【作者】 王志；

【导师】 饶秋华；

【作者基本信息】 中南大学 ， 工程力学， 2010， 博士

【摘要】 本文以我国深海采矿1000m海试系统为研究对象,采用理论分析、数值计算与试验研究相结合的方法,综合考虑管道系统承受的各种复杂载荷(如重力、浮力、海流、海浪、内部流作用等)以及集矿机、采矿船运动的影响,开展扬矿管道工作特性(包括运动、力学性能及输送等)的流固耦合分析与综合评价研究,探讨集矿机与采矿船行走工况、浮力块布置方式、流体输送参数、材料性能等优选方案,为深海采矿管道系统的设计与研发提供重要依据。本文取得的主要研究成果如下：(1)基于深海采矿扬矿硬管受力简化模型,采用Matlab语言自行编制了二维无网格局部Petrov-Galerkin法程序,计算并分析了硬管在海流阻力作用下的偏移特性。结果表明：硬管最大偏移量发生在靠近中间仓一端,最大拉应力发生在靠近采矿船一端；硬管最大偏移量随逆流拖航速度的增加而增加,随顺流拖航速度的增加而先减后增。(2)采用三维非线性有限元法,通过MSC.MARC/MENTAT软件建立了布放过程中扬矿软管初始空间构形的静态分析模型,计算并分析了软管初始空间构形特性及其多种因素(如浮力块布置方案、海水阻力、支座形式、软管弹性模量等)的影响规律。结果表明：浮力块布置方案直接影响着软管拱顶高度和软管能否全部漂浮于海水中。海水阻力和软管弹性模量对软管初始空间构形影响较小。为确保软管安全及输送效率,建议浮力布置范围限定在L／2-3L／4(均布)、L／3-2L／3(单个浮力块集中作用)或L／4-3L／4(两个浮力块集中作用)；浮力块浮力的取值范围为0.9G≤F≤1.5G(G为软管净浮重)；建议选用对称支座形式(两端固支或铰支)。(3)基于流固耦合理论,通过MSC.MARC/MENTAT软件建立了软管与内部流三维流固耦合有限元模型,计算并分析了复杂深海环境下扬矿软管运动与力学特性、输送及其多种因素(如内部流提升速度、屈服应力与粘性系数、软管弹性模量、集矿机行走工况等)的影响规律。为保证深海开采的连续稳定和开采效率,建议内部流提升速度控制在合适的范围内(如2.5-4m／s)；采取适当延长集矿机内矿物破碎和脱泥时间、降低矿物粒径及内部流浓度、减少泥沙含量等措施；内部流浓度控制在合适范围内(如10%-25%)；尽可能采用弹性模量适中的软管材料；当集矿机圆形行走和方形行走时,选取集矿机转弯或位移变号时的软管应力作为软管接头强度设计参数；集矿机行走速度应控制在0.2-0.4m/s。(4)针对传统主成分分析法存在的不能反映待评价方案与最优方案相似程度的问题,提出了一种基于指标优化原则进行数据矩阵标准化的改进主成分分析法,应用于深海采矿软管工作特性的综合评价,并与模糊层次法评价结果进行对比。结果表明：两种方法评价结果基本一致,即具有S形和马鞍形空间构形的软管工作特性评价值较高,可作为软管设计的优选方案。改进的主成分分析方法不依赖于主观因素,能够获得真实可靠的评价结果,特别适用于深海采矿系统多指标工作特性优劣的综合评价。(5)基于相似理论,自行设计了软管空间构形与输送的试验装置,开展了在不同浮力块布置方案下的软管空间构形、在不同的软管初始空间构形下的软管输送的试验研究,获得了软管空间构形的优选方案(如S形、马鞍形等),实测结果与有限元计算结果、综合评价结果吻合较好。(6)综合考虑内部内部流、外部海流与海浪以及集矿机、采矿船运动状态,通过MSC.MARC/MENTAT软件建立了深海采矿扬矿管道整体联动的三维流固耦合有限元模型,计算并分析了管道系统的运动、力学特性及其多种因素(如拖航速度、海浪周期、中间仓结核质量等)的影响规律。为提高采矿系统的安全可靠性和开采效率,建议拖航速度和结核质量控制在合适的范围内(分别为0.3-0.5m/s、2000-4000kg),且尽量避免在海浪振动周期太小时逆流拖航作业。更多还原

