How to calculate average vertical stress in underground coal pillars using fish functions

Hello everyone
Can somebody tell me how to use the fish function to calculate the average vertical stress on underground coal pillars?

@Prashanth, I am not a specialist in it, but it seems to me that the idea would be to iterate through the zones belonging to the pillars (or some parts of them), get vertical stress in each zone, and then average the stress for each pillar. Is this something you’re trying to do? If so, the only question is how to identify zones within pillars. If you have pillars group(s), you can simply check the group of each zone while iterating through all zones. If not, I would suggest checking their location (e.g., vertical position).

There is an example problem in FLAC3D manuals where pillar load is calculated. You can use it to calculate average load on pillar.