【摘要】 埋设的海底管线在高温、高压下较易发生竖直向屈曲大变形,保证足够的埋置深度是海洋工程中克服管线出现竖直向屈曲变形的有效手段之一。因此,研究土体能够提供给管线的抗力及在管线竖直向上拱起过程中土体抗力的变化规律,对管线的抗屈曲大变形设计具有重要的意义。结合渤海湾海底地表土质特点选取细砂进行了室内管-土相互作用试验,测量了不同直径、不同埋置率(上覆土厚与管线直径的比)的试验管段,在竖直向上运动过程中所受到的土抗力;采用数值方法有效地模拟了试验中管段的受力变化过程。进而将结果推广,得到了砂土中常用直径管线受到的土抗力大小及作用规律。试验及数值模拟结果表明,管线竖直向上运动时,土抗力的发挥随竖向位移增加而迅速增大达到峰值,峰值抗力所需要的位移随管径与埋置率的增加而增大;实际工程中峰值抗力对应的管线位移约为管径的0.1倍,计算结果可供管线设计时参考。更多还原

【Abstract】 In-service hydrocarbons must be transported at high temperature and pressure to ease the flow and prevent solidification of the wax fraction.The buckling of submarine pipelines occurs due to the introduction of axial compressive forces caused by the constrained expansions set up by thermal and internal pressure actions.Vertical buckling is particularly of interest with respect to buried submarine pipelines.To lay pipeline in trench with a certain depth is an effective measure to avoid vertical thermal upheaval buckling.Therefore,it is very important that study of the maximum resistance which soil can provide as well as the soil resistance changing procedure with the pipeline buckling amplitude.Fine sand was chosen as the soil medium in view of Bohai Gulf conditions.A model test was carried out to establish the relationship between soil resistance and pipeline displacement in laboratory.The pipeline segments with different diameters and different covered depths were used in the test.The soil resistance and the pipe segments vertical displacement were both recorded in great details.Then the numerical analyzing methodology was applied to simulate the model test procedure.Test data and analyzing results show that when the pipeline doing vertical uplift movement,process of soil resistance exertion can be affected by the buried rate of pipeline,when the buried rate is small,soil resistance decreases until stable after reaching peak;while when buried rate is large,the soil resistance doesn’t significantly reduced after its peak.In the practice,the maximum soil resistance can be gained when the pipeline upward displacement reaches to approximate 0.1D.更多还原