滑坡作用下埋地天然气管道的失效机理及预测

Failure mechanism and prediction for buried natural gas pipeline under landslide effects

  • 摘要:
    目的 滑坡作为中国最常见且最频繁的地质灾害之一,极易造成长输管道发生变形、破裂、泄漏甚至灾难性的爆炸事故,对滑坡作用下的管道失效进行研究可以更直观地评估管道的安全状态。
    方法 选取X80管道为研究对象,使用ABAQUS软件建立滑坡-管道有限元模型,将有限元模拟结果与机器学习相结合,构建秃鹰-极限学习机(Bald Eagle Search-Extreme Learning Machine, BES-ELM)模型,对滑坡作用下埋地天然气管道的力学响应与预测性能进行分析。采用多因素分析法,主要探讨了滑坡位移、滑坡宽度、管道内压、管道壁厚、土体黏聚力、土体内摩擦角及土体类型7种参数对管道等效应力的影响规律。
    结果 在滑坡位移作用下,管道受轴向拉力、压力的影响最为显著,当滑坡位移处于2.5~3.0 m时,管道最大等效应力易超过屈服强度,导致管道发生失效。在相同的滑坡位移影响下,管道内压、土体黏聚力及土体内摩擦角均与管道最大等效应力呈正相关关系,而管道壁厚与管道最大等效应力则呈负相关关系。滑坡宽度存在应力集中区,当滑坡宽度由10 m逐渐增至50 m时,管道最大等效应力呈先正、后负的非线性变化规律。在滑坡影响下,管道最危险部位并非固定不变,而是随着位移及其他不同因素的变化,在迎滑面与背滑面之间相互转移。
    结论 选取150组有限元数据,将BES-ELM模型与传统的极限学习机(Extreme Learning Machine, ELM)模型进行了滑坡作用下管道等效应力预测性能对比,BES-ELM模型预测效果较好,最大相对误差为1.06%、决定系数为0.977,且均方根误差预测结果也降低了65.18%,可将其作为快速识别管道等效应力的有效工具。在长输管道选线工作中,应对管道沿线地质条件进行调研,尽量避开潜在的滑坡影响范围或采取加固措施保护管道安全。

     

    Abstract:
    Objective As one of the most common geological hazards in China, landslides frequently cause deformation, rupture, leakage, and even catastrophic explosions along long-distance pipelines. Studying pipeline failures caused by landslides provides a valuable approach for more effectively evaluating the safety status of these pipelines.
    Methods Based on X80 pipes selected as the research subject, a finite element model of landslide-pipeline interactions was established using ABAQUS software. The simulation results were then integrated with machine learning techniques to develop a Bald Eagle Search-Extreme Learning Machine (BES-ELM) model. This model was employed to analyze the mechanical responses and predictive performance of buried natural gas pipelines affected by landslides. Through multi-factor analysis, the influence of seven factors on the equivalent stress in the pipes was explored: landslide displacement, landslide width, internal pipeline pressure, pipeline wall thickness, soil cohesion, internal friction angle of soil, and soil type.
    Results Under the influence of landslide displacement, the most significant impacts on the pipes were primarily due to axial tension and pressure. When landslide displacements ranged from 2.5 m to 3.0 m, the likelihood of the pipes experiencing maximum equivalent stress exceeding their yield strength increased, consequently heightening the risk of pipeline failures. Within this displacement range, the internal pipeline pressure, soil cohesion, and the friction angle of the soil were positively correlated with the maximum equivalent stress in the pipes, while wall thickness exhibited a negative correlation. A stress concentration area was observed within the landslide widths. As the landslide width gradually increased from 10 m to 50 m, the maximum equivalent stress in the pipes displayed a non-linear change pattern, initially increasing before decreasing. Due to the landslides, different parts of the pipes encountered varying levels of risk, with the highest risk alternating between the front and back faces relative to the sliding direction as displacement and other factors changed.
    Conclusion A total of 150 groups of finite element data were selected to compare the predictive performance of the BES-ELM model and the traditional Extreme Learning Machine (ELM) model regarding pipe equivalent stress under landslide influence. The BES-ELM model produced superior prediction results, with a maximum relative error of 1.06%, a coefficient of determination of 0.977, and a root mean square error reduced by 65.18% compared to the traditional ELM model. This developed model has proven effective as a tool for quickly identifying equivalent stress in pipes. In summary, when selecting routes for long-distance pipelines, it is essential to investigate the geological conditions to bypass the influence range of potential landslides or to implement reinforcement measures to ensure pipeline safety.

     

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