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.

埋入的管道被广泛用作运输液体和天然气的经济手段。管道故障每年在加拿大和全球发生，从而产生重大的经济和环境后果。导致管道故障的因素包括制造商缺陷导致的局部缺陷，施工/操作期间的凹痕和腐蚀；和操作/环境负荷。管道的结构性故障通常会在本地引发，并通过与周围土壤的相互作用而逐渐或灾难性地传播，具体取决于裂纹的繁殖行为。这项研究调查了土壤管的相互作用，以评估由于局部缺陷和管道上的地面负载，分别用于市政铸铁水管和钢能管道，这是由于局部缺陷和管道上的地面负荷而导致的。对于结构性故障评估，将开发有限元建模技术，以使用断裂力学对管壁中的裂纹传播进行建模。裂纹的起始点将通过在管道上产生不同形状的小缺陷和/或通过使用回填充中的空隙和/或施加模拟床上用品中的尖锐物体（岩石）的浓缩力来局部增加应力浓度来定义。管道材料特性（即弹性参数，应变率依赖性应力 - 应力关系和断裂韧性）将使用从管道样品中提取的标本进行实验室测试来确定分析。为了在轴向拉力过程中建模地面载荷，将通过模拟管道周围土壤中的较大变形和应变局部化进行有限元建模。土壤的应力扭转行为将通过开发新的构型模型来建模，从而捕获前峰硬化，峰值软化，相对密度和隔压依赖压力依赖性行为。对于组成型模型的开发，将特别注意低应力水平的土壤行为，因为管道周围的应力通常低于典型岩土技术问题中的预期应力。因此，这项研究的结果将有助于市政和能源管道的合理设计，从而有助于最小化管道故障。拟议的NSERC Discovery Grant将支持两个博士学位，三名硕士和两名本科生。