Seabed Ground Improvement in Coastal Reclamation Area by Heavy Tamping After Rockfilling Displacement

Considering the characteristics of seabed ground in coastal reclamation area, ultra soft clay improvement method by heavy tamping after rockfilling displacement was proposed combined with a case study. The improvement mechanisms of the method can primarily be attributed to rockfilling displacement (RD), dynamic compaction (DC), dynamic replacement (DR) and dynamic replacement and mixing (DRM). For the case study given in this article, heavy tamping construction program was proposed based on field pilot tests. Furthermore, the effectiveness of the proposed ground improvement method was verified through in situ plate load test, sand fill test and the analyses of observed settlement data. Thus, the method of heavy tamping after rockfilling displacement is applicable for the improvement of seabed ground in coastal reclamation area. It is proposed for similar projects that heavy tamping of fills may be performed by layers and correspondingly tamping energy increased to further enhance the improvement effect of DC, DR and DRM. In addition, delayed improvement effect or time effect of soil mass after heavy tamping is still an issue to be further studied.     

近距离照射联合贻贝提取物对荷瘤鼠治疗效果的研究

观察了近距离照射联合贻贝提取物对Ｕ１４鼠免疫功能的影响,以期探讨贻贝提取物在放射治疗中的作用。结果表明,贻贝提取物使荷瘤鼠因近距离照射而下降的免疫指标明显回升,包括脾脏ＮＫ细胞杀伤活性,丝裂原诱发的淋巴细胞转化强度和外周血白细胞总数及脾指数,亦有效增强放疗的治疗效果。     

重金属胁迫下四种红树植物幼苗生理响应特征

研究了四种红树植物红海榄、秋茄、木榄、角果木幼苗在不同浓度重金属水溶液胁迫28天后的生理生化指标变化特征,包括可溶性蛋白含量、超氧化物歧化酶（superoxide dismutase, SOD）、过氧化物酶（peroxidase, POD）活性和氧化损伤标志物丙二醛（malondialdehyde, MDA）含量。研究结果表明四种植物叶片内的SOD、POD活性均呈现出先升高后下降趋势,10倍重金属水溶液中的红海榄,5倍重金属水溶液中的秋茄和木榄,以及1倍重金属水溶液中的角果木具有较好的抗氧化酶活性,能有效清除活性氧,减小氧化损伤。在同等浓度重金属水溶液处理下,MDA含量结果显示红海榄受损程度最轻,秋茄、木榄受损程度居中,角果木受损程度最重。红海榄抗重金属胁迫能力强于秋茄、木榄,角果木抗重金属能力最弱。上述四种红树植物对重金属的抗性结果说明红树科植物具有较强的抗污染能力,这对于我国红树林生态修复与保护具有重要的指导意义。     

VIV response of a long flexible riser fitted with strakes in uniform and linearly sheared currents

An experimental investigation was conducted on a flexible riser with and without various strake arrangements. The aim of the present work was to further improve the understanding of the response performance of the vortex-induced vibration (VIV) of a riser with helical strakes. Two current profiles, including uniform and linearly sheared flows, were simulated. The uniform current was simulated by towing the riser model in one direction using the towing carriage, and the linearly sheared current was simulated by fixing one end of the riser and using a driven cantilever to traverse a circular arc. Based on the modal superposition method, the displacement responses were obtained from the measured strain. Strakes with different heights and pitches were analysed, and response parameters such as the displacement response and fatigue damage were studied. The results of the bare model test show that the lock-in phenomenon displays multi-order characteristics, and the VIV displacement decreases with an increased order of the lock-in regime. The results of the straked model test indicate that the response characteristics of a bare riser can be quite distinct from those of a riser with helical strakes, and the response performance depends closely on the geometry of the strake configuration.     

