FLOW-PIPE-SEEPAGE COUPLING ANALYSIS OF SPANNING INITIATION OF A PARTIALLY-EMBEDDED PIPELINE  

作　　者：GAO Fu-ping LUO Cheng-cai 

机构地区：[1]Key Laboratory for Hydrodynamics and Ocean Engineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China [2]Centre for Offshore Foundation Systems, The University of Western Australia, Nedlands, WA 6907, Australia

出　　处：《Journal of Hydrodynamics》2010年第4期478-487,共10页水动力学研究与进展B辑（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No. 10532070);the Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KJCX2-YW-L02)

摘　　要：The initiation of pipeline spanning involves the coupling between the flow over the pipeline and the seepage-flow in the soil underneath the pipeline.The pipeline spanning initiation is experimentally observed and discussed in this article.It is qualitatively indicated that the pressure-drop induced soil seepage failure is the predominant cause for pipeline spanning initiation.A flow-pipe-seepage sequential coupling Finite Element Method（FEM） model is proposed to simulate the coupling between the water flow-field and the soil seepage-field.A critical hydraulic gradient is obtained for oblique seepage failure of the sand in the direction tangent to the pipe.Parametric study is performed to investigate the effects of inflow velocity,pipe embedment on the pressure-drop,and the effects of soil internal friction angle and pipe embedment-to-diameter ratio on the critical flow velocity for pipeline spanning initiation.It is indicated that the dimensionless critical flow velocity changes approximately linearly with the soil internal friction angle for the submarine pipeline partially-embedded in a sandy seabed.The initiation of pipeline spanning involves the coupling between the flow over the pipeline and the seepage-flow in the soil underneath the pipeline.The pipeline spanning initiation is experimentally observed and discussed in this article.It is qualitatively indicated that the pressure-drop induced soil seepage failure is the predominant cause for pipeline spanning initiation.A flow-pipe-seepage sequential coupling Finite Element Method（FEM） model is proposed to simulate the coupling between the water flow-field and the soil seepage-field.A critical hydraulic gradient is obtained for oblique seepage failure of the sand in the direction tangent to the pipe.Parametric study is performed to investigate the effects of inflow velocity,pipe embedment on the pressure-drop,and the effects of soil internal friction angle and pipe embedment-to-diameter ratio on the critical flow velocity for pipeline spanning initiation.It is indicated that the dimensionless critical flow velocity changes approximately linearly with the soil internal friction angle for the submarine pipeline partially-embedded in a sandy seabed.

关 键 词：submarine pipeline pipeline spanning seepage failure flow-pipe-seepage coupling 

分 类 号：TU452[建筑科学—岩土工程] TU756.44[建筑科学—土工工程]