Soil–Pipeline Interaction of Hybrid-Segmented Systems under Axial Ground Movement

Abstract

Case studies of pipeline repairs following extreme ground movement events demonstrate how the displacement accommodating mechanisms of hybrid-segmented pipelines perform favorably (requiring less repairs to maintain serviceability) compared with traditional pipeline systems. Hybrid-segmented pipelines utilize a joint-locking mechanism that allows a pipe segment to move a prescribed displacement before engaging the next segment of pipe. Given the recent emergence of these technologies, there is a need to understand how these systems respond to relative movement between the pipeline system and soil because this interaction directly impacts the soil resistance accumulated along the joint and at the connections. Frictional resistance along a pipe barrel and the passive resistance developed at the face of an enlarged connection can be quantified for a single pipe segment; however, the development of these forces along a pipeline system, composed of multiple segments, is dependent on how the pipeline accommodates induced displacements. This study establishes an analytical framework that captures the displacement accommodation mechanisms of hybrid-segmented pipelines under axial ground movement and estimates the subsequent accumulations of resistance (frictional and passive) along the system. The proposed framework determines how a series of pipe segments engage and the subsequent total resistance developed based on inputs for pipe, connection, and soil properties. The proposed framework is validated with established numerical models and previous analytical approaches, demonstrating favorable comparisons. Although previous analytical models can estimate the total geotechnical demands on a pipeline system for various levels of ground movement, the proposed analytical framework is able to capture the allowable displacement and joint-locking mechanisms that uniquely differentiate hybrid-segmented systems from traditional pipelines. The analytical framework presented in this study can be used by designed engineers to make informed decisions on which pipeline systems are best suited for various conditions and ground movement scenarios.