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在陆地矿产资源日渐枯竭的今天,深海矿产资源已成为全球各个国家争相开采与利用的焦点,深海采矿车是实现深海矿产资源开采的重要装备。海底稀软底质是一种承载力与抗剪强度极低的特殊底质,在采矿作业中,深海稀软底质的物理力学特性直接影响采矿车行走的稳定性。文章选取Burger’s接触模型作为深海稀软底质的本构模型,对某海域海底稀软原状土开展室内三轴试验,通过PFC3D颗粒流数值模拟实验对比实际三轴试验,对稀软底质的Burger’s蠕变模型进行参数标定,同时依据标定结果改变相应参数,针对5种不同底质条件的工况,建立海底采矿车的数字仿真模型,模拟各工况下采矿车在不同行驶速度时的下陷深度。结果显示,下陷深度会随行驶速度呈非线性变化,在一定范围内随着行驶速度的增大而减少并逐渐趋于稳定。同时结果还表明,该区域海底稀软底质具有更高的黏粒含量（38.1%～48.4%）、含水率（88.13%～137.79%）和压缩性（压缩系数：1.86～3.73 MPa-1,压缩模量：1.26～2.13 MPa）,具有更低的密度（1.3～1.5 g/cm3）和强度特性（贯入阻力：0.19～1.32 N,黏聚力：3.7～6.9 k... 相似文献
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随着陆地金属资源的日益枯竭,深海矿产资源已经成为各国的重要战略目标。在深海采矿过程中,海底锰结核的形状除了圆球状,还有长条状等,颗粒形状对固液两相流管道输送特性具有很大影响。基于固液两相流垂直管道提升输送试验系统,探究不同工况下长条状颗粒在垂直上升流中最小输送速度的变化规律及特性,并得到了长条状群体颗粒最小输送速度计算公式。结果表明:长条状颗粒在垂直管道中上升过程中,颗粒中心轴与输送方向趋向于垂直,使颗粒在管道截面的投影面积最大化;长条状单颗粒的最小输送速度随着颗粒长径比增大而减小;在不同长径比工况下,随着管段颗粒平均浓度减小,长条状群体颗粒的最小输送速度均增大,且随着长径比增大,群最小输送速度减小。 相似文献
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目前公认的深海采矿系统是利用管道水力将深海底矿石提升到海面采矿船上。由于受海底破碎条件和废水排放环境要求,输送的深海矿石粒径较粗。粗颗粒具有极易沉积的特点,输送参数也较难确定。通过自行设计的管道水力输送模拟系统,研究了不同浓度、粒径、速度条件下粗颗粒在水平管道中的运动状态及阻力损失的变化规律。研究结果表明:(1)随固液两相流流速的增大,水力坡度呈现规律性变化,且阻力损失的变化规律与粗颗粒运动状态存在一定的关系;(2)通过引入管道附加损失与福氏数,建立了颗粒运动状态与阻力损失之间的定量关系,提出了粗颗粒在水平管道水力输送条件下流态分区的判定标准;(3)分析了管道附加损失的影响因素,提出了管道附加损失的计算公式。研究结果为粗颗粒管道水力输送系统参数设计提供依据。 相似文献
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热液羽状流是海底热液活动的重要标志，海底多金属硫化物是热液活动的产物。现阶段洋中脊多金属硫化物勘探工作的第一步是开展热液羽状流的近底探测；综合各类异常信息，实现从发现热液活动喷口到发现矿床的突破。本文以热液羽状流为研究对象，从羽状流的近底探测、扩散机制和分布特征3个方面，概述了最新的研究进展和有待完善的方面，阐述了羽状流在洋中脊多金属硫化物找矿中的指示作用，最后总结性地指出时空连续性、参数多元化将是热液探测的发展趋势，有助于提升对热液羽状流分布特征的认识，将为热液区分布模式的研究提供更加精细的探测资料。 相似文献
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开展海底滑坡运动特性研究是深水陆坡区滑坡地质灾害认识与防治的基础,建立了基于非牛顿流体欧拉-欧拉两相流理论的小尺度海底滑坡数值模型。在与实验数据和BING程序结果对比验证的基础上,模拟分析海底滑坡的一般运动规律及特性,并同无水条件下的滑坡模拟结果进行了对比。结果表明:环境水的存在可引发"滑水"现象,延长滑坡运动时间,增加运动距离,但端部最大峰值速度相对无水条件时较小;滑坡体物质组成、地形坡度、初始速度、初始厚度等因素,对最终的运动距离有较大的影响;滑坡体在运动过程中因扰动、混水而导致的屈服强度和粘滞系数的不断降低是海底滑坡长距离运动的主要原因。 相似文献
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针对具有颗粒粒级跨度大且粒径大特点的固液两相流系统,如深海采矿系统等,开发新型粗颗粒—均质浆体计算模型,该模型采用欧拉—拉格朗日计算法,大粒径颗粒视为固相粗颗粒,其余视为细颗粒与海水组成液相均质浆体。固—液相间滑移速度v_(slip)作为粗细颗粒划分标准,通过联立颗粒雷诺数Re_p,液相对颗粒绕流阻力系数C_d,颗粒粒径d_p等参数,得到滑移速度v_(slip)与颗粒粒径d_p的相关函数,获得粗细颗粒的划分粒径,进而得到两相流控制方程。利用CFD软件,使用该方法对粗颗粒固—液两相流垂直管提升系统进行仿真计算,并将所获得的仿真结果与已发表成果进行对比,发现数据较为吻合,从一定程度上验证了该计算模型的准确性。 相似文献
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深海采矿船是未来人类获取深海矿产资源的重要装备，研究其水动力特性具有重要意义。月池和输运管是影响深海采矿船水动力特性的重要因素。以世界上第一艘超深水采矿船“鹦鹉螺新纪元”号为研究对象，基于三维势流理论，分析月池尺寸、输运管长度及内径对采矿船水运动特性的影响。结果表明：月池开口会使采矿船垂荡、纵荡和纵摇运动出现共振峰，峰值随着开口尺寸的增加而增大，其中垂荡运动峰值可增加将近2倍；输运管的存在会明显改变采矿船横摇运动固有周期，增大垂荡运动峰值，降低横摇运动峰值，对横荡和纵荡运动的影响亦较大，当输运管长度为 5 000 m，内径为0.480 5 m时，横荡和纵荡响应峰值能够达到无输运管时的3倍以上。通过探究月池开孔和输运管不同参数对采矿船运动的影响，为深海采矿船月池和输运管设计提供一定的借鉴和参考。 相似文献
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一种新型振荡流实验装置及其应用 总被引：1，自引：0，他引：1
