Performance assessment of buried pipelines considering soil-structure interaction

考虑土壤-结构相互作用的埋地管道性能评估

• 批准号: RGPIN-2018-03886
• 负责人: Dhar, Ashutosh
• 金额: $ 1.89万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=649201
• 关键词: Performance; assessment; buried; pipelines; considering

Buried pipelines are widely used as an economic means of transporting liquid and gas. Pipeline failure occurs every year in Canada and worldwide resulting in significant economic and environmental consequences. Factors contributing to pipeline failure include local defects resulting from manufacturer imperfection, dents during construction/operation, and corrosion; and operational/environmental loads. Structural failure of the pipe often initiates locally and propagates gradually or catastrophically, depending upon crack propagation behaviour, through interaction with surrounding soil. This research investigates soil-pipe interaction for the assessments of the structural failure initiation and propagation in a pipe wall due to local defects and the ground loads on pipelines, for municipal cast iron water mains and steel energy pipelines, respectively. For structural failure assessment, finite element modeling techniques will be developed to model crack propagation in the pipe wall using fracture mechanics. The point of initiation of a crack will be defined by creating small defects of different shapes on the pipe and/or by increasing stress concentration locally using a void in the backfill and/or applying concentrated forces simulating sharp objects (rock pieces) in the bedding. Pipe material properties (i.e., elastic parameters, strain-rate dependent stress-strain relations and fracture toughness) for the analysis will be determined using laboratory tests with specimens extracted from pipe samples. For modeling the ground load during axial pullout, finite element modeling will be performed with simulation of large deformation and strain localizations in the soil surrounding the pipeline. The stress–strain behaviour of soil will be modeled through development of new constitutive models capturing the pre-peak hardening, post-peak softening, relative density and confining pressure dependent behaviour of sand. For the constitutive model development, laboratory tests will be conducted with particular attention to the soil behaviour at a low stress level, because the stress around the pipelines is generally lower than the expected stress in typical geotechnical problems.******The understanding of the failure mechanisms and the loads from this research can be used to develop novel design guidelines for the pipelines. Outcomes of this research will thus contribute towards rational design of municipal and energy pipelines and thus to the minimization of pipeline failure. Two doctoral, three Masters and two undergraduate students will be supported through the proposed NSERC Discovery grant.

埋地管道被广泛用作运输液体和天然气的经济手段，在加拿大和世界范围内每年都会发生管道故障，导致重大的经济和环境后果，包括制造商缺陷造成的局部缺陷、施工/运营期间的凹痕。和腐蚀；以及管道的操作/环境载荷通常会在局部发生，并通过与周围土壤的相互作用逐渐或灾难性地扩展，具体取决于裂纹扩展行为。分别针对市政铸铁水管和钢制能源管道，评估由于局部缺陷和管道地面荷载而导致的管壁结构失效的发生和扩展。对于结构失效评估，将开发有限元建模技术。使用断裂力学模拟管壁中的裂纹扩展，通过在管道上创建不同形状的小缺陷和/或通过使用回填中的空隙和/或应用来局部增加应力集中来定义裂纹的起始点。模拟尖锐物体（岩石用于分析的管道材料特性（即弹性参数、应变率相关的应力-应变关系和断裂韧性）将通过从管道样本中提取的样本进行实验室测试来确定，以模拟轴向期间的地面载荷。拔出，将通过模拟管道周围土壤的大变形和应变局部化来进行有限元建模，将通过开发捕获峰值前硬化的新本构模型来模拟土壤的应力应变行为。沙子的峰后软化、相对密度和围压相关行为对于本构模型的开发，将进行实验室测试，特别关注低应力水平下的土壤行为，因为管道周围的应力通常低于管道周围的应力。典型岩土工程问题中的预期应力。******本研究对失效机制和载荷的理解可用于制定新的管道设计指南，从而有助于市政和市政工程的合理设计。能源管道，从而两名博士生、三名硕士生和两名本科生将通过拟议的 NSERC 发现补助金获得支持。