Mudslide Effects on Offshore Pipelines

In regions of unstable soils such as portions of the Mississippi Delta, occasional pipeline failures during periods of severe weather have been attributed to mudslides. The effects of such downslope soil movements on the deflection and resulting stress in a pipeline have been studied in an attempt to reveal methods of routing or design which would reduce the risk of failure. Results show that the chances of surviving a slide are increased if the pipeline outer diameter is reduced to as small a value as possible, if the pipe wall thickness is increased, and if some slack is available in the line. The chance of survival is greatest if the slide occurs in a direction perpendicular to the pipeline route since the failure mode is primarily one of tension. When the slide crosses the pipeline at other angles of incidence, the chance of survival is significantly lessened.