Experimental Study on Response Performance of VIV of A Flexible Riser with Helical Strakes

Laboratory tests were conducted on a flexible riser with and without helical strakes. The aim of the present work is to further understand the response performance of the vortex induced vibration (VIV) for a riser with helical strakes. The experiment was accomplished in the towing tank and the relative current was simulated by towing a flexible riser in one direction. Based on the modal analysis method, the displacement responses can be obtained by the measured strain. The strakes with different heights are analyzed here, and the response parameters like strain response and displacement response are studied. The experimental results show that the in-line (IL) response is as important as the cross-flow (CF) response, however, many industrial analysis methods usually ignore the IL response due to VIV. The results also indicate that the response characteristics of a bare riser can be quite distinct from that of a riser with helical strakes, and the response performance depends on the geometry on the helical strakes closely. The fatigue damage is further discussed and the results show that the fatigue damage in the CF direction is of the same order as that in the IL direction for the bare riser. However, for the riser with helical strakes, the fatigue damage in the CF direction is much smaller than that in the IL direction.     

Experimental Study on Response Performance of VIV of A Flexible Riser with Helical Strakes

Laboratory tests were conducted on a flexible riser with and without helical strakes. The aim of the present work is to further understand the response performance of the vortex induced vibration(VIV) for a riser with helical strakes. The experiment was accomplished in the towing tank and the relative current was simulated by towing a flexible riser in one direction. Based on the modal analysis method, the displacement responses can be obtained by the measured strain. The strakes with different heights are analyzed here, and the response parameters like strain response and displacement response are studied. The experimental results show that the in-line(IL) response is as important as the cross-flow(CF) response, however, many industrial analysis methods usually ignore the IL response due to VIV. The results also indicate that the response characteristics of a bare riser can be quite distinct from that of a riser with helical strakes, and the response performance depends on the geometry on the helical strakes closely. The fatigue damage is further discussed and the results show that the fatigue damage in the CF direction is of the same order as that in the IL direction for the bare riser. However, for the riser with helical strakes, the fatigue damage in the CF direction is much smaller than that in the IL direction.     

Morphodynamics and cobbles behavior in and near the surf zone

The evolution of an initially flat sandy slope and the dynamics of large objects (cobbles/mines) emplaced on it are studied in a laboratory wave tank under simulated surf conditions. Upon initiation of wave forcing, the initially flat beach undergoes bedform changes before reaching a quasi-steady morphology characterized by a system of sand ripples along the slope and a large bar near the break point. Although the incoming wave characteristics are held fixed, the bottom morphology never reaches a strict steady state, but rather slowly changes due to the migration of ripples and bar transformation. When the wave characteristics are changed, the bedform adjusts to a new quasi-steady state after a suitable adjustment time. Studies conducted by placing model cobbles/mines on the evolving sandy bottom subjected to wave forcing show four distinct scenarios: (i) periodic cobble oscillations with zero mean displacement and small scour around the cobbles, (ii) mean onshore motion of relatively light cobbles, (iii) periodic burial of relatively heavy cobbles when their sizes are comparable to those of sand ripples, and (iv) the burial of relatively large cobbles under the bar, when the bar migrates due to changes of incoming waves. Quantitative data on the characteristics and dynamics of the bedform, including ripple-formation front propagating down the slope, ripple growth and drift, and flow around ripples, are presented. Physical explanations are provided for the observations.     

八所港矿砂码头混凝土腐蚀现状分析

针对海南八所港矿砂码头服役近30年的混凝土梁、柱和70年的甬道等结构腐蚀状况进行现场调研,发现钢筋混凝土结构出现钢筋锈蚀、混凝土剥落,部分混凝土严重破损。测量了其混凝土梁、柱、甬道等不同位置混凝土和铁锈中氯离子含量,分析了局部环境对氯离子分布的影响。根据调研结果总结分析了其破损原因。结果表明混凝土中氯离子分布呈现规律性变化,且铁锈中的氯离子含量远小于混凝土中氯离子含量。     

喷冲气举机构试验研究

介绍了气举机构的工作原理,并对正压冲固平台特定沉贯施工条件下的多种气举泵设计方案进行了来列试验研究．试验研究获取了气举装置的骑气量与排水量的关系和气举高度特性以及各种泵体结构参数,为正压冲固平台基础的沉贯设备设计提供了科学依据．     

