第三方挖掘作用下PE燃气管道失效行为研究

针对挖掘破坏导致的城镇燃气管道失效，开展了挖掘作用下管道力学失效机理分析。考虑管土接触作用，建立了城镇燃气PE管道在挖掘齿作用下的三维力学响应分析模型，分析了典型工况下管道的失效过程，讨论了基于应力准则与基于应变准则等2种失效准则的适用性，并开展了影响因素分析。结果表明:机械齿作用下管道主要失效位置为机械齿与管道接触位置两端；采用基于应变的失效准则可以更好地利用PE管材的塑性性能；机械齿的作用位置对管道力学响应影响较小；管径和壁厚的增大能减小管道内的应力，同时能够减小管道的截面椭圆度；内压的改变对管道的力学响应几乎没有影响。以上结果可为城镇燃气管道的力学失效分析与安全评价提供一定的参考。

Failure behavior analysis on PE gas pipeline under the effect of third-party excavation

Aiming at the failure of urban gas pipeline caused by excavation damage, the mechanical failure mechanism of pipeline under the effect of excavation was analyzed. A three-dimensional mechanical response analysis model for urban PE gas pipeline under the effect of excavation teeth was established considering the pipe-soil contact effect. The failure process of pipeline under typical working conditions was analyzed, then the applicability of two failure criteria, including stress based criterion and strain based criterion, was discussed, and the influence factors were analyzed. The results showed that the main failure positions of pipeline under the effect of excavation teeth are the both ends of contact positions between mechanical teeth and pipeline. Adopting the failure criterion based on strain can better utilize the plastic performance of PE pipeline material. The action position of mechanical teeth has little influence on the response of pipeline. The increase of pipeline diameter and wall thickness can decrease the stress in the pipeline, and decrease the sectional ovality of pipeline at the same time. The change of internal pressure has almost no influence on the mechanical response of pipeline. The results can provide a certain reference for mechanical failure analysis and safety evaluation of urban gas pipeline.