How to account for the weight of soil acting down on the pipe in AutoPIPE?
First the weight of soil is taken into consideration in the calculation of Soil Restraint Properties against upward and downward movement for each Soil ID modeled. Design approximations for this type of movement are based on studies of earth anchors subjected to vertical forces. The resistance consists of two parts: the weight of the soil wedge (Ws) above the anchor; and the shear resistance of the soil wedge being moved.
Further analysis with weight of soil weight above a pipe can be performed with "Buried Pipe Result Model Options" command. This command can be used to specify options when calculating the Code combinations for Soil overburden loads like Ring Buckling stress and Circumferential Wall Bending stress. Also, sustain code combination would be affected by enabling soil overburden option "Add Circ. bending stress to Sustained".
Therefore, if one feels that soil weight has not been addressed with aforementioned options, than one suggestion would be model weight of soil above a pipe as a distributed load.
Model Soil Properties with Soil Calculator and Underground Piping