Research on Pressure Tight Sampling Technique of Deep-Sea Shallow Sediment—A New Approach to Gas Hydrate Investigation

Analyzed and calculated are pressure changes and body deformation of the sample inside of the corer in the process of sampling of deep-sea shallow sediment with a non-piston corer for gas hydrate investigation, Two conclusions are drawn： （1） the stress increments associated with the corer through the sampling process do not affect the stabilization of the gas hydrate; （2） the body deformation of the sample is serious and the ＂incremental filling ratio＂ （IFR） is less than unit, For taking samples with in-situ pressure and structure, combining with the design theories of the pressure tight corer, we have designed a kind of piston corer, named the gas hydrate pressure tight piston corer, Several tests on the sea have been conducted. Test results indicate that the piston corer has a good ability of taking sediment samples on the seafloor and maintaining their original in-situ pressure, meeting the requirement of exploration of gas hydrate in deep-sea shallow sediment layers.

Distinct influence of trimethylamine N-oxide and high hydrostatic pressure on community structure and culturable deep-sea bacteria

Trimethylamine N-oxide(TMAO)is one of the most important nutrients for bacteria in the deep-sea environment and is capable of improving pressure tolerance of certain bacterial strains.To assess the impact of TMAO on marine microorganisms,especially those dwelling in the deep-sea environment,we analyzed the bacterial community structure of deep-sea sediments after incubated under different conditions.Enrichments at 50 MPa and 0.1 MPa revealed that TMAO imposed a greater influence on bacterial diversity and community composition at atmospheric pressure condition than that under high hydrostatic pressure(HHP).We found that pressure was the primary factor that determines the bacterial community.Meanwhile,in total,238 bacterial strains were isolated from the enrichments,including 112 strains a ffiliated to 16 genera of 4 phyla from the Yap Trench and 126 strains a ffiliated to 11 genera of 2 phyla from the Mariana Trench.Treatment of HHP reduced both abundance and diversity of isolates,while the presence of TMAO mainly af fected the diversity of isolates obtained.In addition,certain genera were isolated only when TMAO was supplemented.Taken together,we demonstrated that pressure primarily defines the bacterial community and culturable bacterial isolates.Furthermore,we showed for the first time that TMAO had distinct influences on bacterial community depending on the pressure condition.The results enriched the understanding of the significance of TMAO in bacterial adaptation to the deep-sea environment.

Nonlinear Contact Between Inner Walls of Deep Sea Pipelines in Buckling Process

In order to study buckling propagation mechanism in deep sea pipelines, the contact between pipeline's inner walls in buckling process was studied. A two-dimensional ring model was used to represent the pipeline and a nonlinear spring model was adopted to simulate the contact between inner walls. Based on the elastoplastic constitutive relationship and the principle of virtual work theory, the coupling effect of pipeline's nonlinear large deformation and wall contact was included in the theoretical analysis with the aid of MATLAB, and the application scope of the theoretical model was also discussed. The calculated results show that during the loading process, the change in external pressure is closely related to the distribution of section stress, and once the walls are contacting each other, the external pressure increases and then remains stable after it reaches a specific value. Without fracture, the pipeline section will stop showing deformation. The results of theoretical calculations agree well with those of numerical simulations. Finally, in order to ensure reliability and accuracy of the theoretical results, the collapse pressure and propagation pressure were both verified by numerical simulations and experiments. Therefore, the theoretical model can be used to analyze pipeline's buckling deformation and contact between pipeline's inner walls, which forms the basis for further research on three-dimensional buckling propagation.

Pressure Tight Piston Corer—A New Approach on Gas Hydrate Investigation

A pressure tight sediment sampling technology, which can be introduced into the modification of the piston corer to accommodate the investigation of gas hydrate, is put forward. In this paper, the three basic rules of the technology are analyzed in detail: specimen transferring rule, seal self-tightening rule and semi-active pressure holding rule. Based on these, the structure of the pressure tight piston corer is put forward and its working principle is analyzed. Finally, a pressure tight sediment sampler, to which the same technology is applied, is researched through experiments. Results show that the sampler based on the above-mentioned theory has a good ability in sampling and in -situ pressure holding.