【Abstract】 Working characteristics of pipelines in a 1000m deep-ocean mining system was studied theoretically, numerically and experimentally, including space configuration, mechanical properties and transportation performance. Optimal layout of buoyancy blocks imposed on the flexible hose and walking path of the mining machine was proposed based on comprehensive evaluation of working characteristics of the lifting pipeline, which can provide a scientific basis for the design of the deep-ocean mining system.Main research results are as follows:(1) Based on simplified mechanical model of the lifting pipe in deep-ocean mining system, a new program of meshless local Petrov-Galerkin method in Matlab language was designed to calculate offset characteristic of the lifting pipe subjected to current resistance. Numerical results show that the maximum offset of the lifting pipe occurs near the end of buffer and the maximum tensile stress of the lifting pipe occurs near the end of the mining ship. The maximum offset of the lifting pipe increases with the increase of the towing speed in countercurrent flow. It decreases first and then increases as the towing speed increase in concurrent flow.(2) Three-dimensional nonlinear finite element model of the initial space configurations of the flexible hose was established to analyze effects of the layout of buoyancy blocks, current resistance, bearing form and elastic modulus on the characteristics of initial space configuration of the flexible hose in launching process. Numerical results show that the layout of buoyancy blocks greatly influence the height of space configuration and complete floating of the flexible hose in deep ocean. In order to ensure safety and transportation efficiency of the flexible hose, the buoyancy block should be imposed in the range of L/2-3L/4 for uniform distribution, L/3-2L/3 for concentrated distribution of single buoyancy block and L/4-3L/4 for concentrated distribution of double buoyancy blocks. The total buoyancy force of the buoyancy block must be restricted within into the range of 0.9G≦F≦1.5G (where G is net buoyancy force). Fixed or hinged constraints should be added at the two ends of the flexible hose. Current resistance and bearing form have little effect on the characteristics of initial space configuration of the flexible hose.(3) Based on fluid-solid coupling theory, three-dimensional nonlinear finite element model of fluid-solid coupling was established to investigate space configuration, mechanical properties and transportation performance of the flexible hose as well as influencing factors, including lifting velocity, yielding stress and viscosity coefficient of the mineral fluid, elastic modulus of the flexible hose and walking path and velocity of the mining machine. In order to improve stability and efficiency of the mining operation, the lifting velocity of the mineral fluid must be limited to a suitable ranges (e.g.2.5-4 m/s). Effective measures should be taken such as extension of the time of mineral crushing and desliming and decrease of the particle size, mineral concentration and sediment content). Concentration of the mineral fluid must be limited within 10%-25%. Suitable materials of moderate elastic modulus should be used for the flexible hose. Maximum stress of the flexible hose occurs when the mining machine turns in circle walking-path or changes the sign of walking displacement in square walking-path, which is key parameter for strength design of joints. Walking velocity of the mining machine must be controlled within 0.2-0.4m/s.(4) In view of difficult reflection of the similarity between the evaluated scheme and the optimal solution in traditional principal component analysis, an improved method of principal component analysis based on index optimization principle of data matrix standardization is proposed for comprehensive evaluation of working characteristics of the flexible hose, which was compared with the method of fuzzy hierarchy analysis. Similar evaluation results are obtained by using the two methods, i.e., space configurations of S-shape and saddle shape have higher evaluation indices and can be used for optimal design of the flexible hose. The improved method of principal component analysis independent of subjective factors can give real and reliable evaluation results, which is especially suitable for comprehensive evaluation of multiple-index working characteristics of the deep-ocean mining system.(5) Based on similarity theory, a test device for space configuration and transportation performance of the flexible hose is designed to experimentally study effects of the distribution of buoyancy blocks and buoyancy force on the initial space configuration of the flexible hose and effects of different initial space configurations on the transportation performance of the flexible hose for the first time. Test results of optimal space configurations are in good agreement with the numerical results of comprehensive evaluation.(6) By comprehensive consideration of the interaction of inner mineral fluid, external current and wave and the motion of mining machine and mining ship, three-dimensional nonlinear finite element model of fluid-solid coupling was established to analyze dynamical responses of the deep-ocean mining system influenced by towing velocity of the mining ship and the mining machine, wave period and nodule mass stored in the buffer. Numerical results show that for safety and efficiency of the mining operation, the velocity of the mining machine and the nodule mass should be limited within appropriate ranges (about 0.3-0.5m/s and 2000-4000kg) and the countercurrent mining operation must be avoided in the case of smaller wave period.更多还原