【摘 要】
:
The off-bottom tow is an important method to lay pipeline for offshore oil and gas transportation in shallow water area. During the off-bottom towing operation,
【机 构】
:
Institute of Structural Engineering
【基金项目】
:
国家高技术研究发展计划(863计划)
论文部分内容阅读
The off-bottom tow is an important method to lay pipeline for offshore oil and gas transportation in shallow water area. During the off-bottom towing operation, the actions such as sea current resistance, friction force of seabed, pontoon buoyancy, and tow force of tugboat can cause large deformation and fatigue damage to the pipeline. In order to keep the pipeline in safety, the lateral and vertical deformations of pipeline must be controlled within an appropriate range. Theoretical study is carried out in the paper on the environmental forces acting on pipeline, pontoons and chains, and the confirmation of tow parameters including tow forces of tugboat, number of pontoons and length of chains. Then the pipeline in the off-bottom towing process may be simplified into a continuous beam with elastic supports under the concentrated and distributed forces. A finite element method is applied to achieve numerical solutions describing the distributions of deformation and stress along the pipeline. The results show that the lateral shape of the pipeline is like an arc with the maximal deformation appearing at the middle of the pipeline. The distributions of stress are similar between two arbitrary pontoons. Moreover, both deformation and stress have the inverse relation with the tow forces of tugboat.
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