输气管道第三方破坏数值分析及安全评价方法

为保障天然气管道安全运行,减少天然气管道发生第三方破坏泄漏带来的严重危害,提高破损管道的防控力度,通过经典赫兹接触理论,采用有限元仿真软件,建立第三方挖掘机斗齿作用管道的数值模型,研究了不同斗齿冲击角度和冲击深度对管道的损伤程度。结果表明:随着挖掘机斗齿吃入深度增大,管道内外壁面的变形越大,卸载内压后管道凹坑变形更加明显。基于输气管道残余应力研究分析,考虑凹坑深度及应力综合评价,对破损管道进行了系统分析。结论以管道应变的6%为临界值,管道外表面凹坑深度的最大值为参考,给出破损管道更换的评价标准。最后,对某管段施工过程中挖掘机斗齿的影响进行了风险评价分析,为实际现场输气管道第三方破坏的风险防控预案提供科学依据。

Numerical Analysis and Safety Evaluation Method of Third Party Damage in Gas Pipeline

In order to ensure the safe operation of natural gas pipelines, reduce the serious harm caused by third-party damage and leakage of natural gas pipelines, and improve the prevention and control of damaged pipelines. Based on the classical Hertz contact theory and ANSYS finite element methods(FEM), the numerical model of bucket teeth acting on the pipeline was established. The damage degree of different bucket teeth impact angles and impact depths to the pipeline was studied and analyzed. The results show that the deformation of the inner and outer walls of the pipeline is greater with the increase of the tooth depth of the excavator, and the pit deformation of the pipeline is more obvious after unloading the internal pressure. Based on the research and analysis of residual stress of gas pipeline, this paper considered the comprehensive evaluation of pit depth and stress, and systematically analyzed the damaged pipeline. The paper concludes that the critical value of pipeline strain is 6%, and the maximum pit depth on the outer surface of pipeline is taken as a reference, and the evaluation standard of damaged pipeline replacement is given. At last, the risk assessment analysis is made on the influence of bucket teeth of excavator during the construction of some pipe section. It provides scientific basis for the risk prevention and control plan of the third-party damage of the on-site gas pipeline.