共查询到20条相似文献，搜索用时 24 毫秒
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1 .IntroductionWiththedevelopmentofexploitationofmarineresources ,theconstructionofoffshorestructuresdevelopsrapidly ,suchasmarineoilplatforms ,deep waterbreakwaters ,marinebridges ,largehar bors,etc .Thesestructureswillchangesurroundingwaveandcurrentconditionsandleadtolocalscourofseabed ,resultinginstructuraldamage .Therefore ,localscouraroundmarinestructuresaswellastheirprotectionhasdrawnmuchattentionfromrelativeengineeringfields .Manyscholarshaveconduct edtheoreticalanalysisandexperimentals… 相似文献
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海啸作为世界上最严重的自然灾害之一,其巨大的破坏力使得近海建筑物遭受了严重的损害。基于波浪水槽实验,开展海啸波作用下不同口门距离的防波堤局部冲刷机理实验研究。实验结果表明,在海啸波越顶水流产生的水跌以及海啸波通过防波堤口门时产生的扰流共同作用下,口门中心线处产生明显的局部冲刷坑,随着口门距离的增加,防波堤局部冲刷先加剧后减弱。建立防波堤局部最大冲刷深度与海啸波波高、防波堤宽度及出水高度、口门间距的关系式,揭示了最大局部冲刷深度与海啸波波高、防波堤尺寸、口门距离的内在关系。 相似文献
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桥墩基础冲刷是桥梁毁坏的重要因素,是桥梁基础设计的关键指标之一。目前国内外对于桥墩基础在复杂动力条件下冲刷深度的研究常采用物理模型试验方法,利用正态系列模型方法,在波流水槽中研究了水流、潮流和波流共同作用下青州航道桥索塔基础周围流态变化和局部冲刷特征。研究结果表明,桥墩最大冲刷深度和冲淤范围与水流流速、桥墩轴线与水流夹角和波浪等因素有关;在潮流最大流速和恒定流流速一致情况下,桥墩局部冲刷深度达到平衡后,将会达到与恒定流基本一致的最大冲深;波流共同作用下的最大冲刷深度比恒定流增加10%左右。设计桥墩形状在100年一遇水流和波浪共同作用下桥墩基础局部最大冲刷深度为13.7 m。 相似文献
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波浪作用下大尺径圆柱周围局部冲刷 总被引：3，自引：0，他引：3
通过系列模型试验，对波浪作用下墩柱周围局部冲刷地形及其形成机理进行了分析，认为最大冲刷深度发生在墩柱前方，与防波堤前冲淤形态类似，分为细沙型和粗沙型。在对各影响因子分析基础上，提出墩柱周围最大冲刷深度计算公式，试验资料表明，该公式与试验值有着良好的一致性。 相似文献
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波浪作用下桶形基础冲刷特性试验研究 总被引：1，自引：1，他引：0
在设计结构和考虑有效的海洋工程基础的冲刷防护工程时,了解和预测海洋结构周围的冲刷发展机理是非常重要的。通过波流水槽研究规则波作用下桶形基础的冲刷特性,试验主要考虑波高与结构尺寸对桶形基础周围局部冲刷的影响,并分析波浪冲刷过程中模型周围的时程地形、波浪作用后的冲刷坑性状、冲刷影响要素以及不同结构间的冲刷差异。结果表明:桶形基础的冲刷过程是震荡加深发展,最大冲刷深度与冲刷宽度随波高增大而增加,随上部结构直径增大而增加,最大冲刷深度位置随波高与结构尺寸变化而变化;不同结构间的冲刷坑形态与冲刷后的地形不同,最大冲刷深度相差可高达4倍;桶形基础结构直径比范围为0.2～0.5时,结构自身具有防冲刷能力。 相似文献
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Understanding the sediment transport and the resulting scour around coastal structures such as pile breakwaters under local extreme wave conditions is important for the foundation safety of various coastal structures. This study reports a wave-flume experiment investigating the scour induced by solitary waves at a pile breakwater, which consists of a row of closely spaced large piles. A wave blacking gate with a simple operation procedure in the experiment was designed to eliminate possible multiple reflections of the solitary wave inside the flume. An underwater laser scanner and a point probe were used in combination to provide high-resolution data of the bed profile around the pile breakwater. Effects of incident wave height and local water depth on the maximum scour depth, the maximum deposition height and the total scour and deposition volumes were examined. An existing empirical formula describing the evolution of the scour at a single pile in current or waves was extended to describe the scour at the pile breakwater under the action of multiple solitary waves, and new empirical coefficients were obtained by fitting the formula to the new experimental data to estimate the equilibrium scour depth. It appears that the maximum scour depth and the total scour volume are two reliable quantities for validation of numerical models developed for the scour around pile breakwaters under highly nonlinear wave conditions. 相似文献
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要研究波流共同作用下桩墩的基础冲刷问题,首先需要了解水流和波浪单独作用下桩墩冲刷的机理和特征。针对波、流及其共同作用下桩墩的局部冲刷问题,从流速、水深、桩径、波长、波高、相对底层流速、粒径和粒径级配等方面系统地简述了恒定流、波浪和波流作用下桩、墩局部冲刷的研究进展。根据实验资料比较了各家经典计算公式的计算结果发现我国规范65-1式计算值偏大,65-2式计算值偏小等结论。桩墩局部冲刷是一个复杂的过程,今后可以针对淤泥质海岸底床、粉沙质海岸底床、复杂桩群结构、物理模型比尺效应、非恒定水动力条件、复杂基础形式方面对波流作用下基础冲刷的最大冲刷深度、冲刷过程、冲刷范围进行研究,以弥补桩墩局部冲刷在这些方面的不足。 相似文献
