落石冲击下局部裸露天然气管道力学分析

Mechanical Analysis of Partially Exposed Natural Gas Pipelines under Rockfall Impact

随着天然气管道在地质灾害易发区的大量敷设,洪水冲刷及落石冲击给天然气管道的安全运行带来极大的风险,落石冲击作用极易造成管道防腐层破损、管道局部变形失稳甚至破裂。为提升地质灾害易发区天然气管道安全运行管控水平,针对因洪水冲刷造成的局部裸露天然气管道,利用ABAQUS软件模拟落石对局部裸露天然气管道的冲击过程,采用单因素法分析了不同的管道裸露高度、管道壁厚、管道运行压力、落石半径和落石速度等工程条件下,局部裸露管道受落石冲击后,管道最大Mises应力随影响因素的变化规律。结果表明:局部裸露管道受落石冲击后,管道最大Mises应力总是出现在接触点,管道壁厚和管道最大Mises应力呈负相关,落石半径、落石冲击速度和管道内压同管道最大Mises应力存在显著的正相关性,落石半径是影响管道最大Mises应力的重要因素,当落石半径大于1.0 m时,最大Mises应力将超过管材X70的屈服强度。该分析结果可以为天然气管道在地质灾害易发区域的设计、敷设、工程防护及监测预警提供理论依据。

With a large number of natural gas pipelines being laid in geological disaster prone areas,flood scouring and rock-falling impact bring great risks to the safe operation of natural gas pipelines.The impact of falling rocks can easily cause damage to the pipeline anti-corrosion coating,local deformation and instability,and even rupture of the pipeline.In order to improve the safety operation and control level of natural gas pipelines in geological disaster prone areas,ABAQUS software is used to simulate the impact process of rockfall on partially exposed natural gas pipelines caused by flood erosion.The single factor method is used to analyze the variation law of the maximum Mises stress of a partially exposed pipeline under different engineering conditions such as exposed pipeline height,pipeline wall thickness,pipeline operating pressure,rockfall radius,and rockfall velocity after being impacted by rockfall.The results show that the maximum Mises stress of the partially exposed pipeline always appears at the contact point after being impacted by falling rocks.The pipeline wall thickness is negatively correlated with the maximum Mises stress of the pipeline,while the radius of falling rocks,impact velocity,and internal pressure of the pipeline have a significant positive correlation with the maximum Mises stress of the pipeline.The radius of falling rocks is an important factor affecting the maximum Mises stress of the pipeline.When the radius of the falling rock is greater than 1.0 m,the maximum Mises stress will ex-ceed the yield strength of pipe X70.The analysis results can provide theoretical basis for the design,laying,engineering protection,and monitoring and warning of natural gas pipelines in areas prone to geological disasters.