Pipelines in operation often experience various loadings due to operational and environmental conditions. Large strain may be accumulated in the pipes under these loadings, and it may eventually induce local buckling or even fractures on the pipes. It is a common practice that a stress relief procedure is applied to a pipe by removing the soil around the pipe, allowing the pipe to spring back to a zero load state. The frequency of stress relief procedure is dependent on the severity of loading and soil conditions. This project is intended to study the behavior of buried pipes subjected to repeated stress relief procedures. The buried pipeline at Pembina River Crossing in Lodgepole, Alberta was simulated using the finite element method and the results were compared with field measured data. The pipeline at Pembina River Cross is situated at the active soil movement locations. A finite element model was developed to simulate the slope movement and the pipeline response. The correlation between soil movement and precipitation was investigated. With shell elements for pipe, 3D-solid elements for soil, this model captures the global and local behavior of pipeline. Soil-pipe interaction was simulated by setting a weak layer of soil surrounding the pipeline. The model incorporates nonlinear material, slope soil creep and water table change. Modified Drucker-Prager Cap Model was applied to soils based on direct shear test results. The finite element model was calibrated by slope indicator data and strain gauge data with satisfactory agreement. The model was used to simulate the strain accumulation and the stress relief in the pipeline, before and after the stress relief operation. Reasonable agreement was achieved when compared to the field data. The model can be used to further understand the behavior of pipe under repeated soil movement and stress relief procedure. It can also be used to develop the optimum stress relief procedure and operating schedule.
展开▼
机译：操作中的管道经常由于运营和环境条件而经常遇到各种负荷。大应变可以在这些载荷下累积在管道中，并且最终可能在管道上诱导局部屈曲甚至骨折。通过在管道周围除去土壤，将应力浮雕程序施加到管道上是一种常见的做法，使得管道弹回零负载状态。应力浮雕程序的频率取决于负载和土壤条件的严重程度。该项目旨在研究经过反复应力救济程序的埋地管的行为。在艾伯塔省在Lodgepole的Pembina河流过桥的埋藏管道被使用有限元方法模拟，结果与现场测量数据进行了比较。 Pembina River Cross的管道位于主动土机场。开发了一个有限元模型来模拟斜坡运动和管道响应。研究了土壤运动与沉淀之间的相关性。使用管道的壳体元件，土壤的3D固体元素，该模型捕获了管道的全球和局部行为。通过设定围绕管道周围的土壤层来模拟土管相互作用。该模型包括非线性材料，斜坡土壤蠕变和水位变化。改进的DRUCKER-PRAGER CAP模型应用于直接剪切测试结果的土壤。通过倾斜指示器数据和应变仪表数据校准有限元模型，具有令人满意的协议。该模型用于模拟压力浮雕操作前后管道中的应变累积和应力浮雕。与现场数据相比，合理的协议是实现的。该模型可用于进一步了解在重复的土壤运动和应力浮雕过程下管道的行为。它也可用于开发最佳应力释放程序和操作程序。
展开▼