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This paper presents the results of an experimental investigation on three-dimensional local scour below a rigid pipeline subjected to wave only and combined wave and current conditions. The tests were conducted in a conventional wave flume. The major emphasis of the investigation was on the scour propagation speed (free span expansion rate) along the pipeline after local scour was initiated at a controlled location. The effects of flow ratio (steady current velocity vs. combined waves/current velocity), flow incidence angle and pipeline initial embedment depth on free span expansion rate were investigated. It was observed that the scour along the pipeline propagated at a constant rate under wave only conditions. The scour propagation rate decreased with increasing embedment depth, however, increased with the increasing Keuglegan–Carpenter (KC) number. Under combined wave and current conditions, the effect of velocity ratio on scour propagation velocity along the pipeline was quantified. Empirical relationships between the scour propagation rate (Vh) and key parameters such as the KC number and embedment depth (e/D) were established based on the testing results. 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 purpose of this study is to investigate the characteristics of parameters for local scour depth around submarine pipes due to waves. Because it is impossible to consider all the factors that influence the scour, it is reasonable to investigate the correlations between parameters and scour. The experimental works about scour were performed for the conditions of 40, 60, 90 m pipe diameter, various wave periods, and wave height in the case of horizontal bed and 1/10 slope bed, respectively. Analyzing the results of experiments, the Reynolds number, Shields parameter, Keulegan-Carpenter number, Ursell number, and Modified Ursell number were estimated. The correlations between the relative scour depth, which is the maximum equilibrium local scour depth divided by the pipe diameter, and 5 parameters were analyzed. It was shown that there was hardly any correlation with the Reynolds number. In the case of a horizontal bed, the Keulegan-Carpent number had the highest correlation, but in the case of the slope bed the correlation was greatly reduced. The modified Ursell number showed a high correlation regardless of the type of bed. 相似文献
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由于海床起伏不平,斜坡的存在必然改变波浪对管线及海床的作用特性,进而影响管线三维冲刷。基于波浪港池实验,考虑规则波的作用,采用中值粒径为0.22mm的原型沙铺设与波浪传播方向成45°夹角的斜坡,研究斜向波作用下斜坡上海底管线的三维冲刷特性。通过测量管线下方冲刷坑宽度和深度的差异,分析管线三维冲刷的不均衡性。实验表明:管线的存在使斜坡上的波高有所降低;斜向波作用下管线三维冲刷的不均衡性表现为深度不均衡性和宽度不均衡性,宽度不均衡性主要是管后淤积泥沙的后移引起的,周期对三维冲刷不均衡性的影响比波高对其的影响程度大;管线自深海向近岸延展时,随水深的减小,冲刷深度分为缓慢发展阶段和快速发展阶段。 相似文献
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Submarine pipelines are widely used coastal structures, and scour around them can influence their stability. In this study, scour around rigid submarine pipelines under normal-incidence irregular wave attack on horizontal and (1/10) sloping beaches is studied. This paper presents experimental results concerning scour under irregular wave attack. Multiple regression analysis is used to develop models to predict the scour depth under pipelines under the influence of irregular wave attack. The representative wave parameters that characterize the irregular sea state that causes the same scour depth as regular wave attack were determined. 相似文献
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为减轻海上风电单桩基础周围局部冲刷对其结构安全的影响,提出了一种新型旋转减冲装置。在波流水槽中开展物理模型试验,改变波流条件、装置安装高度、安装距离,记录桩周冲刷发展历时,运用激光地形仪扫描冲刷坑形态,分析各工况下冲刷坑形态差异,验证装置不同安装距离、安装高度下的冲刷防护效果,提出了不同安装位置下的防护效率公式。结果表明：新型旋转减冲装置具有较好的冲刷防护效果,本试验工况下,桩周最大冲刷深度可减小44%左右。装置安装距离对冲刷防护效果影响较小,波流作用下的冲刷防护效果受装置安装高度影响显著,冲刷防护效果随装置安装高度的增加而减弱。 相似文献
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海流作用下海底管道局部冲刷数值分析 总被引：1，自引：0，他引：1
