TIME-DOMAIN RESPONSES OF IMMERSING TUNNEL ELEMENT UNDER WAVE ACTIONS

The time domain responses of the tunnel element under wave actions during its immersion are investigated based on the linear wave diffraction theory. The integral equation is derived by using the time-domain Green function that satisfies the free water surface condition in the finite water depth, and is solved by the boundary element method. The motion equations of the tunnel element are solved by the fourth order Runge-Kutta method. A comparison between the computed and measured results reveals that the numerical model can effectively simulate the motion responses of the tunnel element and the cable tensions when the motions of the tunnel element are within some limit. Taking the tunnel element of 100 m in length, 15 m in width and 10 m in height as an example, the computational results of the motion responses of the tunnel element and the cable tensions in different immersing depths are obtained under different incident wave conditions.     

防城企沙供水工程跨江管施工

以防城企沙供水管网工程跨江管段采用敷设直径1.2 m PE管施工的实例,详细介绍了PE管跨江段的施工工艺以及施工中应注意的一些问题。     

海河隧道工程防洪影响分析

海河隧道线路全长2 3034 m,其中主河道沉管段长240 m,沉管断面宽度374 m,高98 m,共设置两节,每节120 m。河道沉管段采用水中沉管法施工。管段安装会对河道的防洪安全产生较大的影响,故须对河段的水沙条件有严格的要求。本文采用三维分层水流泥沙数学模型,通过错层处理,较好地解决了同层网格产生急剧变化,在突变点处隔层网格物理量的影响远大于层间网格的影响问题。对隧道管段悬浮状态、沉放过程中的过流能力、水流流态和河段水流泥沙运移规律进行了深入分析,提出管段对河段水沙的影响程度及解决措施。本研究拓展了三维分层水流泥沙数学模型的应用范围,为保证工程施工安全提供了理论基础。     

DISTRIBUTION OF WAVE-INDUCED EXCESS MOMENTUM FLUXES OVER DEPTH AND APPLICATION TO THREE-DIMENSIONAL NUMERICAL MODELING OF WAVE-CURRENT INTERACTIONS

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沉管隧道振动台模型地震反应试验研究

为研究沉管隧道在饱和砂土场地中的地震反应规律,以某超长沉管隧道为研究对象,设计了装配式柔性橡胶接头,开展了饱和砂土中的多段式沉管隧道振动台模型试验。沉管隧道模型由3节微粒混凝土管段和两节装配式柔性橡胶接头构成。试验通过孔隙水压力计、加速度计和应变片监测了地基的孔压、结构及其周围土层加速度和结构应变。试验结果表明:中小震时地基土并未液化,大震时模型表层地基土发生液化。地基土液化后,低频地震波对结构影响更大。结构与周围土体的加速度及其傅里叶谱形状吻合较好,结构加速度小于土体加速度,沉管隧道结构的地震反应受地基土的影响较大。靠近接头监测点的加速度反应更大,管段之间出现相对运动,接头是沉管隧道抗震设计的关键部位,模型结构的中墙、侧墙与结构顶板节点为此类型隧道的不利位置。试验研究成果为隧道抗震研究提供参考。     

内河交汇处沉管隧道基槽回淤厚度研究

基槽回淤对沉管隧道平顺度影响较大,对其防水性能产生威胁。为研究两河交汇处沉管隧道基槽的回淤特性,依托如意坊沉管隧道,构建数值计算模型,对比实际监测值以验证模型的适用性,进而揭示内河交汇处沉管隧道基槽回淤规律。研究结果表明:模型中河流流速与实际监测数据误差较小,验证了模型的适用性;内河交汇处基槽淤积厚度整体呈中间大两端小、上游大下游小的规律;回淤分布受空间影响较大,基槽底脚淤积显著,且坡顶淤积厚度显著小于坡底;回淤量随时间的延长其敏感性逐渐下降;基槽开挖后,回淤均值为10 cm,将影响沉管隧道的施作,现场须采取清淤措施进行处置。研究成果为两河交汇处沉管隧道基槽回淤分析与治理提供了指导。     

