Hello.

If the underground piping experienced live loads, can we use LC Peng's approach? How could this "live loads" be treated?

Thanks

Since underground piping is considered constantly supported, it is customary in Caesar II to ignore these live loads. Perhaps the loads would effectively change the soil stiffness, but I don't know of a method to calculate this. You cannot input these loads as uniform loads because buried pipe is analyzed without weight so G-forces would have no effect. Normally, buried pipe is analyzed only for secondary loads such as thermal expansion and sustained and occasional loads are not fully considered (longitudinal pressure stress is still calculated). If anyone has an accurate method for analyzing a buried system subjected to live loads in Caesar II I would love to hear about it.

Whilst doing underground HDPE years ago, the Driscopipe catalog and guidelines provide methods for good design say for under road crossings etc. but the methods may not apply directly to steel pipe.

Check with your Civil guys for some help. Remember this is a LOCAL effect trying to crush the pipe, CII will not be much help.