Study of pressure effects on ocean in-situ detection using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy(LIBS) has attracted extensive attention as a new technique for in-situ marine application. In this work, the influence of deep-sea high pressure environment on LIBS signals was investigated by using a compact LIBS-sea system developed by Ocean University of China for the in-situ chemical analysis of seawater. The results from the field measurements show that the liquid pressure has a significant effect on the LIBS signals. Higher peak intensity and larger line broadening were obtained as the pressure increases. By comparing the variations of the temperature and salinity with the LIBS signals, a weak correlation between them can be observed. Under high pressure conditions, the optimal laser energy was higher than that in air environment. When the laser energy exceeded 17 mJ, the effect of laser energy on the signal intensity weakened. The signal intensity decreases gradually at larger delays. The obtained results verified the feasibility of the LIBS technique for the deep-sea in-situ detection, and we hope this technology can contribute to surveying more deep-sea environments such as the hydrothermal vent regions.

基于组态王与PLC的深水压力模拟测试系统的设计

在深海钻探中,深水仪器在下水前通常需要进行压力模拟测试以验证水密性与耐压性,因此经常用到深水压力模拟测试系统。本文对传统的深水压力模拟测试系统进行了改进,改进后的系统电控部分主要由组态王与PLC组成。PLC作为下位机,通过其内置的A/D模块,配合压力传感器可实现对压力信号的采集,用户可以设置参数与预设程序,通过开关量输出点、接触器等实现试压泵的启停和阀门开关控制;系统支持手动、自动两种工作模式;通过PLC串口配合蓝牙串口透传模块,可实现蓝牙设备端数据显示。组态王作为上位机通过串口以ModbusRTU协议方式与下位机通讯,组态编程开发人机交互界面,实现用户对压力模拟测试全过程的加压、保压、卸荷设置,以及实现监控测试过程、显示压力曲线、显示报表等功能。深水压力模拟测试系统具有人机界面友好、模拟监控形象直观、功能齐全、性能可靠、操作方便、安全及具备可扩展性等优点。

节能型海水液压浮力调节系统

针对现有浮力调节系统能耗高、需配置额外液压源等问题,提出了一种节能型海水液压浮力调节系统,设计了由伺服电机驱动的集成式控制阀组,通过齿轮协同布置、滑动丝杠自锁、螺旋旋向分配等方案实现了电机短时运转控制多个截止阀启闭,完成压载水舱注、排水功能的控制,极大地减少了潜水器能源消耗。此外,通过深海高压环境模拟试验装置,开展浮力调节系统注、排水流量和能耗测试,验证了该浮力调节系统的节能性和有效性,同时满足水下4 km作业深度的要求。

Effect of Deep Sea Pressures on the Corrosion Behavior of X65 Steel in the Artificial Seawater

The corrosion behaviors of X65 steel in the artificial seawater at different hydrostatic pressures are investigated by potentiodynamic polarization measurements, electrochemical impedance spectroscopy measurements and weight loss measurements.The corroded morphologies and the corrosion products are also investigated by scanning electron microscopy, X-ray diffraction analysis and Raman analysis.The results show that the corrosion current increases as the hydrostatic pressure increases.The charge transfer resistance decreases as the hydrostatic pressure increases.The corrosion products are mainly composed of γ-FeOOH and Fe3O4 at the atmospheric pressure, while the main components are γ-FeOOH, Fe3O4, and γ-Fe2O3 at the high pressure.The hydrostatic pressure accelerates the corrosion of X65 steel due to its effect on the chemical and physical properties of corrosion products, including the promoted reduction of γ-FeOOH and the wider and deeper cracks on the corrosion products layer.

