Surface Impact Loads for Buried pipeline

1. Maximum impact load
           The impact loads described in this section are those resulting from large weights falling from significant heights. In this case, the use of an impact factor F , as applied in Section 4, is not sufficient to estimate the effect of the impact load on the buried pipe. The surface impact load due to the weight W of a fallen object   
2.Penetration and PPV
            For impact near the pipe location, the increased pressure transmitted to the pipe can be evaluated as described in Section 4 where Pmax is the applied surface load. This evaluation considers the ovality, through-wall bending, side wall crushing, and ring buckling. In addition, the burial depth should be sufficient to guard against ground penetration by falling objects.
Example problem see the link
http://www.4shared.com/document/pfUVB8pb/Example_problem_for_Maximum_Im.html