门架式水力插板桩的抗滑移稳定性分析

门架式水力插板桩是1种新型的空间挡土结构,其抗滑移稳定性计算目前尚无成熟方法.文中给出了直角坐标系下门架式水力插板桩抗滑移稳定性计算的简化Bishop积分方法和安全系数表达式,并编制了安全系数计算程序.通过1个算例,将此方法的计算结果与GEO-Slope有限元软件的计算结果进行了比较,表明了该方法是可行的.探讨了土体内摩擦角、粘聚力、桩入土深度和双排桩间距对结构稳定性的影响,得出了当土体的内摩擦角和粘聚力较小时,应通过增加桩的入土深度来提高门架式水力插板桩的抗滑移稳定性等一些有意义的结论.     

波浪作用下方块石护面稳定性研究

护面是海堤和护岸的重要结构,直接抵御波浪作用,可采用人工块体、块石等,种类繁多。采用紧密排列方块石作为护面结构是一种景观性较好的型式,依据方块石厚度不同能抵御不同大小的波浪作用。干砌条石及干砌块石护面曾有一些规范给出过计算方法,但现行规范没有相关内容可供设计参考,已有计算方法的理论分析还存在不足。当波浪与斜坡堤相互作用时,方块石护面出现位移或脱落可能发生在波浪回落最低阶段、波浪破碎打击阶段及破后爬高水流作用阶段,通过研究得到了不同阶段波浪对方块石护面作用力的计算方法。在波浪回落最低阶段,考虑了护面及其下方垫层渗透性影响,通过理论分析建立了低渗透护面浮托压强计算模型,采用物模试验将计算结果与试验测量值进行了对比分析,结果表明总体趋势符合,量值接近;在波浪破碎冲击阶段,基于射流冲击作用原理,提出了波浪在斜坡面破碎冲击压强计算方法,通过试验分析了波浪破碎水深波高比与破波相似参数的关系,利用浅水波理论计算了波浪破碎冲击水流流速;在爬高水流作用阶段,提出了水流引起的方块石护面垂直浮托力及水平拖曳力的计算方法,通过试验结果拟合了浮托力系数和拖曳力系数,验证了水流作用下护面的受力特征。最后,针对方块...     

透空式水平板波浪上托力冲击压强试验研究

首先对以往波浪作用下透空式平板上托力研究进行了回顾,在此基础上,通过系列模型试验,对波浪上托力产生的机理进行了详细的分析和论述,认为透空式平板下波浪上托力主要由一个迅速上升的冲击压强和一个缓慢变化的压强构成,其中冲击压强通常远大于缓变压强,起主导作用,影响其大小的最直接因素为几何因素(即波浪冲击角)、动力因素(包括波高、波速等)和空气垫层因素,由此通过对各影响因素的分析,得到最大冲击压强计算公式,大量试验资料表明,该公式与实验值有着较好的一致性。     

Uplift Pressure of Waves on A Horizontal Plate

1 .IntroductionOwingtotheneedfordevelopingoffshoreresources,moreandmorehollow trussedstructuresareconstructed ,suchasalongshorequays ,islandquays,artificialislands ,bollards ,maritimeplatforms ,etc .Thelargeentitypartofthosemaritimestructuresusuallyconsistsofahorizontalplateabovethestillwaterlevel,anditusuallysuffersfromwaveattacksandthuscaneasilybedestroyed .Toavoidsuchakindofaccidents ,themostimportantistoaccuratelyevaluatetheupliftpressuresofwavesontheplateundervariouswaveconditionsandbound…     

A note on uprighting of a ship floating upside-down

In many cases, capsized ships remain floating upside-down due to buoyancy of intact hull compartments and air cushions. Uprighting of such a ship is usually a complex salvage operation, which needs proper planning based on predictions of ship stability. This paper considers aspects affecting selection of the uprighting method, presents features of ship stability in the inverted mode and a procedure for calculating the required forces. Approximate formulae are derived for estimating the maximum lifting capacity necessary for uprighting a capsized vessel supported by buoyancy of the double bottom and double side compartments. The formulae are intended for quick estimations at the initial stage when no detail information may be available on the casualty. A practical salvage work is briefly described.     

