共查询到19条相似文献，搜索用时 78 毫秒
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防波堤风险分析研究框架 总被引：1，自引：0，他引：1
介绍了防波堤风险分析研究的内容、方法和目前的研究进展。防波堤风险分析包涵四个主要方面:防波堤风险辨识、防波堤风险估计、防波堤风险评价和防波堤风险控制。具体内容包括:防波堤系统正常使用极限状态和承载力极限状态的界定,波浪不确定性的识别和描述,防波堤失效模式的探讨,单一模式失效概率和系统失效概率的计算,两种极限状态失效后果的量化,成本-获益分析,效用分析,可接受风险准则和降低风险的措施。防波堤风险分析的目的在于为决策者明确工程中存在的诸多不确定性因素,提供充足信息,实现项目的决策优化。 相似文献
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防波堤是港工建筑物中的一个重要组成部分,主要作用为保护港湾免受波浪、冰、沙等海洋动力因素的侵袭.综合以往的相关文献,对于防波堤断面破坏形式,如滑移、倾覆、地基滑动等有了非常充分的研究,可以定量计算出其损坏程度.而对于防波堤平面形态的损坏,如蛇行破坏等,只是较深入研究了失效机理,并没有一个能够定量计算其后果的模型.本文第一部分将期望滑移量模型和绕射模型结合,建立了计算半无限长沉箱式防波堤在使用期限内蛇行破坏程度的模型.第二部分则利用实测的波浪数据设计并计算了一个沉箱式防波堤实例.结果表明,各个堤段的期望滑移量呈现出一定周期性变化的规律,堤头附近区域的滑移量远大于较远的堤段,这对于防波堤施工过程中的堤头防护具有参考价值.本文为建立防波堤平面形态损坏定量计算模型提供了一种思路. 相似文献
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波浪作用下方箱-水平板浮式防波堤时域水动力分析 总被引：1，自引：0，他引：1
在线性化势流理论范围内求解方箱-水平板浮式防波堤的波浪绕射和辐射问题,从时域角度分析了浮式防波堤的水动力特性.采用格林函数法将速度势定解问题的控制微分方程变换成边界上的积分方程进行数值求解,浮式防波堤的运动方程采用四阶Runge-Kutta方法求解.对不同层数水平板的浮式防波堤的波浪透射系数、运动响应和锚链受力进行了计算分析,结果表明方箱相对宽度对方箱-水平板浮式防波堤的波浪透射作用有重要的影响,透射系数随着方箱相对宽度的增加而减小.对于方箱加二层水平板的浮式防波堤,在本研究的计算条件下,当方箱相对宽度从0.110增加至0.295时,透射系数从0.88减小至0.30.水平板有利于增加浮式防波堤对波浪的衰减作用,但随着水平板层数从0增加至2,这种波浪衰减作用增加的程度趋弱.方箱-水平板的浮式防波堤的运动量小于单一方箱防波堤的运动量.与此对应,方箱-水平板防波堤的锚链受力小于单一方箱防波堤的锚链受力. 相似文献
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防波堤建设费用巨大,且一旦遭到破坏,后果甚为严重,因此,如何准确地计算防波堤的可靠性意义重大.随着人工神经网络理论的快速发展,人工神经网络方法在结构可靠性分析中的应用逐渐得到重视.基于神经网络的Monte Carlo法计算直立式防波堤的可靠性,概率意义明确.以秦皇岛典型直立堤为算例,采用基于神经网络的Monte Carlo法对直立式防波堤进行可靠性分析时,将直立堤滑动破坏和倾覆破坏的极限状态方程中的所有参数均作为变量处理,并将计算结果与Monte Carlo模拟的直接抽样法、重要抽样法以及独立变量JC法的计算结果进行对比.结果表明:基于神经网络的Monte Carlo法和Monte Carlo模拟的直接抽样法、重要抽样法计算结果相近,而比独立变量JC法的计算结果略低. 相似文献
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日本电力会社、中央研究所,研究成功两种新型,既降低建没费用,又提高性能的防波堤。今后在建设防波堤时,将采用其中的某一种。新型防波堤,是用混疑土预制的箱型结构,但与消波砌外型的防波堤不同。迄今的防波堤,上边是平面的。造价高,易磨耗,越波防止机能差。新型防波堤有两类。一是缝隙型,二是缓斜面型。 相似文献
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以南海某平台组块海上拖航作业为例,阐述风险评估的基本流程;针对海上拖航过程提出一套具体、实用的风险辨识、事故树建立以及建立风险控制措施的方案;同时给出一种将风险因素定性计算予以量化的方法,即风险值计算方法,并且针对海油工程确定风险值标准. 相似文献
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将信息论中的熵值理论与层次分析法相结合,兼顾决策者主观偏好与方案的客观属性,采用多种目标函数建立优化模型,将熵权与主观权重结合以确定综合权重,给出了多种交互式多目标决策模型。以某港新建工程的多种设计方案的排序优选为例,比较分析了新模型与层次分析法的计算结果,说明新模型在港口规划方案优选时更易反映多种主观与客观因素对方案决策的影响,结果更加合理。 相似文献
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工程风险分析中的风险当量及其评价标准 总被引：7，自引：2，他引：7
目前，量化、半量化风险分析是工程风险分析的主流。在对工程进行量化和半量化风险分析时，无论采用什么方法，风险评价指标和评价标准都是关键的重要问题。只有在建立了统一的评价指标和评价标准体系的基础上，对工程进行的风险分析能够得出正确和一致的结论。文章通过对国内外风险分析理论和实践的研究和总结，提出了在工程风险分析中确定风险评价指标和评价标准的原则和方法。 相似文献
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针对海工作业平台、海洋养殖网箱等海洋装备的安全防护问题，提出了一种带空气透平的后弯管浮式防波堤，该空气透平既可将作用在防波堤上的波浪能转化成机械能并用于发电，还可显著减小防波堤的锚链力。在介绍了防波堤原理和结构特点的基础上，设计了物理实验模型，并在实验室造波池内进行了模型试验，研究了波浪周期、波高、吃水深度与弯管数量等因素对后弯管浮式防波堤透射系数和锚链力的影响规律。研究结果表明，波浪周期越短，波高越低，防波堤的透射系数越小，锚
链力越小，其消波性能优于传统的浮式防波堤. 相似文献
