Response Analysis For Buried Pipeline In Liquefied Soil

The soil liquefaction is one of the important factors which makes the buried piplines damaged. Buried piplines are also a very important group of lifeline engineering system and it plays a crucial role on city life and industrial and agricultural production. Therefore, in order to prevent and decrease the buried piplines'destruction effectively due to the soil liquefaction, it has important scientific and practical significance to bulit proper calculation model for studying responses of buried pipelines in liquefied soil and apply the conclusion to engineering practice.In this paper, the respones of buried pipelines induced by soil liquefication is stuied numerically. Firstly, the paper introduces the feature of earthquake damage and influence factors of buried pipelines, reviews current state of reseach on buried pipelines in liquefied soil systematically. The ground soil liquefication mechanism, influence factors, method of evaluating liquefaction and calculation method after soil liquefaction are discussed; Then the formulate is deduced for the floating response of buried pipeline. The pipline is decrietized into four nodes thin shell element structure, and the soil around the pipeline is modeled by nonlinear spring. The pipeline floating is achieved by loading the linear displacement. The paper gets the basic laws of the stress and deformation of pipeline; After that, eight nodes solid elements are meshed for the non-liquation soil and the pipeline, and the soil spring model is used for liquefied soil. Between the soil and pipeline, the nolinear contact pair is created for better simulating the soil. The buoyant force is applied to analysis the floating response of buried pipeline, and the different parameters of influence factors are considered, such as the length of liquefied area, the axial force on the pipeline, the aquivalent stiffness of the soil spring, the diameter and thickness of pipeline, the internal pressure of pipeline, and the buried depth of pipeline. Finally, an effective measures that is setting the supporting piers on the pipeline of liquefied area for decreasing the pipeline floating is presented by caculation of examples.The study gets some useful results by numerical calculation:the maximum strain appeared at the Juncture of liquefied area and unliquefied area; the increase of the length of liquefied area makes the floating response of buried pipeline greater; the increase of the axial force on the pipeline makes the floating response of buried pipeline greater; the increase of the aquivalent stiffness of the soil spring makes the floating response of buried pipeline greater smaller; the increase of the diameter and thickness of pipeline makes the floating response of buried pipeline greater; the increase of the internal pressure of pipeline makes the floating response of buried pipeline greater; the decrease of the buried depth of pipeline makes the floating response of buried pipeline smaller, but if the buried pipeline is too shallow, it can cause the pipeline emerge to the ground easily; to reduce the the floating response of buried pipeline, the supporting piers can be set on the pipeline of liquefied area. the spacing of buttress gets smaller and the length of buttress along the pipeline gets longer, the floating response of buried pipeline gets smaller.In the end, the summary is made, some problems and possible future research directions which need to be studied on buried pipelines in liquefied soil are discussed.