海洋观测浮标体水中平衡性分析

海洋观测浮标系统应用广泛,浮标体的平衡性能是影响海洋观测浮标使用的重要因素之一(着重观测波浪等水文参数除外)。以一种主体直径为2.3 m的浮标体为例,运用动力学平衡理论,通过数学分析法进行推演计算,分析后得到了此浮标体的重心和浮心的位置。其中,重心位于主浮体的中轴线偏下位置;按照浮标体倾斜一定角度的情况下,推算出浮标体浮心位置,并由此得出其稳心的位置。依据计算,得出浮标体倾斜20°的情况下,此浮标体依然处于稳态平衡,理论结果表明此浮标体设计具有一定的可行性。通过海上实际测试,验证了理论计算分析的正确性。文中对浮标体平衡性的研究采用了理论分析与实验印证相结合的方法,其分析计算方法具有普适性,适用于其他型号的海洋观测浮标体,乃至所有水面浮体的平衡性分析,可为水面浮体设计提供借鉴。     

一种新型潜浮式深海地震仪的设计与试验

鉴于国内外海洋地震台网的缺乏, 本文介绍了一种面向全球海域应用的漂浮式海底地震接收系统(mobile earthquake recording in marine areas by independent divers, MERMAID)。针对潜浮式地震仪MERMAID浮标的研发过程, 建立了浮标的总体设计要求与典型工作循环流程, 设计了液压式浮力调节系统、机械结构等, 并对比分析了不同转速及负浮力下潜过程, 最后进行了实验室压力检测和千岛湖湖试。试验结果表明, 该浮标能在15MPa压力下保持良好的密封性与稳定性, 利用水听器可以有效地采集到天然地震纵波(P波), 同时计算各模块单个周期的能耗, 以验证设计指标。     

小型水下自航行器自沉浮装置设计与研究

文中对水下自航行器(Autonomous Underwater Vehicle,简称AUV)的自沉浮装置进行了详细设计与研究。通过对已有的自沉浮装置方案进行对比研究,设计了以高压气体吹除压载水舱的新型自沉浮装置,该装置具有结构简单、可靠性高和可维护性好的特点,并可实现模块化设计。最后,对装置的主要设计参数进行了计算与优化。     

An alternative approach to determine a vessel's center of gravity: the center of buoyancy method

The location of a ship's vertical center of gravity (KG) is an important measurement needed to estimate the initial stability of a vessel. Traditionally, this measurement is obtained by determining the metacentric height (GM) using results from the inclining experiment. Such an approach is valid only for hull forms that are inclined to a small angle such that the metacenter remains stationary. This paper documents an alternative method for finding KG, called the center of buoyancy (CoB) method, which is based on the location of the centroid of the displaced volume. While the center of buoyancy method is valid for all ships, it is especially suited for vessels of unusual form. For such vessels, the location of the metacenter may change significantly at small angles of inclination, thereby making the conventional inclining reduction inaccurate. This paper addresses the need for the center of buoyancy method and details the steps required for its application.     

Numerical simulation of the action on a warm convective cloud by hygroscopic particles

A one-dimensional numerical model of a warm convective cloud is presented. This model is used to study the effectiveness of the action on the cloud by hygroscopic particles with the aim of intensifying precipitation. The numerical simulation takes into account the processes of condensation, coagulation, and sedimentation of cloud droplets and makes it possible to obtain spatiotemporal characteristics of cloud development. A system of differential equations describing time variations in the temperature, pressure, and watervapor supersaturation during the adiabatic rise of a continuous air flow is solved. The evolution of the size distribution of cloud droplets is described by a kinetic equation. A continuous acting source of droplets with the size distribution calculated with consideration for condensation properties and dispersion characteristics of condensation nuclei (natural and additionally introduced during the action) is specified at the cloud-base level. The cloud top is formed owing to the evaporation of droplets in the barrier atmospheric layer over the cloud. The influence of changes in the barrier-layer height on the structure of cloud parameters and precipitation-formation processes is analyzed. The introduction of additional hygroscopic particles into a cloud is shown to act as a trigger mechanism initiating the processes of coagulation and sedimentation in the cloud medium. In this case, a positive effect of action by fine particles can be achieved if a certain reserve of sufficiently large droplets is present in the cloud. The results of calculating the dependence of the action effect on the height of the barrier layer, restricting cloud development, are presented.     