本文介绍了由大连理工大学土木系海洋工程研究室研制的一种新型振荡流实验装置,它不但可以做振荡流实验,还可以做恒定流实验;在振荡流条件下,它可以达到比较大的KC数(=U_mT/D).本文首次运用这套实验装置,对深海中接近海底的水平管在振荡流作用下的受力进行了研究,分析了距海底不同高度的水平管力系数C_(FHrmS)和C_L值,得出了一些有意义的结论,并给出了力系数随参数KC和ξ值(=e/D)的变化曲线。 相似文献
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《海洋技术学报》2023,(3)
深海中蕴藏着丰富的矿产资源，深海采矿船是深海采矿的重要装备，通过动力定位系统控制采矿船的海上位置，动力定位系统由若干推进器组成。采矿船在海上受到风浪流作用，推进器一旦失效极易发生采矿船运动失控等安全事故，本文研究推进器不同失效方式下动力定位性能，分析推进器不同失效方式动力定位功能的损失。根据势流理论计算波浪载荷，数值模拟深海采矿船不同位置的单个推进器失效和多个推进器失效方式下的时域运动响应，对比各种失效方式对深海采矿船纵荡、横荡、艏摇三个自由度运动的影响，分析各种失效方式对剩余推进器推力的影响。研究结果表明：采矿船空载90°浪向，推进器不同失效模式对于纵荡运动影响远小于对横荡和艏摇运动影响，船艉单推进器失效对于纵荡和艏摇动力定位的影响大于两个推进器失效影响；对于采矿船多自由度运动动力定位两个推进器失效大于单推进器失效影响；一侧两个推进器或两侧推进器同时失效，对动力定位的影响相同，对于横荡运动的影响最大。本文揭示了深海采矿船推进器失效对于采矿船运动的影响程度和机理，对于深海采矿船的安全作业具有指导意义。 相似文献
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A computational fluid dynamics (CFD) model was developed to simulate the turbulent flow and species transport of deep-sea high temperature hydrothermal plumes. The model solves numerically the density weighted unsteady Reynolds-averaged Navier–Stokes equations and energy equation and the species transport equation. Turbulent entrainment and mixing is modeled by a k–ε turbulence closure model. The CFD model explicitly considers realistic vent chimney geometry, vent exit fluid temperature and velocity, and background stratification. The model uses field measurements as model inputs and has been validated by field data. These measurements and data, including vent temperature and plume physical structure, were made in the ABE hydrothermal field of the Eastern Lau Spreading Center. A parametric sensitivity study based on this CFD model was conducted to determine the relative importance of vent exit velocity, background stratification, and chimney height on the mixing of vent fluid and seawater. The CFD model was also used to derive several important scalings that are relevant to understanding plume impact on the ocean. These scalings include maximum plume rise height, neutrally buoyant plume height, maximum plume induced turbulent diffusivity, and total plume vertically transported water mass flux. These scaling relationships can be used for constructing simplified 1-dimensional models of geochemistry and microbial activity in hydrothermal plumes. Simulation results show that the classical entrainment assumptions, typically invoked to describe hydrothermal plume transport, only apply up to the vertical level of ~0.6 times the maximum plume rise height. Below that level, the entrainment coefficient remains relatively constant (~0.15). Above that level, the plume flow consists of a pronounced lateral spreading flow, two branches of inward flow immediately above and below the lateral spreading, and recirculation flanking the plume cap region. Both turbulent kinetic energy and turbulence dissipation rate reach their maximum near the vent; however, turbulent viscosity attains its maximum near the plume top, indicating strong turbulent mixing in that region. The parametric study shows that near vent physical conditions, including chimney height and fluid exit velocity, influence plume mixing from the vent orifice to a distance of ~10 times the vent orifice diameter. Thus, physical parameters place a strong kinetic constraint on the chemical reactions occurring in the initial particle-forming zone of hydrothermal plumes. 相似文献
