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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=681617
• 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 stressstrain 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输送液体和气体的经济手段。加拿大和世界各地每年都会发生管道故障，造成严重的经济和环境后果。导致管道故障的因素包括制造商缺陷造成的局部缺陷、施工/运行过程中的凹痕以及腐蚀；和操作/环境负载。管道的结构失效通常从局部开始，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。本研究研究了土壤-管道相互作用，以评估市政铸铁水管和钢制能源管道因局部缺陷和管道地面荷载导致的管壁结构失效萌生和传播。对于结构失效评估，将开发有限元建模技术，利用断裂力学对管壁中的裂纹扩展进行建模。裂纹的起始点将通过在管道上产生不同形状的小缺陷和/或通过使用回填中的空隙增加局部应力集中和/或施加模拟基床中尖锐物体（岩石碎片）的集中力来定义。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）将通过实验室测试和从管道样品中提取的样本来确定。为了对轴向拉拔过程中的地面载荷进行建模，将通过模拟管道周围土壤中的大变形和应变局部化来进行有限元建模。将通过开发新的本构模型来模拟土壤的应力应变行为，该模型捕获沙子的峰前硬化、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典型岩土问题中的预期应力。******理解这项研究中的失效机制和载荷可用于制定新颖的管道设计指南。因此，这项研究的成果将有助于市政和能源管道的合理设计，从而最大限度地减少管道故障。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。