堆载作用下埋地管道应力影响因素及失效荷载研究

Research on stress influencing factors and failure load of buried pipeline under ground load

为探究地面堆载导致埋地油气管道失效的事故影响因素,通过对管道在堆载作用下的工程案例进行概化,以X70管道为研究对象,采用有限元软件建立管道在堆载作用下的三维模型,采用理论计算验证模型的可行性,开展管道应力与变形分析,探讨不同的堆载强度、管道埋设深度、下卧层土体杨氏模量、管道内压与堆载偏移距离对管道应力的影响,同时开展多因素耦合研究。研究结果表明:深埋管道会促进附加应力向两端扩散,管道中心部位以外的应力值呈现为深埋>浅埋;当下卧层杨氏模量大于20 MPa后,管道偏于安全;内压在0~2 MPa时,可以抵消部分堆载对管道的影响,内压大于2 MPa后,管道应力整体增大,此时管道应力由内压主导;得到不同管道埋深与不同下卧层土体杨氏模量耦合工况下X70管道失效时的堆载强度。研究结果可为埋地管道在堆载作用下的安全防护问题提供参考。

In order to explore the accident influencing factors of buried oil and gas pipeline failure caused by ground load,through generalizing the engineering case of the pipeline under the action of ground load,and taking the X70 pipeline as the research object,the finite element software was used to establish the three-dimensional model of the pipeline under the action of ground load.The feasibility of the model was verified by theoretical calculation,and the pipeline stress and deformation analysis was carried out.The influence of different ground load strength,pipeline burial depth,Young’s modulus of underlying soil,pipeline internal pressure and load offset distance on pipeline stress was discussed,and the multi-factor coupling study was carried out.The results showed that the deep buried pipeline would promote the additional stress to spread to both ends,and the stress value outside the center of pipeline was deep buried>shallow buried.When the Young’s modulus of underlying soil was greater than 20 MPa,the pipeline was on the safe side.When the internal pressure was between 0~2 MPa,the influence of part of the ground load on the pipeline could be offset,and when the internal pressure was greater than 2 MPa,the pipeline stress would increase as a whole,at this time,the pipeline stress was dominated by the internal pressure.The ground load strength of the X70 pipeline at failure under the coupling conditions of different buried depths of pipeline and different Young’s modulus of underlying soil was obtained.The results can provide a certain reference for the safety protection of buried pipelines under the action of ground load.