Numerical Analysis of Three-Layer Deep Tunnel Composite Structure

To date,with the increasing attention of countries to urban drainage system,more and more regions around the world have begun to build water conveyance tunnels,sewage pressure deep tunnels and so on.However,the sufficient bearing capacity and corrosion resistance of the structure,which can ensure the actual service life and safety of the tunnel,remain to be further improved.Glass Fiber Reinforced Plastics(GFRP)pipe,with light weight,high strength and corrosion resistance,has the potential to be applied to the deep tunnel structure.This paper proposed a new composite structure of deep tunnel lined with GFRP pipe,which consisted of three layers of concrete segment,cement paste and GFRP pipe.A new pipe-soil spring element model was proposed for the pipesoil interaction with gaps.Based on the C3D8R solid model and the Combin39 spring model,the finite element numerical analysis of the internal pressure status and external pressure stability of the structure was carried out.Combined with the checking calculation of the theoretical formula,the reliability of the two finite element models was confirmed.A set of numerical analysis methods for the design and optimization of the three-layer structure was established.The results showed that from the internal GFRP pipe to the outer concrete pipe,the pressure decreased from 0.5 to 0.32 MPa,due to the internal pressure was mainly undertaken by the inner GFRP pipe.The allowable buckling pressure of GFRP pipe under the cover of 5 GPa high modulus cement paste was 2.66 MPa.The application of GFRP pipe not only improves the overall performance of the deep tunnel structure but also improves the construction quality and safety.The three-layer structure built in this work is safe and economical.

深海无人系统大长径比环肋圆柱壳结构设计与试验研究

环肋圆柱壳是深海无人系统广泛采用的一种耐压结构形式,保障其结构安全是系统研制过程中非常重要的一环。针对环肋圆柱壳的结构特征推导了组合结构重量关系式和结构参数简化估算方法,并以一种超长型深海无人系统耐压结构为例,围绕大长径比环肋圆柱壳的结构形式、设计计算、仿真分析、模型验证等开展研究。研究表明提出的大长径比环肋圆柱壳结构设计参数简化估算方法具有较好的适应性。相关计算和分析结果可以为该型深海无人系统结构设计提供技术支撑,也可以为其他类似耐压结构设计提供参考。

深海极端环境下齿轮泵容积效率演变规律研究

大范围变海深环境下液压系统介质黏度变化及关键零部件形变明显,会对齿轮泵容积效率产生影响。为了研究齿轮泵在深海环境下容积效率的变化规律,建立了海深与齿轮泵容积效率的数学模型,通过理论和仿真分析了在不同海深下的齿轮泵的容积效率。结果表明:随着海深的增加,齿轮泵的容积效率逐渐增大。在海深达到11000 m的极限超高压的环境下时,转速以及温度的变化对齿轮泵容积效率影响较陆地更加明显。研究结果为深海齿轮泵优化提供了相关的理论依据,对水下液压元件和液压系统的设计具有一定的参考意义。

深海载人装备耐压结构用钛合金应用现状与展望

耐压结构材料是支撑海洋装备“下得去、上得来”的基础,钛合金以其质量轻、强度高、耐腐蚀的特点而成为深海载人装备耐压结构的优选材料,具有良好应用前景。该文简述了潜艇、深潜器、深海工作站和水下实验室等典型深海载人装备及其耐压结构材料的发展历程和研究进展,介绍了我国的钛工业发展现状、海洋工程用钛合金材料体系、钛合金耐压结构加工制造技术以及设计与试验研究等方面的研究基础,并结合大型深海装备钛合金结构的技术特点分析了耐压结构用钛合金的关键科学技术问题和应用需求,为深海载人装备耐压结构用钛合金的未来发展提供参考。

数据驱动的载人舱球壳下潜过程推演与异常诊断

针对大深度载人舱球壳下潜过程难以推演等问题,本文提出一种数据驱动的下潜过程推演与异常诊断算法。首先,对大深度载人舱球壳结构及历史下潜数据进行分析。其次,将下潜深度作为输入,关键热点应力作为输出,利用长短时记忆神经网络(long short-term memory network,LSTM)构建下潜过程推演模型,并对推演结果进行分析。与DNN模型和BP模型进行对比,推演误差分别降低35.89%和68.30%。最后,基于LSTM模型,提出一种数据异常诊断算法,该算法可对传感器出现故障时的异常数据进行及时诊断与修正。