Integral bubble and jet models with pressure forces

Modifications of integral bubble and jet models including the pressure force are proposed. Exact solutions are found for the modified model of a stationary convective jet from a point source of buoyancy and momentum. The exact solutions are compared against analytical solutions of the integral models for a stationary jet that are based on the approximation of the vertical boundary layer. It is found that the modified integral models of convective jets retain the power-law dependences on the altitude for the vertical velocity and buoyancy obtained in classical models. For a buoyant jet in a neutrally stratified atmosphere, the inclusion of the pressure force increases the amplitude of buoyancy and decreases the amplitude of vertical velocity. The total amplitude change is about 10%. It is shown that in this model there is a dynamic invariant expressing the law of a uniform distribution of the potential and kinetic energy along the jet axis. For a spontaneous jet rising in an unstably stratified atmosphere, the inclusion of the pressure force retains the amplitude of buoyancy and increases the amplitude of vertical velocity by about 15%. It is shown that in the model of a spontaneous jet there is a dynamic invariant expressing the law of a uniform distribution of the available potential and kinetic energy along the jet axis. The results are of interest for the problems of anthropogenic pollution diffusion in the air and water environments and the formulation of models for statistical and stochastic ensembles of thermals in a mass-flux parameterization of turbulent moments.     

导管架下水过程中浮力及浮心精确计算

在导管架下水运动过程中,其组成杆元相对于海平面的位置复杂多样。在导管架下水参数计算和仿真时,为了计算导管架的浮力和浮心,经常采用估算的方法,由于误差比较大而影响了计算和仿真的精度。分析了导管架下水运动过程中杆元的各种状态,用解析的方法推导出导管架下水运动过程中的浮力和浮心的精确计算公式,提高了导管架下水参数计算及其模拟的精度。     

Analyzing intraannual variations in the energy characteristics of circulation in the Black Sea

The energy characteristics of circulation in the Black Sea have been numerically analyzed for 2006. The annually and seasonally averaged integral components of the budget of both kinetic and potential energies are considered. It is shown that, over the period under study, wind forcing, buoyancy force, and friction are the main factors determining variations in the mechanical energy of the Black Sea. During the cold months, wind forcing maximally contributes to the kinetic energy. In spring, the contribution made by buoyancy force is dominant. The values of buoyancy force are maximum within the upper quasi-homogeneous layer during the warm season and on horizons, where the waters of the cold intermediate layer are concentrated, during the fall–winter season.     

各向均匀外压力作用下环肋圆柱壳的稳定特性

各向均匀外压力作用下的环肋圆柱壳，在总稳定方面会出现异常特性，例如，其稳定性不能正常地随其刚度的增加而增大。本文根据环肋圆柱壳在三种外力状态下（仅受轴向均匀外压，仅受横向均匀外压和各向均匀外压），总稳定性随几何参数变化的规律，从理论上详细说明了异常特性的实质是仅受轴向外压的特性，最后用模型实验结果证明理论分析与研究的正确性。     

Underwater glider modelling and analysis for net buoyancy, depth and pitch angle control

