Soil bearing loads from UCS

[jtb563]

I have some pipe supports that are holding down 90" fiberglass pipe in a tunnel. The weakest soil I have has a UCS of 250 psi. The flotation caused by grouting one span of pipe is around 18,000 pounds. I need a simple way to show that our 4 - 6" by 6" plates at the ends of the supports will not exceed the bearing strength of the shale and sink into the crown. Each support should have around 6,000 pounds of pressure the way they are positioned on top of the pipe. First time posting on here, but I have read alot of helpful things on this site so I thought I would give it a try.

Thanks!