RESEARCH ON THE METHOD AND CALCULATION OF THE NEW SLENDER-SHIP WAVE RESISTANCE THEORY

BRIEFINTRODUCTIONOFTHEPAPER :　InChapter 1,anoverviewmainresearchactivitiesaboutwaveresistancesincethefamouspioneeringstudyofMichellin 1898aregiven .InChapter 2 ,Noblesse’snewslender shiptheoryofwaveresistanceisinvestigatedindetail.InChapter 3,calculationformulasofzeroth first andsecond orderwaveresistancearederivedandcorrespondingcalculation programsarecom piled .InthesingleanddoubleintegralpartsofGreen’sfunction ,thekernelfunctionofwave makingresistanceexpression ,specialfunct…     

高水差条件下内河沉管隧道健康监测系统研究

以建设中的国内最大内河沉管隧道——南昌红谷隧道为工程依托,针对其高水差、长大管节、地层条件复杂、隧道纵坡变化大等特点,设计了针对该沉管隧道的结构健康监测方案,并构建了一套健康监测评估系统。重点论述了管段接头张开和错位、管段不均匀沉降、剪切键受力的监测方法以及健康评估指标体系的构建过程。该监测系统可实现对隧道多项位移、内力等健康指标数据的实时全自动测取与传输,并可自动进行隧道健康状态评估,给出预警、报警、管理、养护建议。     

几种常见截面形式的水锤波速及其影响因素的分析

研究水电站引水系统的水锤现象。无论对引水道的设计还是运行都具有重要意义。前人对水锤波传播理论的研究推导出了圆形管道截面及方（矩）形薄壁管的波速表达式，但随着有压引水道多种截面型式的出现，这些表达式就远远不能满足要求。目前，对非圆形截面，一般都参照圆形截面的水锤波速，进行分析计算，这必然影响水锤压力及水力共振计算结果的准确性。因此，本文采用结构力学方法及有限元方法，绘制出一组波速曲线；并在分析各种影响因素的基础上，绘出了常见引水道截面型式的波速范围。     

THE COMPARATIVE STUDY OF VENTILATED SUPER CAVITY SHAPE IN WATER TUNNEL AND INFINITE FLOW FIELD

In order to understand the difference of ventilated supercavity in water tunnel and infinite flow field, 3-D numerical simulations are carried out to obtain the ventilated supercavity in above mentioned conditions based on RANS equations, using the finite volume method and SST turbulence model in the framework of the two fluid multiphase flow model. The numerical method adopted in this article for the infinite flow field and water tunnel experiments is validated by comparing results with those of empirical formulas and experimental data. On this basis the difference between water tunnel experiments and infinite flow field is studied, including the influence of the route loss and the blocking effect in the water tunnel. Finally, some suggestions are made for water tunnel experiments.     

SIMULATION OF HYDRAULIC TRANSIENTS IN HYDROPOWER SYSTEMS USING THE 1-D-3-D COUPLING APPROACH

Although the hydraulic transients in pipe systems are usually simulated by using a one-dimensional (1-D) approach, local three-dimensional (3-D) simulations are necessary because of obvious 3-D flow features in some local regions of the hydropower systems. This paper combines the 1-D method with a 3-D fluid flow model to simulate the Multi-Dimensional (MD) hydraulic transients in hydropower systems and proposes two methods for modeling the compressible water with the correct wave speed, and two strategies for efficiently coupling the 1-D and 3-D computational domains. The methods are validated by simulating the water hammer waves and the oscillations of the water level in a surge tank, and comparing the results with the 1-D solution data. An MD study is conducted for the transient flows in a realistic water conveying system that consists of a draft tube, a tailrace surge tank and a tailrace tunnel. It is shown that the 1-D-3-D coupling approach is an efficient and promising way to simulate the hydraulic transients in the hydropower systems in which the interactions between 1-D hydraulic fluctuations of the pipeline systems and the local 3-D flow patterns should be considered.     

PIV TECHNIQUE AND ITS APPLICATION IN SHIP HYDRODYNAMICS

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ESTIMATION OF DIRECTIONAL SPECTRUM AND REFLECTED COEFFICIENT OF INCIDENT AND REFLECTED WAVE IN PHASE-LOCKED WAVE FIELD

This paper analyses and compares the property of the Modified Bayesian Directional spectrum analysis Method （MBDM） and the Modified Maximum Lkelihood Method （MMLM） that can he used to estimate directional spectrum and reflected coefficient of phase-locked wave field overlapped by multi directional irregular incident and reflected waves. The numerical test verifies the results under different wave conditions, different measurement systems, and different reflection features. The computation speed and stability of the two methods is also compared. The analysis addresses that the MBDM is better than the MMLM for directional spectrum estimating, while the MMLM is better than the MBDM for reflected coefficient estimation and calculating speed and stability.     

