Experimental Investigation of Irregular Wave Uplift Force on Deck of Exposed High-Pile Jetties

A laboratory setup was developed to investigate irregular wave uplift loads on exposed high-pile jetties. It is shown that the dimensionless uplift load increases to the maximum with an increasing relative clearance and then decreases. The relative clearance corresponding to the peak force is linked to a range from 0.4 to 0.8. When the relative clearance exceeds a certain value, the wave can not reach the underside of the deck and the force becomes zero. Distinct trends of dimensionless force with a relative width of deck show that the force tends to decrease as the relative deck width increases, and then the decrease slows down after the relative deck width increases or decreases to a certain value. The pressure distribution length associated with the maximum uplift force is equivalent to the wave contact width x. When x is larger than the width of deck B, it is taken as B. The statistical distribution of loads obeys the Weibull distribution. The results from the analyses of the real data suggest a new dimensionless prediction model on wave-in-deck uplift loads and the conversion ratio between wave loads at different exceedance probabilities. A comparison is made between the new prediction model and the existing widely used three prediction models. These results are used as useful references for structural design of the jetty.

A Method for the Damage Detection of Pile Foundation in High-Pile Wharf Based on A Curvature Mode Deletion Model

As the top of the pile foundation in high-pile wharf is connected to the superstructure and most of the pile bodies are located below the water surface, traditional damage detection methods are greatly limited in their application to pile foundation in service. In the present study, a new method for pile foundation damage detection is developed based on the curve shape of the curvature mode difference(CMD) before and after damage. In the method, the influence at each node on the overall CMD curve shape is analyzed through a data deletion model, statistical characteristic indexes are established to reflect the difference between damaged and undamaged units, and structural damage is accurately detected. The effectiveness and robustness of the method are verified by a finite element model(FEM) of high-pile wharf under different damage conditions and different intensities of Gaussian white noise. The applicability of the method is then experimentally validated by a physical model of high-pile wharf. Both the FEM and the experimental results show that the method is capable of detecting pile foundation damage in noisy curvature mode and has strong application potential.

The Research on Safety Evaluation of High-pile Wharf Structure

Due to a combination of the sea erosion,the ship collision,the change of ground condition,the effect of alternative static and dynamic load and the material deterioration,the structure of high-pile wharf is easily damaged.Once the structure of high-pile wharf destroyed,it is bound to be a great threat to the safety of various facilities and personnel in the port.Given all of that,the multi-level comprehensive evaluation method based on the extension theory is proposed in this paper.Using this method to assess the safety of high-pile wharf structure,the reasonable advice on its maintenance and reinforcement can be given in time.What’s more,the method is simple and can give more objective result of the evaluation.

Application of Converted Displacement for Modal Parameter Identification of Offshore Wind Turbines with High-Pile Foundation

In the actual measurement of offshore wind turbines(OWTs),the measured accelerations usually contain a large amount of noise due to the complex and harsh marine environment,which is not conducive to the identification of structural modal parameters.For OWTs with remarkably low structural modal frequencies,displacements can effectively suppress the high-frequency vibration noise and amplify the low-frequency vibration of the structure.However,finding a reference point to measure structural displacements at sea is difficult.Therefore,only a few studies on the use of dynamic displacements to identify the modal parameters of OWTs with high-pile foundations are available.Hence,this paper develops a displacement conversion strategy to study the modal parameter identification of OWTs with high-pile foundations.The developed strategy can be divided into the following three parts:zero-order correction of measured acceleration,high-pass filtering by the Butterworth polynomial,and modal parameter identification using the calculated displacement.The superiority of the proposed strategy is verified by analyzing a numerical OWT with a high-pile foundation and the measured accelerations from an OWT with a high-pile foundation.The results show that for OWTs with high-pile foundations dominated by low frequencies,the developed strategy of converting accelerations into displacements and then performing modal parameter identification is advantageous to the identification of modal parameters,and the results have high accuracy.

