
Perhaps a different soil model could be defined for a vertical run. If it's a long vertical, you could even consider different soil models along the vertical, each with its own "depth to top of pipe". But I would guess an average depth be used as opposed to your 6 inch approach for a 3 foot burial.
I would try a few different parameters to see if it has any influence of the results.

I usually create a soil model for the average depth when the pipe exits or enters the ground at an angle, but for a straight vertical pipe I assume the 6" because the soil at the surface will not be as compacted and so offer little resistance. But what you are saying seems to imply that for short vertical runs, they are not necessarily impacting on the system? I'm my work, the deepest I have modeled vertical runs is just under 6 feet. Do you typically ignore burying vertical pipe of shorts runs such as this?

I will try to run a few different models in the mean time to see what the results do from one to the other.

Another issue with vertical buried pipe is that the local orientation of the pipe screws up the typical "up", "down", and "transverse-horizontal" orientation.
To me, short vertical runs would simply segregate the attached horizontal which would have their own "buried depth to top of pipe". I would not expect much impact on the resulting pipe position. I guess the one exception is with entry and exit points - maybe using half the bottom end's "buried depth" would be sensible choice.
I agree with your approach of running a few "what if?" models. This sort of sensitivity study will show how your input changes affect the specific piping layout.