Active and Passive Soil Resistance on a Buried Pipe.

Unlike piping above ground, pipe supports do not provide restraint for a buried piping system, instead the surrounding soil provides the resistance. This resistance does not act at discrete points like pipe supports but acts all along the length of the buried pipe. When performing an analysis on buried piping, the vertical, axial and lateral soil resistance should be accounted for.

The image below shows how lateral soil resistance changes when a buried pipe is subject to a lateral load. The starting case on the left shows the case with no lateral load applied to the pipe, here the soil resistance in the lateral direction is the same on both sides namely this is the neutral situation.

On the right the case where a lateral load (Q) is applied to the pipe is shown, here it is seen that in front of the pipe a passive resistance builds up as the pipe deflects to resist the load whilst the decreased resistance behind the pipe is called the active resistance. The soil properties determine how much pipe deflection is needed to generate a given passive resistance.

Our self-paced course on "Soil Pipe Interaction" can help you learn more about soil/pipe interaction from the perspective of a piping stress analysis, and our learning path Buried Piping Engineering will explain all the steps in doing a piping stress analysis for a buried piping system.