NUMERICAL SIMULATION OF A MATHEMATICAL MODEL FOR WAVE PROPAGATION ON NON-UNIFORM CURRENT AND DEPTH

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THEORETICAL AND EXPERIMENTAL STUDIES OF HYDRAULIC CHARACTERISTICS OF DISCHARGE TUNNEL WITH VORTEX DROP

The velocities at given points in the volute chamber,the contracted section and the vertical dropshaft of a discharge tunnel with vortex drop were measured by a small specially designed L-shaped tube,as Laser Doppler Velocimetry(LDV) or Particle Image Velocimetry(PIV) would not work there due to the special structure of the discharge tunnel with vortex drop.Hydraulic empirical formulas were proposed to predict the velocities and the angles of the velocities made with the vertical direction θ.The theoretical analysis results were in good agreement with experimental data.Therefore,the method proposed in this paper can be used to analyze related characteristics of discharge tunnels with vortex drop.Additionally,different model scales were considered to predict the cavitation characteristics on the wall of a dropshaft in practical engineering.     

内置软管的管道水锤波速理论计算公式

内置软管或软条是水锤模型实验中降低水锤波速的有效措施之一,然而目前没有相应的理论计算公式,具体波速只能通过实验测定.本文应用弹性力学理论,导出内置软管的水平管道水锤波速公式,并通过理论分析和与模型实验以及有限元计算的对比,验证了计算公式的可靠性,最后对影响水锤波速的因素进行了敏感性分析,结果表明软管的弹性模量和尺寸等参数对水锤波速的影响较大,而软管泊松比、初始水压力和软管内充气压强的影响相对较小,并且软管弹性模量越小、外径越大则管道水锤波速越小.在尺寸相同的条件下,内置含钢线软管是降低水锤波速的最优方案.     

最小阻力船型优化研究

本文基于线性兴波阻力理论，把控制尾流分离作为约束条件，利用优化计算方法对设计水线下船体外形进行优化研究。以数学船型Ｗｉｇｌｅｙ船型为母型进行了计算，分别讨论了最小兴波阻力船型和最小总阻力船型的确定方法，并将所得到的改良船型进行了船模阻力试验，结果证实了本优化设计方法的可靠性。     

白鹤滩尾水隧洞明满流对水电站稳定性的影响

白鹤滩水电站单机容量为1 000 MW,规模居世界第二。对于水电站而言,引水发电系统的稳定性尤为重要,而该水电站的尾水隧洞存在着明满流现象,严重影响到了引水发电系统的稳定性。为此,采用特征隐格式下的虚拟狭缝法,分析了尾水隧洞内不同流态对机组稳定性及尾水调压室水位波动的影响。分析结果表明：当明满流段流态为明流时,可以加速调压室水位波动收敛,有利于输水系统的稳定;当流态为明满过渡流时,其压力脉动现象会导致机组调节品质变差,不利于输水系统的稳定。此外,明满流段的长度对机组调节品质影响很小,长度的选取不受输水系统稳定性限制。研究成果可为类似输水系统设计和研究提供参考。     

狭窄水域中单点系泊/拖带船舶动力学行为的试验研究

对单点系泊／拖带船舶在狭窄水域中的动力学特性进行了试验研究。找到了船模的四种稳定运动模式；探讨了不同来流速度和系缆长度对于船只的动力学响应和系缆力的影响。试验表明，船模运动呈现出典型的非线性特征，观察到了吸引子的共存、跳跃和Hopf分岔现象，系缆张力的大小与船舶的动力学行为密切相关，振转运动(鱼尾状摆动)发生时的系泊力远大于船只静止时的缆绳张力；振转运动中的突发系缆载荷可能是导致缆绳断裂的重要原因。与宽广水域相比，狭窄水域中的系泊／拖带船只更宜发生振转运动。     

不规则波中拖航系统的模型试验

以１：３０尺度比对由２６００马力拖船、重任７０２驳船及拖缆组成的拖航系统在不规则波中完成了模型试验，探讨了缆长、浪向、航速等对拖航系统的运动性能与拖缆力的影响。