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Derek V. Ellis 《Marine Georesources & Geotechnology》2001,19(1):51-63
This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested. 相似文献
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Derek V. Ellis 《Marine Georesources & Geotechnology》2013,31(1):51-63
Abstract This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be site-specific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of “marine snow” (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested. 相似文献
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海底集矿作为深海矿产资源开发的核心技术之一,直接影响到矿石采集效率和海底沉积物受扰动程度。基于康达效应的水力集矿装置因具有结构简单、可靠性高及对海床扰动小等优点,受到广泛关注。针对基于康达效应的水力集矿头模型进行3种类型的试验研究：1)利用粒子图像测速(PIV)技术测得集矿流场速度分布,试验发现流体质点在靠近凸曲面壁处流速和沿法线速度梯度较大,而远离凸曲面壁处则相反;2)通过高速摄像和图像处理获得球形矿粒运动轨迹和速度,试验发现了不同射流流速下5种典型矿粒运动形态;3)分析了射流流量对矿粒采集率的影响,试验得到了颗粒采集率关于射流流量的变化曲线,并根据变化特征划分为增长区、缓变区和跃升区。研究可为新式集矿装置的优化设计与性能分析提供参考。 相似文献
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文章旨在确定深海多金属结核的物理特性，并分析其对采输过程的影响，以指导工程应用。总结了深海多金属结核开采的最新研究进展，通过对数据进行统计整理、回归分析，确定了结核形成机理及主要成分、在海底的分布特性、结核形态及构造、结核尺寸与重量关系、含水量、密度、孔隙特性及结核强度等关键物理特性。研究表明：结核形状多样，质松多孔隙，含水率高，近似均匀分布在海床上或浅泥层中。颗粒质量和尺寸联合概率分布具有长右尾特性，需使用更广义的联合概率密度函数copula才能准确建模。结核抗拉强度随结核直径增大按对数函数递减。此外，深海高压环境下结核的开采需更多能耗，且结核表现出更高的延性。结合固液两相流分析和颗粒沉降理论，分析了结核形状、尺寸、密度等主要参数对水力举升过程的影响，确定了颗粒破碎的主要方式和规律，总结了不同粒径级配输运造成堵塞的可能原因。 相似文献
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Rates, concentrations, and composition of mining discharge and the size and structure of the ensuing surface plumes were examined during North Pacific tests of scaled manganese nodule mining systems. Discharge was composed principally of bottom water and pelagic silts and clays, although nodule fragments with diameters less than 1 mm were also discharged at widely varying rates. Average flow rates of the discharge varied from 95 to 160 litres/s, with the solid fraction varying from 550 to approximately 2000g/s. The plume, as determined by particulate concentrations in excess of ambient oceanic conditions, extended approximately 5 km from the mining ship and had a width of about 1 km. Fe and Mn signatures allowed detection of the plume nearly 35 km from the source. The plume provided evidence of settling more rapidly than expected of silt and clay-size particles: a mean settling velocity of 6 × 10?2 cm/s for the particulates in the plume and a mixed layer vertical turbulent eddy diffusivity of 1 × 10?2m2/s have been inferred from the data. Field and laboratory data together suggest that the rapid settling was due to flocculation of the discharge particulates. 相似文献
