Advanced Assessment of Pipeline Subjected to Downslope Movements at River Crossing: Effect of Concrete Coating

Abstract The long linear nature of buried pipelines results in the risk of interaction with a range of geotechnical hazards including downslope movements at pipeline stream and river crossings. Ground movement induced by these geotechnical hazards can subject a pipeline to displacement controlled axial, lateral, vertical and bending loading. These geotechnical hazards can result in the accumulation of axial tensile and compressive strains in the pipe. Therefore, calculation of pipe strain demand and strain capacity considering the site condition and the appropriate slope movement mechanism is necessary in assessing the pipeline integrity to support maintenance management. It is a common practice to use weight concrete coating to provide negative buoyancy for river crossing application. The pipeline concrete coating design may extend to the toe of the slope and end adjacent to the pipeline location experiencing displacement (bending deformations). The discontinuity of the concrete coating may result in strain concentration at the end of the concrete coating when the pipeline is subject to plastic deformation. To address this without exaggerating the stiffening effect of the concrete, it is necessary to account for pipe concrete coating properties and for the slip between the concrete-pipe interface. This paper presents a case study analyses of slope movement using a novel 3D continuum model to illustrate the detailed information that can be derived from geotechnical hazard simulation. The model was calibrated and validated for the assessment of pipe-soil interaction modeling of geotechnical events. The analyses presented in this paper provide insights into the effects of ground movement on pipeline integrity near river crossing. The analyses highlight the effects of the pipe concrete weight coating on the pipeline response at the crossing that may affect the remedial action decisions.