场地沉陷作用下埋地管道屈曲反应分析

Buckling response analysis of buried pipelines subjected to the site soil settlement

土体沉陷是引起埋地管道破坏的重要原因之一,它会引起穿越该沉陷区域的大口径地下管道屈曲失稳,使管道在没有达到拉伸或剪切强度前便退出工作。将管道与周围土体从半无限土体介质中共同取出,建立沉陷作用下的管土相互作用模型。管道以薄壳单元模拟,土体采用实体单元进行离散,采用特征值屈曲分析方法对沉陷区域埋地管道的屈曲稳定性进行了分析,给出了管道发生屈曲时的屈曲模态及对应的沉降量。研究沉陷区长度、管道埋深、管径、壁厚及场地条件等对管道屈曲反应的影响。在文中所用模型与假设条件下发现地下管线埋深较浅时更易发生屈曲失稳,管道径厚比越大管道越易发生屈曲,场地土体越硬管道越易发生屈曲失稳等结论。

The action of the soil settlement is one of the most important reasons leading to the failure of buried pipelines.The settlement may result in the buckling of large-diameter underground pipelines crossing the subsidence region,which makes the pipelines out of work before reaching the tensile and shear strength of the pipes.The pipelines and the surrounding soil are taken out together from the semi-infinite soil medium,and the pipe-soil interaction model under the site soil settlement is established.In the model,the pipeline is simulated by thin-shell element,while the surrounding soil is simulated by solid element.The linear eigenvalue buckling analysis method is adopted to study the buckling stability behavior of the pipe subjected to the soil settlement,and buckling modes of the pipes and corresponding soil settlement are gained.At last,some influencing factors on the buckling of the buried pipeline are studied,such as the length of the subsidence region,buried depth,pipe diameter and wall-thickness of pipe,etc.From the above adopted model and assumption,it is shown that the shallower the buried depth is,the more easily buckling the pipeline is;the larger the diameter-thickness ratio is,the more easily buckling the pipeline is;the harder the soil is,the more easily buckling the pipeline is.