在任意拉格朗日-欧拉参考坐标系下,采用基于雷诺平均的Navier-Stokes方程组(RANS)、流线迎风有限元方法、泥沙输运模型以及底床变形方程,对海流引起的海底管道局部冲刷进行了数值模拟。着重讨论了均匀来流流速和海底管道直径对局部冲刷发展过程及平衡冲刷深度的影响作用。数值结果表明,在冲刷的初始阶段,冲刷深度随时间迅速增加,之后缓慢逼近极限平衡深度;在管径一定的情况下,管道附近的局部平衡冲刷深度与流速大致呈线性关系;当流速超过某一临界区域后,最大平衡冲刷深度出现的位置并不在管道正下方,而是随流速的增加向管道下游方向移动;另外,管道直径也会对平衡冲刷深度产生比较明显的影响,在相同流速下,平衡冲刷深度大致随管径呈线性增大。在本文的计算范围内,海底管道的相对局部平衡冲刷深度基本随雷诺数线性增加,但流速对冲刷深度的影响作用要比管径的影响作用更为明显。 相似文献
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桩柱周围海底冲刷深度计算及动力参数的选取 总被引：1，自引：0，他引：1
通过６０年代以来研究的桩柱周围海底冲刷深度计算模式的对比分析表明,我国学者王汝凯等人提出的“普遍冲刷深度”、“局部冲刷深度”和“总冲刷深度”的计算模式在科研和生产实践中是可行的,能给设计和施工提供科学的和有价值的参数。各种冲刷深度的计算模式如下：普遍冲刷深度ｌｇ（Ｓｕ０／ｎ＋０．０５）＝－０．６６３＋０．３６４９ｌｇα（１）局部冲刷深度ｌｇ（Ｓｕ１／ｈ）＝－１．２９３５＋０．１９１７ｌｇβ（２）总 相似文献
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为了验证新型伞式吸力锚基础的防冲刷效果,本文利用Flow-3D软件建立三维海床-吸力锚-波浪相互作用模型,基于JONSWAP随机波浪谱,结合某海域风区资料模拟随机波,对随机波浪作用下伞式吸力锚基础(USAF)局部冲刷演变进行分析,试验土体为非黏性土.首先探讨了随机波浪作用下基础周围流场变化规律和冲刷演变模式,其次分析了... 相似文献
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An accurate estimation of scour depth around piles is important for coastal and ocean engineers involved in the design of marine structures. Owing to the complexity of the problem, most conventional approaches are often unable to provide sufficiently accurate results. In this paper, an alternative attempt is made herein to develop adaptive neuro-fuzzy inference system (ANFIS) models for predicting scour depth as well as scour width for a group of piles supporting a pier. The ANFIS model provides the system identification and interpretability of the fuzzy models and the learning capability of neural networks in a single system. Two combinations of input data were used in the analyses to predict scour depth: the first input combination involves dimensional parameters such as wave height, wave period, and water depth, while the second combination contains nondimensional numbers including the Reynolds number, the Keulegan–Carpenter number, the Shields parameter and the sediment number. The test results show that ANFIS performs better than the existing empirical formulae. The ANFIS predicts scour depth better when it is trained with the original (dimensional) rather than the nondimensional data. The depth of scour was predicted more accurately than its width. A sensitivity analysis showed that scour depth is governed mainly by the Keulegan–Carpenter number, and wave height has a greater influence on scour depth than the other independent parameters. 相似文献
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Pile groups are frequently used to support bridge decks. Scour in the vicinity of piles is the main cause for the bridges failure. In this research, to address the effects of uniform and nonuniform pile spacing on the equilibrium scour depth, laboratory experiments were carried out under steady clear-water conditions. For this purpose, scour depth produced by pile group with various pile spacing and arrangement was investigated using a laboratory flume. Flume bed was covered by uniform sediments with a median size of 0.9?mm and 0.2?m thickness. Flow discharge and velocity as well as scour depth were recorded in each experiment and the data were analyzed. The results showed that the pile spacing influences the local scour depth and with increase in uniform and transverse (perpendicular to the flow) spacing, the maximum scour depth was reduced. The pile spacing variation in line with the flow has a minor effect on scour depth. In addition, the pile spacing perpendicular to the flow was with the most influences on scour depth. The results of this research can be used by engineers to optimize the design of bridges. 相似文献
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长江口深水航道整治一期工程南导提丁坝群头局部冲刷试验研究 总被引：1，自引：1，他引：1
采用双向稳定水流、清水定床、局部动床的试验方法，用正态模型研究长江口深水航道整治一期工程南导堤丁坝群坝头局部冲刷问题。结果表明，航道开挖和双本坝的存在使得下游流速有所增加，影响程度落潮大于涨潮。坝头局部冲刷主要受落潮流控制，在沿深度为单一砂粉底质情况下，坝头冲刷坑深度分别达到27m和29m；考虑到原状底质下部为极难起动的粘土，实际冲刷坑底界到达粘土层后就不再刷深，此时冲刷坑深度为7．4m和4．7m，冲刷坑的平面范围有所加大。工程设计提出的护坦尺度能较好地保护坝头前沿滩地，适当缩小护坦尺度也能起到保护作用，但冲刷范围明显增大。 相似文献