Android平台i-Jetty服务器在智能家居中的应用研究

针对智能家居系统架构复杂、开发难度较大等问题,提出了一种基于Android平台嵌入式Web服务器i-Jetty的智能家居系统方案。在ARM硬件平台及Android软件平台上,采用i-Jetty服务器实现了家居环境信息网络远程监控功能。系统以Mini6410开发板为中央控制器、服务器和室内监控平台,采用蓝牙与被控设备进行通信,通过Linux层驱动加载、Android本地服务和Web服务的联合编程,实现对传感器数据的获取、家电控制和信息发布。实验结果证明了方案的可行性和实用性。

海外石化码头项目装卸设施多层布置方案

针对国外石化码头平台相对于国内码头占地面积较大、设施拥挤严重的问题,提出一种新型装卸工艺设施布置方案,即码头结构采用双层设计,上层为日常操作平台,下层为靠泊系缆平台。在此基础上,装卸工艺设施分3层布置,其中需要日常操作的工艺设施布置在上层平台,辅助管道设施及电仪桥架悬挂在首层平台下,残液罐及废水收集池布置在下层平台。以东南亚某化工码头项目为例,介绍该布置方案的运用,并采用BIM技术创建码头装船工艺设施模型,进行装卸臂、登船梯的兼容性分析及相互间操作干涉分析,以提高码头操作可靠性及安全性。设计方案可显著优化装船平台布置,平台占用率降低40%,为运营操作、检修及改扩建提升了空间。同时,BIM技术用于船岸兼容性分析可避免装卸操作潜在的风险。

离岸油码头海底管线测漏系统方案设计及应用

海底油气管线若发生泄漏,会造成财产损失和海洋环境污染,及时发现泄漏并对泄漏情况进行分析和定位,可以减少损失,加强对管线的质量控制。文中研究了离岸油码头项目中海底管线的测漏系统,通过对现有的测漏技术进行比较和分析,提出了离岸油码头项目中海底管线测漏系统的实际应用方案,将负压波法和流量平衡法组合起来使用,能够使泄漏检测精度提高,误报警率降低,为该项目提供了一种可靠、高效的解决方案。

石化码头项目环境影响评价工程分析要点

石化码头项目环境影响评价的基础和关键为工程分析章节,直接影响后续环境影响预测与评价的内容和结论。按照水运工程、海洋工程、石化行业等相关标准和规范,结合石化码头项目施工期和运营期工程特点,通过某新建海港石化码头项目环评报告书工程分析的相关内容剖析,寻找其中可切入的同行业共同点,从而阐明石化码头项目环评报告书工程分析的关注点及评价要点。

Computation of Diffraction of Irregular Waves Behind Double Jetty

The coefficient of deffraction of regular waves behind the double jetty has been computed in this paper at first by using the singularity distribution method. The model tests conducted for diffraction of irregular waves with a unidirectional frequency spectrum have confirmed good agreement between the data measured in experiments and the results computed by the singularity distribution method plus the linear superposition method for the energy of component waves in the directional frequency spectra. Therefore, this technique for component waves in the directional spectra has been further used to compute diffraction of irregular waves of multidirection, including the employment of a directional distribution function of the cos2 type, as well as the Bretschneider-Misuyann frequency spectrum.

Effect of the Twin Jetties as A Regulating Structure at the Tao-er Estuary

The phase one project of the twin jetties at the Tao-er Estuary yields no effect on the flow, and there is a large area of deposition. A numerical model is employed to simulate the flow field, and the scouring and silting in the channel between the two jetties are analyzed. The results show that the effective tidal flux between the two jetties is reduced due to the notch located at the heel of the east jetty, and the effect of contraction-flush is not obvious. As for the regulation of this kind of estuary under the tide action, the capability of tidal flux should be fully used.

Computation of Diffraction of Irregular Waves Behind Single Jetty

This paper presents a calculation method for the diffraction of both regular waves and irregular waves of the single directional frequency spectrum behind a single jetty with a theoretical analysis, which has been confirmed through the model experiments, derives a method of computing the diffracted irregular waves behind the single jetty with the theoretical analysis on the basis of computation of the field data and gives the formulas and the figures of the computation of wave diffractions behind the vertical wall or mound single jetties.