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Based on the idea of disturbing the water motion in the upright direction, a new kind of multiple-layer breakwater is proposed in this article, which mainly consists of several horizontal plates. The breakwater's performance of dissipating waves has been investigated in detail in the regular wave tests. The factors identified with the characteristics of the breakwater are discussed, such as the relative width, the wave steepness and the models geometrical parameters (the width and the gap). The comparison and analysis of the transmission and reflection coefficients with respect to different factors are presented. The model test results indicate that the multiple-layer breakwater has the good characteristic of dissipating waves. Further more, only in a little extent can it reflect the waves. The multiple-layer breakwater proposed in the paper is very significative to promote the open type breakwater to be the permanent wave attenuator in the application. 相似文献
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《Applied Ocean Research》2005,27(4-5):187-208
In the present paper, the performance of a moored floating breakwater under the action of normal incident waves is investigated in the frequency domain. A three-dimensional hydrodynamic model of the floating body is coupled with a static and dynamic model of the mooring lines, using an iterative procedure. The stiffness coefficients of the mooring lines in six degrees of freedom of the floating breakwater are derived based on the differential changes of mooring lines' tensions caused by the static motions of the floating body. The model of the moored floating system is compared with experimental and numerical results of other investigators. An extensive parametric study is performed to investigate the effect of different configurations (length of mooring lines and draft) on the performance of the moored floating breakwater. The draft of the floating breakwater is changed through the appropriate modification of mooring lines' length. Numerical results demonstrate the effects of the wave characteristics and mooring lines' conditions (slack-taut). The existence of ‘optimum’ configuration of the moored floating breakwater in terms of wave elevation coefficients and mooring lines' forces is clearly demonstrated, through a decision framework. 相似文献
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Babloo Chaudhary Hemanta Hazarika Siavash Manafi Khajeh Pasha 《Marine Georesources & Geotechnology》2018,36(3):308-322
Coastal protective structures, such as composite breakwaters, are generally vulnerable to earthquake. It was observed that breakwaters damage mainly due to failure of their foundations. However, the seismically induced failure process of breakwater foundation has not been well understood. This study describes failure mechanism of breakwater foundation as well as a newly developed reinforcing model for breakwater foundation that can render resiliency to breakwater against earthquake-related disasters. Steel sheet piles and gabions were used as reinforcing materials for foundation. The experimental program consisted of