磷化氢在海水中的转化及其影响因素研究

通过室内模拟实验,研究了磷化氢在海水中的转化过程,分析了光照条件、氧化条件、通入方式等环境因子对磷化氢转化的影响。结果表明,在日光照射条件下,磷化氢在海水中可部分转化为磷酸盐,但转化率相对较低,转化过程复杂;环境因子在磷化氢转化过程中起重要作用,日光照射、紫外光照射、氧化条件等均能促进海水中磷化氢向磷酸盐和总磷的转化,在紫外光照射条件下检测到磷化氢向磷酸盐的最大转化率为66.6%。本研究对探索磷化氢在海洋环境生物地球化学循环中的作用具有重要意义。     

多层砂土地基扩底桩单桩抗压模型试验及颗粒流模拟研究

利用室内半模试验和颗粒流数值模拟,揭示多层砂土地基扩底桩单桩抗压承载特性及变形特征。结果表明,通过对比分析极限承载力与H_h/D(持力层厚度与扩大头直径之比)的关系可以看出,单桩的抗压极限承载力随H_h/D逐渐增加,当H_h/D超过2.0时,极限承载力基本不再增加,此时的单桩抗压极限承载力稳定在300.01~303.25 N,是H_h/D=0.5时极限承载力(183.83 N)的1.65倍。扩大头下部土体发生局部压缩-剪切破坏,破坏面从扩大头底面边缘向斜下方扩展,在水平方向影响范围达到最大后逐渐向桩内侧收缩;荷载作用越大,地基破坏区域越大,相应的极限抗压承载力也越大;持力层厚度增加,扩大头分担的荷载比例增大,分担的荷载达到稳定需要的桩顶位移也越大,H_h=0.5 D试验扩大头分担的荷载比例稳定时为60%,对应的桩顶位移约为29 mm;桩顶位移达到33 mm后,H_h=1.0~3.0 D试验稳定在63%~65%之间;通过细观颗粒流理论对砂土移动特性的研究发现,持力层厚度从0.5 D增大至2.0 D,破坏面的起始扩展角度从31°增大至42°。数值模拟研究结果与模型试验数据吻合效果良好,证明该方法分析多层砂土地基扩底桩单桩抗压荷载传递机理是可行的。     

基于GPS-RTK技术的波浪能发电装置结构动态位移监测及滤波方法

利用全球定位系统实时差分技术（Global Positioning System Real-Time Kinematic,GPS-RTK）对波浪能发电装置进行结构变形监测得到的信号会存在噪声。针对这个问题,本文提出一种结合巴特沃斯（Butterworth）滤波器和自相关函数经验模态分解（Empirical Mode Decomposition,EMD）的滤波降噪算法,利用动态位移仿真信号进行了实验验证。结果表明：该滤波算法能够有效降低装置动态位移监测数据中噪声的影响,利用滤波算法对仿真信号进行降噪处理之后,可以提取出信号中包含的结构固有频率。     

Experimental Investigation of Disturbing the Flow Field on the Vortex-Induced Vibration of Deepwater Riser Fitted with Gas Jetting Active Vibration Suppression Device

An experimental investigation on the disturbance effect of jet-type active vibration suppression device on vortexinduced vibration of deep-sea riser was carried out in the wave-flow combined flume. The vibration suppression device was designed in which the jet pipe was horizontally fixed to the front end of the riser. By varying three different excitation spacings and multi-stage outflow velocities, the influence law of the dominant frequency,dimensionless displacement and other dynamic response parameters was studied under different excitation spacings,and the mechanism and sensitive characteristics of the disturbance suppression were explored. The results indicate that the variation of excitation spacing makes gas curtain enter the strong disturbed flow region at different velocities and angles, and the coupling relationship between excitation spacing and reduced velocity is the key factor to enter the strong disturbed flow region to achieve the optimal disturbance suppression. In the strong disturbed flow region,the influence of gas curtain on the dominant frequency is obviously affected by the flow velocity, while the vibration displacement is stable at the same amplitude and is weakly affected by the flow velocity. Gas curtain can effectively disturb the formation of vortex shedding, destroy the strong nonlinear coupled vibration of the riser, and achieve better vibration suppression effect. In the weak disturbed flow region, the vortex length of the riser tail is prolonged,the strong nonlinear coupled vibration of the riser is gradually restored, and the vibration suppression effect of the device gradually decreases.     

