Trust but Verify: For Users and Specifiers
Not all pipe types are the same; neither are their design assumptions. Flexible pipe requires a strong side-fill to develop strength as it shortens vertically, deflecting outward to engage the side fill as a column to carry some of the vertical load; and as a bearing to resist horizontal deflection. Rigid pipe relies very little on the horizontal support given by the side-fill soils, and provides the strength within the pipe wall composition. Based on this difference, installation assumptions should not be the same.
