Abstract

Internal solitary waves bring great challenges to the safety of deep-sea mining pipeline deployment operations. The three-dimensional finite element model of deep-sea mining pipeline system under the action of internal solitary waves is established and solved. The shape, tension, stress, upper rotation, offset, and transient response of the pipe string during the deployment process of the deep-sea mining system under the internal solitary wave environment are analysed, and dangerous stages and risk factors are obtained. The envelopes of deployment operations under different internal solitary waves are calculated, and the technical measures to enlarge the operation envelope are discussed. The results show that the upper rotation and offset at moon pool position are more easily affected by internal wave energy relative to stress and tension, and they are the main factors affecting the safety of operation. The stage that the mining vehicle passes through the high-velocity zone of internal solitary waves is the high-risk stage. The operation envelope is the smallest when the IW-OC direction angle is 0°, and is the largest when the angle is 180°. Strengthening the upper restraint has limited effect on improving the operation envelope, in contrast, turning on the propellers of mining vehicle to resist the internal wave when necessary can effectively expand the operation envelope.

摘要

内部孤立波给深海采矿管道部署作业的安全带来了巨大挑战。建立并求解了内部孤立波作用下的深海采矿管道系统三维有限元模型。分析了深海采矿系统在内部孤立波浪环境下展开过程中管柱的形状、张力、应力、上部旋转、偏移和瞬态响应，得出了危险阶段和危险因素。计算了不同内部孤立波下的部署操作包络线，讨论了扩大操作包络线的技术措施。结果表明，相对于应力和张力，月池位置的上层旋转和偏移更容易受到内波能量的影响，是影响操作安全的主要因素。矿车通过内部孤立波高速区的阶段为高风险阶段。IW-OC方向角为0°时操作包络线最小，角度为180°时最大。加强上部约束对改善作业包络线的作用有限，而在必要时开启矿车螺旋桨抵抗内波可有效扩大作业包络线。