for underground pipe live load, you can use
1, ALA
2, AISI AWWA M11,
3, PPI (Handbook of Polyethylene pipe of the plastic pipe institute)
4, CEPA equation (Warman Hart and Francini, 2009)
5, CSA S6-10 CHDB (Canadian Highway Bridge Design Code)
6, API RP1102
7, American Association of State Highway and transportation officials design Guide,
each method has their own focus,