带球封头的钛合金耐压结构深海碰撞动屈曲研究

钛合金深海装备在水下作业时可能会与海山、礁石等海底固定物发生碰撞,这种在高应力状态下发生的冲击碰撞可能会对钛合金结构稳定性造成很大的影响。目前,学术界对于这种在双重载荷环境下发生的结构稳定性问题并没有太多的研究,也没有可供参考的经验公式。在钛合金材料动态力学性能试验的基础上,结合理论分析和大量数值模拟,建立在碰撞力集中载荷和均布压力共同作用下钛合金球柱组合结构的动屈曲判断准则,所得结果可以为深海装备水下航行安全性提供重要参考。

深海静水压力对环氧涂层/907A低合金钢体系失效行为的影响

目的探究深海静水压力作为单一因素影响涂层/金属体系的失效过程。方法在深海环境模拟实验装置中开展环氧涂层/907A低合金钢体系的浸泡实验,从电化学阻抗谱、涂层湿附着力、涂层微观形貌及其化学结构等方面分析涂层的失效机理。结果当静水压力为0.1 MPa和15 MPa时,涂层阻抗值分别下降至3.83×10^(6)Ω·cm^(2)和6.28×104Ω·cm^(2),涂层湿附着力分别下降至2.76 MPa和2.31 MPa。在不同静水压力下,水在涂层中的前期扩散形式均符合Fick扩散定律,而涂层下水的扩散系数从1.05×10^(-9) cm^(2)/s增加至2.39×10^(-9) cm^(2)/s。随着静水压力的升高,环氧涂层表面的孔隙以及裂纹不断发展并出现了鼓泡。在静水压力为0.1 MPa条件下腐蚀产物以γ-FeOOH为主,静水压力升高后腐蚀产物Fe_(3)O_(4)含量明显增加,除锈后的腐蚀坑直径由15μm增加至25μm。结论高静水压力可以加速腐蚀性介质向涂层内部以及涂层/金属界面的渗透,涂层湿附着力迅速下降,涂层失效更加严重。高静水压力能够促进腐蚀产物中高电化学活性Fe_(3)O_(4)的生成。此外,静水压力下涂层失效的主要原因是物理结构受到破坏。

基于宏观地质模型分类的深埋输水隧洞衬砌外水压力研究

衬砌的外水压力对富水深埋隧洞衬砌厚度和排水方案的确定具有重要意义。现有研究往往忽略宏观地质条件对渗流场的影响规律分析,导致深埋隧洞外水压力估算结果和衬砌设计方案缺乏可靠性的评价。论文依托引汉济渭秦岭输水隧洞工程,将富水地区深埋隧洞概化为分水岭下、傍山区域、河流下3种代表性的宏观地质环境模型,研究地质条件因素和工程措施对围岩渗流场和衬砌外水压力的影响规律和机理。结果表明:①洞顶地下水高度相同和衬砌不透水条件下,分水岭隧洞周围地下水的渗流方向以竖向为主;河流下隧洞周围地下水的渗流方向以水平为主。分水岭隧洞、傍山区域隧洞、河流下隧洞外水压力折减系数依次增大。分水岭下隧洞外水压力折减系数随着埋深增大而增大,依次为0.72、0.77、0.84;而傍山隧洞、河流下隧洞外水压力折减系数几乎不变,分别是0.91、0.91、0.93和0.95、0.96、0.96。②采取相同排水措施后,随着埋深增大,分水岭隧洞外水压力折减系数依次为0.15、0.42、0.64,降压效果最好;而傍山隧洞、河流下隧洞外水压力折减系数分别是0.48、0.67、0.77和0.63、0.80、0.83,降压效果逐渐变差;③隧洞埋深1200 m时,分水岭、傍山和河流下隧洞外水压力折减系数随着围岩渗透系数的增大外水压力折减系数分别介于0.43~0.73、0.67~0.89和0.80~0.95,均呈现外水压力随着隧洞埋深增大而增大的规律性。研究成果具有普适性,可以从隧洞宏观水文地质条件与外水压力折减系数的规律性评估富水地区隧洞衬砌抗水压设计的合理性。

