车载作用下埋地聚乙烯燃气管道力学特性

Mechanical Properties of Buried Polyethylene Gas Pipelines under Vehicle Loads

车辆载荷对含缺陷燃气管道应力—应变的影响较为显著。为研究车辆载荷作用下埋地含划痕缺陷管道的力学响应,搭建了“地面视频捕捉+地下传感器采集”试验平台,建立了含载荷、内压、缺陷深度系数及车速等因素的三维数理模型,通过试验验证了数值模型的合理性,并对各因素对管道的影响规律进行分析,明晰了车载作用下含缺陷聚乙烯燃气管道的力学响应特性。结果表明,车载作用下,埋地管道划痕上下端面产生方向相反的拉应力,导致缺陷处应力集中,应力大小从划痕前沿中心处向两端递减,缺陷深度系数越大,应力集中越明显;管道最大应力随载荷、内压、缺陷深度和车速的增加而增大,但车速对应力的影响程度相对较小。基于Von-Mises理论,分析了含缺陷管道的极限承载力,横穿道路铺设管道的极限承载力小于沿道路铺设管道;内压相同时,缺陷深度系数越大,管道极限承载力越小;缺陷深度系数相同时,内压越小,承载能力越大。

Vehicle load has a significant impact on the stress and strain of gas pipelines with defects.To study the mechanical responses of buried pipelines with scratch defects under vehicle load,a test platform of“ground video capture+underground sensor acquisition”was set up,and a three-dimensional mathematical model including load,internal pressure,defect depth coefficient,and vehicle speed was established.The rationality of the numerical model was verified through tests.The influences of various factors on the pipelines were analyzed,and the mechanical response characteristics of the defective polyethylene gas pipelines were clarified.The results show that,under the actions of the vehicle,the tensile stress in the opposite directions is generated on the upper and lower ends of the scratch,resulting to the stress concentration at the defect.The stress decreases from the center of the scratch front to both ends.The greater the defect depth factor,the more obvious the stress concentration.The maximum stress of the pipelines increases with the increase of load,internal pressure,defect depth,and speed,but the speed influence on the stress is relatively small.Based on the Von-Mises theory,the ultimate bearing capacity of the pipelines with defects was analyzed.The ultimate bearing capacity of the pipelines laid across the road is less than that laid along the road.With the same internal pressure,the greater the defect depth coefficient,the smaller the ultimate bearing capacity of the pipelines.With the same defect depth coefficient,the smaller the internal pressure,the larger the bearing capacity.