共查询到19条相似文献,搜索用时 78 毫秒
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大型船闸人字闸门因门体较高、启闭时雍水阻力及风阻力较大,背拉杆大多采用预应力结构。为延长其顶底枢的使用寿命,常在最低通航水位以下设置浮箱。结合下坝复线船闸,先介绍预应力背拉杆及浮箱的布置形式,再着重引入美国陆军工程师兵团SHERMER C L提出的理论进行设计计算,最后对有浮箱结构的人字闸门背拉杆预应力施加方法进行探讨。 相似文献
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<正>船舶浮箱结构是指以钢结构形式建造的、贴附在船壳外表的箱式结构,主要的作用是增加额外浮力、增加排水量或用来调整船舶艉倾值过大。常规新建项目一般对于整个船体的稳性状态有较好的计算和控制,极少采用该类结构形式。但在船舶改装过程中,尤其是重大改装过程中,可能会出现因新增的结构和设备的重量过大导致整体稳性浮力缺失、艉倾过大的问题。本文通过某型改装船新增边浮箱结构的具体案例,对此类浮箱结构设计要求及建造、搭载工艺方案进行介绍。 相似文献
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针对新型双浮箱-双水平板防波堤,应用Ansys Workbench软件和AQWA Graphical Supervisor (AGS)图像后处理软件,建立三维数值模型,研究浮箱的相对吃水深度、浮箱的相对间距和相对板间距对消波效果的影响以及自身稳定性分析。结果表明:增大浮箱的吃水深度和相对板间距,可以减小防波堤的透射系数;取浮箱相对间距为0.22~0.33时,有更好的消波效果;双浮箱-双水平板浮式防波堤的固有周期大约为5 s,实际应用中应避免固有周期与波浪周期相近。研究结果可以为该型防波堤的设计提供理论基础。 相似文献
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脐带缆深水安装的参数影响分析(英文) 总被引:1,自引:0,他引:1
随着水深的增加引起外部压力的增大和脐带缆的重量相应增加,且由于海洋环境载荷和浮体的运动引起复杂的动力特性使得脐带缆的受力复杂,其安全性受到很大的挑战,故深水安装是脐带缆的关键问题之一。文章详细分析了安装过程中不同浮力块的布置方式(不同尺寸,长度和布置位置)和波浪与流的方向对脐带缆的影响。利用悬链线方程构建自由悬挂的脐带缆的模型,然后施加浮力与环境载荷得到动态脐带缆的安装模型。通过对比分析表明,浮力块的布置方案和波浪与流的方向对脐带缆的安装都有很大的影响,上述这些参数在安装中需要给予重视。 相似文献
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J.H. Simpson 《Journal of Marine Systems》1997,12(1-4)
The distinctive feature of all ROFI (Regions Of Freshwater Influence) systems is the input of significant amounts of buoyancy as freshwater from river sources. If the spatial scale is unrestricted by coastal topography and stirring is weak, this input tends to drive a coast-parallel flow in which the Coriolis force constrains a wedge of low density water against the coastal boundary. Without frictional effects, this flow is subject to baroclinic instability which induces large meanders and eddies in the flow but in, many ROFIs, the tidal flow induces frictional effects which stabilise the density driven flow.In the absence of the effects of rotation and stirring, the buoyancy input tends to induce stratification through an estuarine circulation in the direction of the gradient. When stirring is applied, by the action of wind, waves or tidal flow, the density current is suppressed but is rapidly re-established when stirring ceases, as in the Linden-Simpson (1988) laboratory tank experiments. In real ROFI systems, a combination of all these processes operates so that the structure of the water column and the flow is the result of a competition between the stratifying influence of buoyancy input and the net stirring effect of the wind, waves and the tides. This competition is more difficult to analyse than the heating-stirring competition, because freshwater buoyancy input is not spatially uniform but enters at discrete sources along the coast and its subsequent spreading has to be determined.While the springs-neaps cycle in tidal stirring imposes a regular fortnightly modulation on vertical mixing, the influence of the wind is irregular and depends, not just on the magnitude of the stress, but also on the direction in which it acts. In some exposed shallow water situations there may also be significant stirring due to waves generated by non-local winds.ROFI systems are further complicated by the action of tidal straining in which differential advection, due to vertical shear in the tide, interacts with the density gradient to generate fluctuations in vertical stability at the tidal frequency which, in some cases, are of sufficient amplitude to switch the water column between stable stratification and vertical density homogeneity each tidal cycle. This straining along with the other ROFI processes have been incorporated into a series of 1-D models to provide a more objective test of the hypotheses about the mechanisms involved. Comparison of model hindcasts with observations indicate that we now have a first-order understanding of the complex behaviour of ROFIs.On a global scale it is clear that ROFIs represent an important component of the shelf-sea environment of particular concern in relation to the impact of pollutant discharges. To date, most studies of ROFI's have concentrated on systems in temperate latitudes but attention needs to be focused on the very extensive ROFIs in tropical regions where most of the world's river discharge enters the ocean. In monsoonal regions, these inputs exhibit strong seasonal modulation which may, in competition with tidal stirring, result in an annual cycle of stratification and the formation of fronts. 相似文献