洪水冲刷作用下悬空管道力学响应特性研究

Study on Mechanical Response Characteristics of Suspended Pipelines under Flood Scouring

长输管道常穿越河流湖泊等水文地域,在洪涝灾害频发地区,管道在洪水作用下可能发生弯曲折断等,从而造成严重事故。为研究在洪水作用下的管道力学行为,基于Morrison方程建立了洪水冲刷作用下的悬空管道数值模型,重点分析了典型影响因素对管道力学行为的影响。研究结果表明:管道悬空长度会明显影响管道的应力和轴向应变;悬空管道中部和端部均存在高应力区,但最大应力在管道端部,当悬空长度大于60 m,端部应力超过屈服极限;管道上下表面最大轴向应变都处于管道端部,且最大应变和最小应变关于管道中心近似呈中心对称;管道上表面受压,下表面受拉;管道应力和轴向应变随洪水速度和管道内压的增大而增大,随管道壁厚增大而减小。

Long-distance pipelines often cross hydrological areas such as rivers and lakes.In the areas with frequent flood disasters,the pipeline may bend and break under the action of flood,which will cause serious impact.To study the mechanical behavior of pipelines under the action of floods,a numerical model of suspended pipelines under the action of flood scouring is established based on the Morrison equation,and the effect of typical factors on the mechanical behavior of pipeline is analyzed.The study results show that the suspended length of the pipeline will obviously affect the stress and axial strain of the pipeline.There are high stress areas in the middle and the end of the suspended pipeline,but the maximum stress is at the end of the pipeline.When the suspended length is greater than 60 m,this position is easily reached yield strength.The maximum axial strain on the upper and lower surfaces of the pipeline are both at the end of the pipeline,and the maximum strain and the minimum strain are approximately centrosymmetric about the center of the pipeline.The upper surface of the pipeline is under pressure,and the lower surface of the pipeline is under tension.In addition,the stress and axial strain of the pipeline increase with the increase of flood velocity and pipeline internal pressure and decrease with the increase of the pipeline wall thickness.