渤海湾软黏土对埋设海底管线约束力的研究

Soil resistance acting on buried pipelines in Bohai Bay soft clay

海底管线与地基土体的相互作用在管线设计中至关重要,针对海底管线在温度应力下发生整体屈曲变形时可能产生的竖直向上、水平向及轴向运动,研究地基土体对管线的约束力。结合渤海湾海底地表土质特点选取软黏土开展室内管土相互作用试验,研究不同直径、不同埋置率(上覆土厚与管线直径的比)的管线竖直向上运动、水平向运动以及轴向运动时土体抗力的发挥过程,采用数值方法对模型试验进行模拟,进而将模拟方法扩展应用于对实际工程管线的模拟分析。试验结果表明与管线轴向运动相比,当管线发生竖直向与水平向运动时,其所受土抗力的大小受到管线直径与埋置率的影响显著;综合室内试验数据及数值模拟分析结果,提出了黏土对管线最大约束力及达到最大约束力所需位移的计算公式。

During the design of submarine pipelines, it is a crucial problem to determine the interaction between the pipeline and the subsoil. The uplift, lateral and axial soil resistances acting on the pipelines are investigated considering the moving directions of the pipelines in the thermal overall buckling analysis. Soft clay is chosen as the supporting medium in view of geotechnical conditions in Bohai Gulf. A series of model tests are carried out to facilitate the establishment of substantial data base for a variety of burial pipeline topologies. In the tests, the pipes with different diameters are buried with different depth-to-diameter ratios. The uplift, lateral and axial resistances are recorded during the tests. Based on the test data, a numerical method is established and used to analyze an actual dimensional pipeline in practice. The test results show that the uplift and lateral soil resistances depend on the pipe diameters and cover depth more greatly than the axial soil resistance. According to the test data and numerical results, the experimental formulae are proposed to determine the maximum soil resistance and the corresponding displacement of pipelines for all their three moving directions.