Read about START-PROF pipe stress analysis software
The pipeline laid on the ground or seabed is not buried. It is continuously supported.
Let's assume, that pipeline is completely exposed, only friction forces acting in the horizontal directions. This pipeline can be modeled using multiple resting supports placed with approximately 5D spacing.
The friction factor can vary from 0.4 to 1.0, depending on the soil type and pipeline casing material:
j - soil internal friction factor
nm - soil-pipe adhesion factor, depending on insulation casing (jacket) material. Recommended values for bare steel pipe nm=1, for PE casing nm=0.7