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1.
High-pile and beam-slab quays have been widely used after several years development. They are mature enough to be one of the most important structural types of wharves in China coastal areas. In order to accommodate large tonnage vessels, wharves should be eorrstructed in deep water gradually. However, conventional high-pile and beam-slab structares are hard to meet the requirements of large deep-water wharf. According to arch＇ s stress characteristics, a new type of wharf with catenary arched longitudinal beams is presented in this paper. The new wharf structure can make full use of arch＇s overhead crossing and reinforced concrete compression resistance, improve the interval between transverse bents greatly, and decrease underwater construction quantity. Thus, the construction cost cab be reduced. Take the third phase project of the Yangshan Deep-water Port for example, comparative analysis on catenary arched longitudinal beams and conventional longitudinal beams has been made. The result shows that with the same wharf length and width, the same loads and same longitudinal beam moment, catenary arch structure can improve the interval between bents up to 28 m, decrease the nmnber of piles and underwater construction quantity. 相似文献
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在环境条件和使用荷载作用下,高桩码头结构损伤和承载力降低是普遍存在的问题。在役梁板式高桩码头结构安全评估,是保证港口设施安全运行的必要措施。结构整体可靠度是结构安全评估的核心指标,但目前尚未建立结构整体可靠度计算的有效方法。基于非线性有限元数值模型,采用蒙特卡罗模拟技术确定了典型梁板式高桩码头结构整体极限承载力概率分布模型及其统计参数,研究了损伤位置、损伤程度和损伤数量等对极限承载力概率分布及其统计参数的影响,明确了无损结构整体极限承载力概率分布模型及其统计参数可用于损伤结构分析。将结构整体极限承载力作为结构抗力随机变量,采用一次二阶矩法计算结构的可靠指标,建立了一种在役梁板式高桩码头结构整体可靠度计算的有效方法。 相似文献
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Blockley DJ 《Marine environmental research》2007,63(4):409-427
Worldwide, urbanisation has resulted in extensive replacement of natural habitats with man-made habitats. In Sydney Harbour, Australia, approximately half of the natural foreshore has been replaced by seawalls. Many of these have wharves built over part of their length, which could affect intertidal assemblages on seawalls beneath the wharves. This was tested by sampling and comparing assemblages under and not under wharves in Sydney Harbour. Assemblages differed between the two habitats, with greater cover of macro-algae and abundance of grazing molluscs on seawalls without a wharf and, to a lesser extent, greater cover of sessile invertebrates on seawalls under a wharf. There was, however, considerable spatial variability among locations in composition of assemblages and the species dominating differences between the two habitats. The impact of multiple artificial structures in close proximity and the variability among apparently homogeneous artificial habitats must be considered for the management of urbanised estuaries. 相似文献
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There has been a growing trend in the development of offshore deep-water ports in China. For such deep sea projects, all-vertical-piled wharves are suitable structures and generally located in open waters, greatly affected by wave action. Currently, no systematic studies or simplified numerical methods are available for deriving the dynamic characteristics and dynamic responses of all-vertical-piled wharves under wave cyclic loads. In this article, we compare the dynamic characteristics of an all-vertical-piled wharf with those of a traditional inshore high-piled wharf through numerical analysis; our research reveals that the vibration period of an all-vertical-piled wharf under cyclic loading is longer than that of an inshore high-piled wharf and is much closer to the period of the loading wave. Therefore, dynamic