The Optimum Pipeline Burial Depth Considering Slow Downslope Soil Movement and Seasonal Temperature Variation

Thermal stress induced in a buried pipeline due to temperature variation is of great concern in Canada due to its extreme cold winter and warm summer. Thermal stress decreases by increasing the pipe’s burial depth while the interaction forces due to ground displacement increase by increasing the burial depth. As a result, the optimum burial depth of a pipeline is of great importance to pipeline companies to minimize interactions between the pipeline and soil in case of temperature variations and ground displacements. Thermal stress is estimated from a heat transfer analysis considering the phase change in the soil using COMSOL. Soil-pipeline interaction based on 1984 ASCE Guidelines [1] is used for considering the effects of ground movements. The combined stress on the pipeline is estimated as a function of burial depth and is presented in a curve for design purposes. Numerical analysis by ABAQUS shows the adequacy of the presented curve.