Predicting Pipeline Failures Through Soil Resistance

Buried pipelines, especially those for water distribution, are susceptible to damage during hazardous events like earthquakes and landslides. Too often this damage harms communities by leading to a disruption of critical services such as water. The frequency of pipeline failures shows how vulnerable our pipelines are and how important it is to increase our understanding of these systems by mechanistically evaluating soil-pipeline interactions and related failure modes — and where existing methodologies may be insufficient. 

As Exponent's Hailey-Rae Rose, Ph.D., and co-authors explain in their study, "Axial Resistance of Pipelines with Enlarged Joints," current methods for predicting the axial force along a pipe underpredict the force demands and oversimplify the mechanics of soil resistance on the joint face. This is because current design standards for predicting axial force on a pipeline only consider frictional resistance along the pipe barrel, i.e., a straight pipe segment, not at the joint, where even a small increase in joint size can increase the frictional resistance by six times compared with the pipe barrel alone. 

In their publication, which was awarded the Article Editor's Choice in the September 2024 edition of the Journal of Geotechnical and Geoenvironmental Engineering, Dr. Rose and co-authors developed a model to predict axial forces by understanding how soil resistance is developed at a joint face due to various soil and pipe characteristics. 

First, they quantified the soil-pipe restraint interaction by developing a predictive analytical model that considers soil resistance and joint size in determining axial forces along a pipeline. They verified their prediction equation through 12 centrifuge experiments — representing buried water pipelines — that were conducted to explore the impact of burial depth and pipe joint diameter. They concluded that the proposed prediction equation will "have future applications to other buried structures because it is based on mechanisms of passive resistance commonly encountered in underground structures and lifelines."

From the publication: "The presented analytical solution provides a mechanistic approach to understanding how soil resistance is developed at a joint face due to various soil and pipe characteristics."