Underwater glider is an autonomous underwater vehicle that glides by controlling their buoyancy and attitude using internal actuators. By changing the vehicle's buoyancy intermittently, vertical motion can be achieved. Characteristics of glider motion include upward and downward movement in a saw tooth pattern, turning and gliding in a vertical spiral motion and gliding without using thrusters or propellers. This paper presents the modelling and identification on net buoyancy, depth and pitching angle of an underwater glider system. A ballast tank subsystem is considered appropriate for the identification process since it is the main parameter for the motion control. By selecting the ballast rate as the input, three aspects of the dynamics of a glider can be observed: buoyancy, depth of the glider and pitching angle. The MATLAB System Identification Toolbox^TM is used to obtain a mathematical model of the glider ballast-buoyancy, ballast-depth and ballast-pitching angle conditioning system. The best three parametric estimation models are chosen, and the results of the comparison between simulated and estimated outputs are presented. The information obtained from the modelling and identification approaches are used for USM's Underwater Glider Prototype controller design. The information observed during this procedure are utilised for optimisation, stability, reliability and robustness analysis of the underwater glider.     

关于气浮筒群结构的静稳性

讨论了气浮筒群结构的静稳性问题 ,以三筒组合为算例 ,变化干舷、升沉和绕x轴、y轴的倾角α、β ,给出了静稳性的算法和初步结果。指出存在四个相关的姿态角 ,最后讨论了初始参数干舷的选取     

基于SolidWorks移动式平台稳性计算方法

提出一种利用SolidWorks进行移动式平台稳性计算的方法.应用VB.NET对SolidWorks进行二次开发,自动创建、修改平台的三维实体模型,并由此快速准确地求出体积、形心等稳性计算所需的参数,从而使平台稳性计算变得更加方便快捷而且精度更高.最后通过计算实例证明,利用该方法计算平台的稳性是切实可行的.     

陡波形立管涡激振动疲劳损伤参数敏感性分析

基于柔性杆理论和尾流振子模型计算陡波形立管的涡激振动响应;综合使用S-N曲线法、雨流计数法、Palmgren-Miner线性累积疲劳理论对立管涡激振动导致的疲劳损伤进行计算分析。并以MATLAB为平台编写相应计算程序,将本文计算得到的静力分析结果、固有频率和疲劳损伤分别与专业海工计算软件OrcaFlex和已发表文献进行对比验证。进一步对陡波形立管在涡激振动下的疲劳损伤进行参数敏感性分析,结果表明:浮子段长度、浮力因子、弹性模量、海流速度、波浪高度对陡波形立管疲劳损伤均有较大影响,有望为陡波形立管的实际工程设计提供参考。     

Calculation of Wave Pressure and Pressure Spectrum for Perforate-Pipe Breakwater

Standing waves are formed due to the reflection when waves meet vertical wall,thereforestrong structures are needed to keep the wall stability under the serious wave attack.For the improvementof the working condition and increase of the stability of the wall,the lower reflecting breakwaters have at-tracted close attention Reports mostly from Japanese researchers are often concerned with the wall ofcaisson equipped with open windows.In this paper a kind of hollow-pipe perforated breakwater is exam-ined which waves may partially perforate into the harbour basin.The wave in front of the wall can onlyform partial standing wave and wave force is reduced obviously.And the theoretical calculation of waveforce and analysis of wave force spectrum are all derived.Comparison between the results from theoreticalcalculation and hydraulic modeling shows reasonable agreement.     

强潮高浊度海域坐底结构物稳定性分析

为满足强潮高浊度海域海底观测网布设需求,以潮动力强、泥沙浓度高的舟山群岛螺头水道为例,研究坐底结构物的稳定性。对3种形状的观测网坐底混凝土结构体进行计算分析,结果表明3种结构体抗滑安全系数2.22~7.40,抗倾覆安全系数1.59~1.64,沉降14.32~43.60 mm,地基承载力符合规范要求。针对冲刷可能导致的结构倾斜,建立结构体泥沙冲淤三维数值模型,分析了3种结构体的局部微流场与底床冲淤特性。模型结果表明,3种观测网坐底结构体在强潮流高浊度海域中符合稳定性要求,其中圆台结构体的稳定性最好。