calculation and analysis should be conducted when designing and calculating the characteristics of an all-vertical-piled wharf. We establish a dynamic finite element model to examine the dynamic response of an all-vertical-piled wharf under wave cyclic loads and compare the results with those under wave equivalent static load; the comparison indicates that dynamic amplification of the structure is evident when the wave dynamic load effect is taken into account. Furthermore, a simplified dynamic numerical method for calculating the dynamic response of an all-vertical-piled wharf is established based on the P-Y curve. Compared with finite element analysis, the simplified method is more convenient to use and applicable to large structural deformation while considering the soil non-linearity. We confirmed that the simplified method has acceptable accuracy and can be used in engineering applications. 相似文献
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Combining high precision numerical analysis methods with optimization algorithms to make a systematic exploration of a design space has become an important topic in the modern design methods. During the design process of an underwater glider''s flying-wing structure, a surrogate model is introduced to decrease the computation time for a high precision analysis. By these means, the contradiction between precision and efficiency is solved effectively. Based on the parametric geometry modeling, mesh generation and computational fluid dynamics analysis, a surrogate model is constructed by adopting the design of experiment (DOE) theory to solve the multi-objects design optimization problem of the underwater glider. The procedure of a surrogate model construction is presented, and the Gaussian kernel function is specifically discussed. The Particle Swarm Optimization (PSO) algorithm is applied to hydrodynamic design optimization. The hydrodynamic performance of the optimized flying-wing structure underwater glider increases by 9.1%. 相似文献
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宁波北仑地区海域水文泥沙条件为：深水贴岸、港域受控于落潮流且掩护条件好、近岸水体含沙量高；港口建设中，码头走向应与主流向一致，码头与岸应以透空栈桥相连接。 相似文献
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厦门及临近地区桩式码头工程的若干地质问题 总被引：3，自引：0，他引：3
由于复杂的区域地质背景,使得本区存在着一些不利于桩式码头设计和施工的地质因素,如基岩民裂、工区内不同岩性相互交错、孤石和滚石等。本文总结了本区桩式码头工程地质勘察经验,对其存在的一些问题进行探讨,并对提高区域地质复杂地区桩式码头地质勘察的准确性提出一些看法。 相似文献
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Laboratory study of random wave slamming on a piled wharf with different shore connecting structures
《Coastal Engineering》2005,52(5):463-471
Impact pressures from random waves on the underside of a wharf deck were measured in a laboratory wave channel. Three different types of shore connecting structures were considered: open-piled, permeable slope and impermeable slope wharves. The experiments were carried out with significant wave heights ranging from 10 cm to 20 cm, spectral peak periods ranging from 1.0 s to 2.0 s, and the relative clearance of the model with respect to significant wave heights ranging from 0.1 to 0.4. The characteristics of the wave impact pressures for different shore connecting conditions are investigated, and their statistical distributions along the underside of the models are also determined. Experimental results indicate that the impact pressures depend on parameters such as the significant wave height, the spectral peak period, and the relative length and clearance of the model. 相似文献