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海底矿石在软管中的水力输送是深海采矿的重要过程。采用计算流体动力学—离散元耦合的计算方法（CFD-DEM），对矿石颗粒在软管中的输送进行数值模拟，重点关注矿石颗粒的运动、分布规律以及管壁受到的颗粒作用力，分析输送速度和输送浓度（入射颗粒的体积分数）对输送过程的影响规律，探索管道中易发生堵塞、易受颗粒磨损的区域。结果表明，软管中颗粒的动力学特性与管道倾角、输送速度和输送浓度有关。颗粒主要沿管道截面底部推移，倾角较大的上升段出现处于悬移状态的颗粒；管道横截面内颗粒运动速度从上至下递减，截面中心处颗粒的速度接近输送速度。输送过程中颗粒的局部浓度（该区域颗粒与固液两相流的体积比）始终大于输送浓度，局部平均速度始终小于输送速度。上升段颗粒体积分数大于下降段，颗粒速度小于下降段。管道拱顶和谷底位置管壁所受颗粒作用力最明显，管壁最可能受颗粒磨损。 相似文献
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A. B. Valsangkar 《Marine Georesources & Geotechnology》2013,31(4):357-371
Benthic disturbance due to future deep-sea polymetallic nodule mining would involve expensive sediment plume generation and resedimentation on the sea floor. In order to evaluate the effects of resedimentation on benthic environment, the Indian Deep-sea Environment Experiment (INDEX) was conducted in 1997, and pre-, and post-disturbance studies on grain size were carried out. The initial increase in clay content after the experiment, continued to increase further as measured in the first monitoring phase samples, 44 months later. Increase in clay-sized particles during monitoring-l (M-l) was highest within the simulated (disturbed) zone and to the north of it, which is attributed to the combined effects of disaggregation, abrasion, and powderization of sediments during transportation. Due to this fractionation (breaking up), the particles appear to have remained in suspension over a prolonged period of time after they were discharged in the water column 5 m above the seabed during INDEX. The travel effects of INDEX plume appears to be localized and confined within and around the disturbed zone (DZ) as resettlement of fine particles from the benthic plume was traced up to 2 km south and 12 to 18 km north of the DZ. The evidence does not suggest the existence of strong currents and benthic storms in the CIB 相似文献
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This paper presents a computational model of simulating a deep-sea hydrothermal plume based on a Lagrangian particle random walk algorithm. This model achieves the efficient process to calculate a numerical plume developed in a fluid-advected environment with the characteristics such as significant filament intermittency and significant plume meander due to flow variation with both time and location. Especially, this model addresses both non-buoyant and buoyant features of a deep-sea hydrothermal plume in three dimensions, which significantly challenge a strategy for tracing the deep-sea hydrothermal plume and localizing its source. This paper also systematically discusses stochastic initial and boundary conditions that are critical to generate a proper numerical plume. The developed model is a powerful tool to evaluate and optimize strategies for the tracking of a deep-sea hydrothermal plume via an autonomous underwater vehicle (AUV). 相似文献