Describes an algorithm is developed for deducing the longitudinal or axial strain from geometry pig measurements of a laterally displaced pipeline; often caused by geohazards. The development is limited to those lateral displacements of the pipeline that results in a predominantly transverse loading; i.e., the induced transverse component of the loading is much greater than its axial component. The emphasis is upon evaluating inelastic straining that accompanies large lateral displacement of the pipeline. The induced extensional strain is found to vary linearly with the change in curvature of ...
Describes an algorithm is developed for deducing the longitudinal or axial strain from geometry pig measurements of a laterally displaced pipeline; often caused by geohazards. The development is limited to those lateral displacements of the pipeline that results in a predominantly transverse loading; i.e., the induced transverse component of the loading is much greater than its axial component. The emphasis is upon evaluating inelastic straining that accompanies large lateral displacement of the pipeline. The induced extensional strain is found to vary linearly with the change in curvature of the pipeline. The validity of the approach is established through favorable comparisons of the predictions for the extensional strains with those determined from buried pipeline finite element simulations of various displaced pipe configurations, pipe geometries, and loading amplitudes. Since the algorithm relies only upon measurements of the geometry of the displaced pipeline, it is independent of the pipe's and soil's material properties, pipe-soil interaction, and the loading conditions.
Benefit: The efficacy of the algorithm is demonstrated by performing a large matrix of finite element simulations of displaced pipelines of different geometries subjected to block subsidence, landslides intersecting the pipeline at varying angles, fault crossings at different angles and different loading states, and comparing the analytical strains with the strains deduced from digital pig measurements of the curvature of the deformed pipeline. In this regard, the finite element simulations serve the role of surrogate geometry pig measurements. These comparisons are used to establish the resolution of the change in curvature measurement required of a geometry pig to produce a reliable estimate for the longitudinal strain in a displaced pipeline. An error analysis is also performed to establish the relative error as a function of the curvature measurement gage length, a characteristic feature-length, and the abruptness of the displaced shape of the pipeline.