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常规耐压结构拓扑优化设计研究主要集中于静水压条件下的设计相关载荷拓扑优化理论及方法。但是,在深海环境下,耐压结构可能面临内爆所产生的冲击载荷,其载荷呈现高频率的周期性变化。为研究载荷变化对耐压结构优化设计的影响,在BILE模型的基础上,结合修正的SIMP插值模型,开展不同频率、设计相关动载荷作用下的水下耐压结构拓扑优化理论及方法研究。设计相关动载荷的难点在于不仅载荷的作用位置和方向在优化过程中发生变化,且其大小也随优化过程进行而发生变化,这是与常规设计相关静载荷本质的不同。通过经典的拱形结构优化算例验证BILE模型在动力学拓扑优化中的可行性,进而研究设计相关动载荷作用下的水下耐压结构的最佳拓扑形式。研究表明,在低频时,圆环型耐压结构无明显变化,但多球交接耐压结构在交接处会出现明显材料聚集;高频时,两者均发生明显变化,得到耐压结构新形式。关于设计相关动载荷作用下的水下耐压结构拓扑优化研究,将对新型水下耐压结构的探索具有一定的工程应用价值。 相似文献
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介绍了基于CORS的网络RTK技术在水下测绘的应用及技术优势,并与常规测绘方法进行了比较分析.通过实例介绍了利用FJCORS进行的水下测绘应用及采用的CORS定位精度检测法,结果表明满足精度要求,验证了其在水下测绘的适用性. 相似文献
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The paper presents a conceptual design of an underwater missile launcher, which will be more difficult to detect by the enemy than conventional surface missile launchers which are currently being used.The paper suggests that the material of construction should be a composite and not a metal, as use of the latter for a large deep diving underwater vessel will result in such a structure sinking like a stone, due to the fact that it will have no reserve buoyancy. The paper also shows that composites have better sound absorption characteristics, thereby making the underwater structure difficult to detect through sonar equipment. It is proposed that this launcher should operate up to a depth of 5000 m, as at this depth, some 60% of the oceans' bottoms can be reached.The author shows that current technology can be used to construct and operate such a vessel. 相似文献
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A vector hydrophone is composed of two or three spatially collocated but orthogonally oriented velocity hydrophones plus an optional collocated pressure hydrophone. A vector hydrophone may form azimuth-elevation beams that are invariant with respect to the sources' frequencies, bandwidths and radial location (in near field as opposed to the far field). This paper characterizes the spatial matched filter beam patterns (a.k.a. fixed or conventional or maximum signal-to-noise ratio beam patterns) and the minimum variance distortionless response (MVDR) beam patterns associated with a single underwater acoustic vector hydrophone distant from any reflecting boundary. 相似文献
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海底影像存在着对比度低、噪声污染严重、图像质量差等问题，采用传统算子的海底管线边缘图像中含有大量的无用和断裂边缘信息。文中将多尺度边缘检测和匹配跟踪相结合，提出利用平稳小波变换的海底管线边缘检测方法；在提取边缘的同时利用匹配跟踪手段对噪声干扰进行抑制，提高图像目标边缘检测质量。通过对海底管线和测试图像边缘检测实验表明，文中所提出的方法在抑制图像噪声的干扰、提高水下目标边缘完整性方面明显优于传统的边缘提取算子，证明该算法的有效性。 相似文献
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海上风电场建设期风机打桩会产生高强度的水下噪声,研究水下冲击打桩噪声的监测方法、特性分析及对海洋生物的影响是非常重要的。采用自容式水下声音记录仪,多点同步测量了福建省兴化湾海上风电场二期工程建设期单次完整的水下冲击打桩噪声,从时频域特性进行了分析,并利用最小二乘法拟合得到了打桩声源级和声暴露级。结果表明：水下冲击打桩噪声是典型的低频、高强度的脉冲信号,单个脉冲持续时间约90~100 ms,峰值声源级约209.4±2 dB,声暴露级约197.7±2 dB;主要能量分布在50 Hz~1 kHz频段,750 m测量点的该频段声压级相比海洋环境背景噪声,提高了约40~50 dB。水下冲击打桩噪声频域能量分布与大黄鱼的听觉敏感频段相重叠,对大黄鱼影响程度和范围较大,实际工程应用中宜采用声暴露级作为评价指标。 相似文献
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根据1979,1996和2009年3个时期水深地形数据,利用GIS软件分析了岱山水道西部潮滩、水下岸坡和深槽区2个时段的冲淤变化。结果显示:1979-1996年的17 a间,研究区大部分区域冲淤幅度-般在±1 m以内,只有深槽局部区域冲刷大于2 m;1996-2009年的13 a间,潮滩区冲淤变化与1979-1996年间类似,有±1 m冲淤变化,而水下岸坡和深槽区的冲刷幅度明显加大,水下岸坡平均冲刷幅度达2 m,深槽区平均冲刷幅度达3 m。据分析, 1996年以后,水下岸坡和深槽区冲刷幅度明显加大的主要原因有两个:-是岱山水道水流流速较快,粘土质的底质容易遭受冲刷;另-个是在潮滩区至水下岸坡间建设了码头和栈桥,浅水区水流部分受阻,导致深水区域流速加大,从而加剧了水下岸坡和深槽区域的冲刷幅度。 相似文献
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位于马来盆地与西纳土纳盆地交汇处的研究区上新统?更新统发育复杂的浅海、海陆过渡相水下分支河道体系,常规的地震资料无法进行精细识别刻画。通过对叠后地震资料进行希尔伯特?黄变换,提取了地震资料高频分量,提高了地震资料的分辨率,有效识别了薄层砂泥岩交互特征和细微沉积体。通过对高频分量进行瞬时属性提取,明确了目的层段水下分支河道的平面展布特征。与常规叠后地震属性相比,经过希尔伯特?黄变换后的叠后地震资料提取的瞬时属性显示了更多沉积体系的细节特征,为水下分支河道的内部结构、发育期次、切割关系等时空演化研究提供了更高分辨率的地震数据。 相似文献
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针对海洋平台损伤检测方法中需要未损伤模型参数的不便，提出了一种相对频率变化量的方法。对不同类型构件的损伤及同一类型构件在不同位置损伤的情况，进行结构模态分析，研究平台结构的固有频率对损伤、损伤位置和损伤程度的敏感性，以及平台质量变化对频率的影响。利用两次测量的相对频率变化量，可以发现损伤的存在，并进行损伤的初步定位。 相似文献