地质沉降作用下埋地玻璃钢管道的力学行为

Study on mechanical behaviors of buried FRP pipeline under geological sedimentation

【目的】相比于常规金属管道,玻璃钢管道具有强度高、质量轻等优点,目前已逐渐在油气田站场集输领域投入应用。作为埋地管道面临的常见地质灾害,地质沉降对埋地玻璃钢管道的安全运行具有较大威胁,分析地质沉降作用下玻璃钢管道力学性能变化规律及其影响因素,有助于对保障其安全服役提供理论指导。【方法】采用有限元软件ABAQUS,考虑玻璃钢管道管材的多层非线性各向异性,建立埋地玻璃钢管道模型。基于Hashin失效准则研究不同缠绕角度、沉降量、土壤环境下玻璃钢管道基材与纤维压缩、拉伸初始化准则最大值的分布规律。【结果】在地质沉降作用下,基材的压缩、拉伸初始化准则最大值相应大于纤维的压缩、拉伸初始化准则最大值,基材破坏模式对管道整体性能的影响更大;不同铺层缠绕角度工况下,隔层角度为土30°时管道失效系数最低,更有利于管道安全服役;管道各项失效系数的峰值均位于沉降过渡区中部位置附近及过渡区与沉降区交界处;土壤环境的改变对管道中间层失效系数影响最大。【结论】利用ABAQUS复合铺层模块能够较好地模拟玻璃钢复合管材的特性,相关结果可为玻璃钢管道铺层缠绕选型与地质沉降工况管道安全情况分析提供理论依据。

[Objective]Compared to conventional metal pipelines,fiber-reinforced plastic(FRP)pipelines demonstrate superior strength and lightweight properties.They have been progressively integrated into the station gathering and transmission segment within oil and gas fields.Among the prevalent geological hazards encountered by buried pipelines,geological sedimentation presents a substantial threat to the safe operation of buried FRP pipelines.Hence,assessing the mechanical behavior variations of FRP pipelines under geological sedimentation and the pertinent influencing factors are crucial for providing theoretical guidance to ensure their safe operation.[Methods]A buried FRP pipeline model was established,utilizing the finite element sofware ABAQUS,and taking into account the multi-layer nonlinear anisotropy of FRP pipelines.Hashin's failure criteria were employed to explore the maximum distribution of the compression and tension initiation criteria for both the FRP pipeline matrix and fiber at varying winding angles,settlements,and soil conditions.[Results]Under geological sedimentation,it was observed that the maximum values in the compression and tension initiation criteria for the matrix were higher compared to those of the fiber.This disparity results in larger impacts from matrix failure on the overall performance of pipelines.Across different lay-up winding angles,the lowest pipeline failure coefficient occurred at the interlayer angle of±3o,creating favorable conditions for the safe operation of pipelines.The peak values of various failure coefficients were primarily concentrated near the middle of the settlement transition zone and at the boundary between the transition and settlement zones.Notably,alterations in soil conditions were found to exert the most significant influence on the failure coefficient of the pipeline intermediate layers.[Conclusion]The ABAQUS composite layup module has proven effective in simulating the characteristics of FRP composite pipes.The simulation outcomes provide a theoretical foundation for choosing an appropriate layup winding type and conducting safety analysis for FRP pipelines under geological settlement conditions.