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.

埋地管道作为一种经济的液体和天然气输送方式被广泛使用。加拿大和世界各地每年都会发生管道故障，造成重大的经济和环境后果。导致管道失效的因素包括由制造商缺陷、施工/运营过程中的凹痕和腐蚀造成的局部缺陷；以及运行/环境负荷。管道的结构破坏通常是局部开始的，并通过与周围土壤的相互作用逐渐或灾难性地扩展，这取决于裂纹的扩展行为。本研究通过土-管相互作用的研究，分别对城市铸铁自来水管道和钢结构能源管道的局部缺陷和地面荷载引起的结构破坏在管壁中的起始和扩展进行了研究。在结构失效评估方面，将发展有限元模拟技术，利用断裂力学对管壁中的裂纹扩展进行模拟。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洞和/或在垫层中施加模拟尖锐物体(岩石块)的集中力来局部增加应力集中来定义。用于分析的管道材料特性(即弹性参数、与应变率相关的应力-应变关系和断裂韧性)将通过从管道样品中提取的样品进行实验室测试来确定。为了模拟轴向拉拔过程中的地面荷载，将进行有限元模拟，模拟管道周围土体的大变形和应变局部化。土的应力-应变行为将通过开发新的本构模型来模拟，该模型捕捉了砂土的峰前硬化、峰后软化、相对密度和围压依赖行为。对于本构模型的开发，将特别注意低应力水平下的土体特性，因为管道周围的应力通常低于典型岩土问题的预期应力。*本研究对破坏机制和荷载的理解可以用于制定新的管道设计指南。因此，本研究的成果将有助于市政和能源管道的合理设计，从而将管道故障降至最低。两名博士、三名硕士和两名本科生将通过拟议的NSERC发现基金获得资助。