滩涂匡围海堤选线对邻近涵闸排水的影响分析--以条子泥西侧岸滩仓东片匡围为例

淤泥质海岸后方大面积的低地平原主要通过海岸上建设的涵闸排水,潮滩匡围对沿海涵闸排水的影响是围垦工程必须解决的问题。文章以条子泥西侧岸滩仓东片匡围为例,探讨了不同堤线方案下邻近闸下流槽各种落潮水量组成及其维护闸下排水能力的有效性。结果表明,合理的滩涂匡围堤线方案,在平均潮汛及一般大潮汛时对邻近闸下排水能力影响较小,而在风暴潮或秋季大潮汛时有一定影响,但可以通过若干次冲淤保港来解决。     

沉箱基础对摇板式波浪能装置水动力性能影响研究

摇板式波浪能转换装置具有频率响应范围广、可靠性好、常规海况下转换效率高、建造成本低等优点。基于势流理论建立具有沉箱基础的摇板式波浪能装置水动力性能的解析解。将解析结果与文献中已有结果和边界元数值结果进行了对比,验证了解析解求解过程的正确性。通过算例分析,研究了波浪入射频率、沉箱基础高度、沉箱基础宽度、摇板位置、摇板厚度和摇板密度对装置能量俘获效率的影响。研究结果表明：采用合适高度的沉箱基础能显著提升装置性能;长波海况下,摇板铰接在沉箱基础背浪侧上表面时装置性能更佳,而短波海况下,摇板铰接在沉箱基础迎浪侧上表面更为合理;沉箱基础宽度的推荐值为0.5到1.0倍水深;适当减小摇板厚度能够提升装置性能;应优先选用密度较大的摇板。     

Optimisation of arrays of flap-type oscillating wave surge converters

In this paper a finite array of hinged flap-type wave energy converters are modelled using a mathematical approach. These are illustrative of the Oyster device of Aquamarine Power Ltd.¹ A novel semi-analytic solution method is presented for a set of boundary-value problems involving the scattering and radiation of waves by thin barriers used to model the device hydrodynamics. The approach makes use of the geometry to apply Fourier transforms, deriving non-singular integral equations in terms of the jumps in pressure across the flaps. These are then solved numerically using a highly efficient Galerkin expansion method. The focus of the results is on optimisation. We suggest optimal parameters for a single device, identifying flap length as crucial to device performance. This optimisation is then carried through to arrays with optimal arrangements and spacings being determined for a model sea state. Here, the lateral displacement of the devices emerges as a critical factor in optimal array configuration.     

基于边界面模型的砂土中板锚循环承载力数值分析

利用带误差控制的显式积分算法,将一种适用于饱和砂土排水循环动力分析的边界面塑性模型编写成可供有限元软件调用的用户自定义材料子程序。建立土体单元有限元数值模型对Toyoura砂的静、动排水三轴试验进行模拟,验证了模型具备合理描述砂土在不同荷载条件下力学响应的能力。建立饱和砂土中板锚循环承载分析的数值模型,针对板锚在砂土中的单调抗拔特性和循环承载特性进行数值分析,得到了与模型试验一致的荷载—位移响应规律。考察循环荷载要素对板锚循环承载特性的影响,结果发现,随着循环荷载的施加,板锚永久位移逐渐累积,循环荷载会导致板锚持续移动,循环幅值越大,初始位移和位移变化率越大;循环均值越大,初始位移越大,但位移变化率越小。     

泉州湾海域表层沉积物矿物碎屑分布特征及其环境意义

对泉州湾13个表层沉积物样品进行了矿物碎屑定量分析．通过矿物分析，发现泉州湾不同站位的轻、重矿物组分、含量和表征存在差异．根据矿物的分布和组合特征．将耒州湾划分为4个组合区，不同组合区所处沉积环境是不同的．分析表明，研完区表层沉积物的碎屑矿物具有明显的亲陆性，物质来源主要为河流输砂和沿湾海岸侵蚀来砂，且其分布受物源、水动力条件和矿物物理性质等因素所控制。     

Experimental Study on Hydrodynamic Characteristics of Vertical-Axis Floating Tidal Current Energy Power Generation Device

To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device (VAFTCEPGD), a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.