a series of shaking table tests for conventional and reinforced foundation of breakwater. Numerical analyses were conducted using finite difference method, and it was observed that the numerical models were capable to elucidate the seismic behavior of soil–reinforcement–breakwater system. This paper presents an overview of the results of experimental and numerical studies of the seismic response of breakwater foundation. Overall, the results of these studies show the effectiveness of the reinforced foundation in mitigating the earthquake-induced damage to the breakwater. Moreover, numerical simulation was used for parametric study to determine the effect of different embedment depths of sheet piles on the performance of breakwater foundation subjected to seismic loading. 相似文献
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弧板式透空堤消浪性能影响因素数值研究 总被引：1，自引：0，他引：1
弧板式透空堤是由弧型板组成的新型防波堤结构。为探讨其透射系数的影响因素,利用Fluent软件基于N-S方程构建了波浪与板式透空堤相互作用的数值模型,讨论了相对潜深、入射波周期、相对波高、相对板宽和结构型式对透射系数的影响。结果表明:弧板式透空堤的透射系数随着相对波高和入射波周期的增大而增大,在静水面附近透射系数最小,尤以静水面和略高于静水面时的消浪效果最佳;在相同波浪要素条件下,静水面及其上0.02 m和0.04 m位置处,弧板式透空堤的消浪效果明显优于平板式透空堤。 相似文献
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基于水槽实验,研究植物对孤立波作用下直立堤局部冲刷的影响。通过改变实验入射波高、植物带的宽度和密度,分析各要素对直立堤局部冲刷的影响。实验对波高沿程变化、孤立波越堤、回落过程以及地形演变进行全程的测量和记录,并进行有无植物带保护的直立堤局部冲刷对比分析。结果表明,植物带的存在,使得堤后相对最大冲刷深度显著减小,堤前冲刷形态由单峰式"L"型变为双峰式淤积沙坝形态,且冲刷位置由原堤脚前移至植物带所在位置,冲刷范围大幅增加。减小植物带密度或者植物带宽度会使近岸侧或是离岸侧的相对最大冲刷深度和相对最大淤积高度有增大的趋势,但是当入射波高增大时,二者的影响不显著。该研究对实际工程中植物带的合理布置提出了具有参考性的建议,对减少堤防工程的冲刷和损失有一定现实意义。 相似文献
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The present study investigated how the perforations, water depth and rubble mound height on fully perforated semicircular breakwater (SBW) affects non-breaking wave transformations. SBW model with surface piercing condition for three different perforation ratios with 7 percentage, 11 percentage and 17 percentage were considered to study the variation of reflection, transmission, run-up characteristics and dimensionless horizontal and vertical forces as a function of relative water depth and the results are compared with an impermeable SBW and seaside perforated SBW models. From the results it is understood that, SBW with perforation ratio 17 percentage in the case of seaside perforated case shows reverse trend in hydrodynamic characteristics and for fully perforated SBW, it transmits large amount of wave energy on the seaside, which affects the tranquillity condition in the harbour. In addition, transmission characteristics of SBW models and conventional rubble mound breakwater model are compared to understand the effect of composite breakwater action and also the reflection characteristics of SBW models are compared with field data of Miyazaki Port after Sasajima et al. (1994). The results reveal that the SBW model with perforation ratio of 11 percentage in seaside and fully perforated type gives an optimum performance in terms of energy dissipation and transmission. 相似文献
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