深海采矿船升沉对大偏移扬矿管动态特性的影响研究

Many countries are engaging actively in the research of deep-sea resources mining because of the rich resource reserves in deep-sea seafloor and the dwindling of land resources. A large number of studies have been carried out on the large nonlinear migration law of marine mining riser under marine environmental loads. In the first place,this project mainly aimed at the multi metal nodule resource exploitation system in 6000 meters sea floor , used nonlinear large deformation theory, analytical mechanics, vibration theory and fluid mechanics theory to study the influence of the heave motion of the mining ship on the vibration of the large offset mining pipe. Secondly ,by means of taking into account the external role of waves, currents, mining vessels and other external pipelines, as well as the different pipeline pipeline shape, materials, structure and ancillary equipment. Using Kirchhoff stress tensor and Green-Lagrange strain tensor and virtual work principle. The mechanical model and mathematical model of the comprehensive lifting pipe are established, and the geometric nonlinear finite element model is established by using the incremental method. Finally, this paper studies the motion response of the mining ship platform under wind, wave, flow and other environmental loads, and the coupling response between the mining pipe and the mining ship. The dynamic response of the lifting pipe under the heave motion of the mining ship is obtained, which provides a theoretical basis for the research and development of the deep sea mining system, and ensures the safe and reliable operation of the mining system.

陆地资源日益减少，深海资源极为丰富，世界各国都在积极从事深海资源开采技术研究工作。深海采矿扬矿管在海洋环境载荷作用下非线性大偏移规律已经进行了大量研究，本项目主要针对6000米海底多金属结核资源开采系统，利用非线性大变形理论、分析力学、振动理论、流体力学理论等研究海面采矿船升沉运动对大偏移扬矿管的振动影响。应用Kirchhoff 应力张量和Green-Lagrange应变张量及虚功原理，综合考虑海浪、海流、采矿船升沉等外部作用，以及扬矿管的不同管线形态、材料、结构及其附属设备，建立综合扬矿管力学模型和数学模型；运用增量方法建立大偏移扬矿管几何非线性有限元模型；研究采矿船平台在风、浪、流等环境载荷作用下的运动响应，以及杨矿管与采矿船之间的运动耦合响应。得到扬矿管在采矿船升沉运动作用下的动态响应，为深海采矿系统的研究开发提供理论依据，确保采矿系统安全可靠运行。

陆地资源日益减少，深海资源极为丰富，深海矿产资源的开采技术正成为目前各国研究的热点。本项目针对6000米海底多金属结核开采系统，基于扬矿管几何非线性构形，利用有限元法、振动理论、流体力学等研究了采矿船升沉运动时大偏移扬矿管的动态行为和船-管之间的耦合响应。.提出了一种基于弯矩平衡思想和弹性力学小变形理论获取扬矿管几何非线性构形的解析求解方法，通过ABAQUS软件验证了方法的有效性。利用该方法分析了不同因素下管道的偏移和静力学特性，结果表明，横向偏移随逆流拖航速度的增大而增大，随矿仓质量的增大而减小，拖航速度越大弯曲应力也越大，而矿仓质量对弯曲应力的影响较小；轴向应力在管道阶梯处发生突变，随逆流拖航速度的增加其值略有减小；最大弯矩出现在距海面约20m处，随水深的增加弯矩迅速减小。.分析了扬矿管的纵向振动和横向振动特性。基于几何非线性理论建立了扬矿管有限元动力学方程，推导出单元刚度、质量矩阵，同时分析了扬矿管梁单元的单元阻尼矩阵和外界载荷矩阵，通过Wilson-θ法对扬矿管系统的动力学响应进行求解。结果表明，管道横向振幅从上到下先减小后增加，最大振动出现在扬矿管顶端，而纵向振幅从上到下逐渐增加，最大振动出现在扬矿管末端；矿仓质量的增加可降低管道横向振动幅值，增大纵向振动幅值，而拖航速度的增加会增大管道横向振动幅值，降低纵向振动幅值。.研究了采矿船与扬矿管之间的运动耦合响应。利用AQWA和OrcaFlex软件建立了船-管耦合模型，模拟了不同海态和波向下系统的耦合动态行为。基于傅汝德相等和斯托哈数相等的相似准则建立了试验模型，开展相关船-管耦合实验，验证了模型仿真结果。结果表明，扬矿管可以抑制采矿船的运动，抑制效果与波浪方向和海况等级相关，180°波向4级海况时抑制效果最为明显，升沉幅值降低了31.11%；船管耦合效应可以导致扬矿管的不规则振荡，90°波向时，顶部张力的稳态值、耦合值的差异为8.6%。