基于合理近似和求解方程思路的外压容器壁厚设计方法

现行《化工设备机械基础》教材中外压容器的设计包括“解析法”和“图算法”两种方法,但这两种方法均需要预先假设筒体的名义壁厚δ_(n),再代入公式或利用算图完成后续设计,直到许用外压[p]不小于设计外压p_(c)且尽量接近为止。初始猜测的名义壁厚很难一次性满足要求,存在有余和不足的问题,尤其是缺少经验的初学者,需要不断试差,重复繁琐的操作才能完成设计。本文利用合理近似和解方程的方法直接得到有效壁厚δe,进而求取名义壁厚δ_(n),可大幅度简化外压容器设计计算。

BI@ZIF-8/EP涂层的制备及在深海压力下的防护性能研究

目的制备负载苯并咪唑(BI)的BI@ZIF-8粒子,研究BI@ZIF-8/EP涂层在2种静水压力下的失效行为。方法制备并表征BI@ZIF-8粒子。制备BI@ZIF-8/EP涂层,在常压(0.1 MPa)和模拟深海压力(6 MPa)开展浸泡实验。通过微观形貌、失光率、色差、附着力、红外光谱、电化学阻抗谱等手段进行涂层失效行为对比分析。结果成功制备了BI@ZIF-8粒子;在相同压力条件下,BI@ZIF-8/EP涂层具有更高的附着力和阻抗值;同种涂层在6 MPa下退化更加严重,附着力和阻抗值下降速率增大;随着浸泡时间的延长,6 MPa下BI@ZIF-8/EP涂层中的BI特征峰强度明显减弱,2种涂层的主要特征峰强度均有下降。结论ZIF-8粒子中的咪唑基,能增加环氧涂层交联密度,降低侵蚀性粒子渗透速率;高静水压能显著加速侵蚀性粒子向涂层内部的扩散,并加速有机涂层失效进程;BI分子和2-Melm分子中N原子的孤电子对与Fe原子的空轨道能在金属基体表面形成吸附膜,并且Zn^(2+)和OH^(−)能在金属基体表面形成沉积膜,有效减缓了金属腐蚀。此外,2种涂层的退化机制不受静水压力升高的影响。

东海盆地西湖凹陷平湖斜坡始新统平湖组成岩相类型及对储层的控制

为了在深埋藏、强非均质性背景下寻找相对优质储层,本文以东海盆地西湖凹陷平湖组为例,基于直观微区观测、间接压汞表征及孔渗分析相结合的方法,在储层沉积学分析的基础上,先划分成岩相类型,进而明确不同成岩相的差异储集能力特征,评价成岩相储集能力。结果表明:平湖组沉积于河流和潮汐双向水动力条件的三角洲-潮坪体系,砂体多发育于水下分流河道、河口坝、潮道、砂坪和混合坪中,以细粒和极细粒为主,主要为长石岩屑砂岩和岩屑长石砂岩;基于成岩作用类型的强度差异将成岩相划分为3类,包括长石溶蚀相、富塑性压实相和钙质胶结相;同一成岩相类型孔渗特征和孔隙结构特征均一,而不同成岩相之间物性差异显著;以孔隙度、渗透率、最大连通孔喉半径为标准对3类成岩相进行量化参数分级评价,长石溶蚀相孔隙度>15%,渗透率>10.0×10^(-3)μm^(2),最大连通孔喉半径>5.0μm,物性条件优于富塑性压实相和钙质胶结相,优选出长石溶蚀相为最有利的储层砂体类型。