Calculation of Maximum Allowable Free Span Length and Safety Assessment of the DF1-1 Submarine Pipeline  

作　　者：XU Jishang LI Guangxue Juan J. Horrillo YANG Rongmin CAO Lihua 

机构地区：[1]College of Marine Geo-scienees, Oeean University of China, Qingdao 266100, P. R. China [2]Key Laboratory of Submarine Sciences and Exploration Technology, the Ministry of Education of China, Qingdao 266100, P. R. China [3]Department of Maritime Systems Engineering, Texas A ＆M University at Galveston, Galveston, TX 77554, USA

出　　处：《Journal of Ocean University of China》2010年第1期1-10,共10页中国海洋大学学报（英文版）

基　　金：supported by the National Basic Research Program of China (973 Program) (Grant No.2005CB422304);the Ocean University of China Scientific Research Start-up Funds Project for Introduced Talents

摘　　要：The DFI-1 submarine pipeline was investigated using a dual-frequency side-scan sonar and a swath sounder system. More than a hundred scour pits under the pipeline were found, most of which have caused the span of the pipeline to increase and threatened its safety. The maximum allowable free span length （MAFSL） of the pipeline was determined through the limitations re- garding maximum allowable stress under static or quasi-static loads and the onset of Vortex Induced Vibrations （VIV） under different hydrodynamic actions. The results show that the MAFSL under static conditions is 56m. However, the MAFSLs are 30m and 20m under ordinary weather conditions and hurricane-induced currents for the 100-year return period, respectively, to avoid VIV as cal- culated by using the highest safety class factor. It is suggested that spanning pipelines longer than 20 m should be supported. Addi- tionally, eight successive spans which may also threaten the pipeline were proposed. The most hazardous scour pits are along the pipeline section from KP42 to KP51.The DF1-1 submarine pipeline was investigated using a dual-frequency side-scan sonar and a swath sounder system.More than a hundred scour pits under the pipeline were found,most of which have caused the span of the pipeline to increase and threatened its safety.The maximum allowable free span length (MAFSL) of the pipeline was determined through the limitations regarding maximum allowable stress under static or quasi-static loads and the onset of Vortex Induced Vibrations (VIV) under different hydrodynamic actions.The results show that the MAFSL under static conditions is 56 m.However,the MAFSLs are 30 m and 20 m under ordinary weather conditions and hurricane-induced currents for the 100-year return period,respectively,to avoid VIV as calculated by using the highest safety class factor.It is suggested that spanning pipelines longer than 20 m should be supported.Additionally,eight successive spans which may also threaten the pipeline were proposed.The most hazardous scour pits are along the pipeline section from KP42 to KP51.

关 键 词：submarine pipeline SCOUR SPAN safety assessment Vortex Induced Vibrations （VIV） maximum allowable span length 

分 类 号：U448.27[建筑科学—桥梁与隧道工程] TE973.92[交通运输工程—道路与铁道工程]