Buried Pipelines: Settlement Modification and Load Transfer

Flexible jointed buried pipelines, when subject to conditions that result in differential settlements, transfer loads along the pipeline which in turn modify contact pressures and settlements for each length of pipe. Angular distortion between the individual lengths of pipe thus results in opening joints and creating a potential for leakage. Expressions are derived, based on certain assumptions, that permit the determination of the transfer loads, as well as the resulting contact pressures, pipe settlements, and angular distortions between individual pipe sections adjacent to structures. Consideration is given in the derivations to the transitional loading on pipe which is a consequence of its support at a structure. The procedures for load transfer determinations are also applied to pipelines subject to concentrated surface loadings. Additionally, the theory is extended to the case of buried pipelines having horizontal unbalanced thrust at fittings.