The Behaviour of LNG Carrier Moored to a Jetty Exposed to Waves,Swell,Unsteady Wind and Current

Most terminals for tankers are piers and sea islands, while other types include single point moorings and multiple-buoy moorings. The LNG and LPG carrier moored to the jetty is a very common terminal for transfer of gas in open seas. It is important to estimate the motions and line tensions of the LNG carrier when it moors to a jetty in metocean environment. Normally, the motions of the LNG carrier would be restricted by the loading arm, which is connected to LNG carrier's manifold. An example of 125,000 m(3) LNG carrier moored to a jetty exposed to a set of environment conditions is given. A mathematical model which is based on the equations of motion in the time domain is used to the analysis of LNG moored to an offshore jetty exposed to waves, swell, wind and current. By means of a time domain computer program TERMSIM computations are carried out to determine and optimize the lay-out and / or orientation of the jetty and mooring gear in terms of forces in mooring lines and fenders and the envelope of motions of the loading arms. The purpose of this study is to determine the sensitivity of the mooring system and carrier motions to the combinations of wind waves with and without swell, steady wind and wind spectra. The results can be consulted by the designer in the design of jetties.

长周期波浅覆盖层无掩护海域离岸码头施工关键技术

依托巴基斯坦中电胡布燃煤电厂煤码头工程,针对长周期波浅覆盖层无掩护海域离岸码头施工的特点和难点开展研究,从“长周期波浅覆盖层无掩护条件下离岸高桩码头总体施工方案”、“长周期波浅覆盖层条件下钢栈桥施工方法”、“步履式液压顶推平台法钻孔灌注桩施工方法”、“长周期波及经历季风期外海孤岛防波堤施工技术”共4个方面,运用理论分析、现场实施效果、综合理论研究、科学试验多项手段,解决长周期波浅覆盖层无掩护海域高桩码头施工的技术难题,形成了成套的建设技术,为类似条件外海码头施工积累了宝贵的经验。

深中通道泄洪区非通航孔桥110 m跨钢箱梁转运落梁关键技术

深中通道伶仃洋大桥东、西泄洪区非通航孔桥为110 m跨连续钢箱梁桥,包括6联6×110 m、2联5×110 m,每联钢箱梁由133.1 m长首孔、110 m长中孔和86.1 m长末孔组成,主梁为分幅等截面船形钢箱梁(单箱三室结构,梁顶宽20 m、高4 m),共80片钢箱梁采用中山梁场转运,再由3600 t“天一号”运架一体船架设。钢箱梁在梁厂制造后,通过滚装上船,运输至中山梁场出海码头后,采用“浮托法”转运落梁。钢箱梁在码头通过模块车横向滚装上运输船,运输船上设置2根托梁,钢梁直接落在托梁上;运输船载着托梁和钢梁沿横门东航道行航行至中山梁场出海码头,运输船垂直进入码头中间,当托梁位置到达设计位置后,收紧锚绳,通过调整压载水舱和潮涨潮落,将钢箱梁和托梁落在码头上,完成钢箱梁转运落梁工作。采用浮托法转运落梁转运效率可达1片/d。

浮式天然气发电船码头系泊数值分析

针对发电船在近岸码头设计环境条件,采用挪威船级社(DNV)Sesam软件SIMA模块,对发电船系泊系统进行数值仿真分析,预测系泊缆、靠垫在各种工况下的系泊载荷,并与船级社规范要求进行对比分析,确保发电船系泊系统设计合理性。

基于服务器推送技术和XMPP的WebIM系统实现

为解决现有WebIM系统中大量用到AJAX周期请求而产生的系统消息延迟,以及客户端和服务器端通信量大的问题,提出了以服务器推送技术作为基础的WebIM系统,并选择XMPP作为服务器和客户端的通信协议。在比较AJAX和Comet技术原理的基础上,给出了Comet技术实现HTTP长连接的策略。通过一个原型WebIM系统,验证了Comet技术在WebIM系统中使用的确可以有效地解决大量AJAX周期请求的问题。

敏感因素劣化对导堤边坡稳定性影响的数值模拟

以吴淞导堤工程为案例,基于超声波现场检测及室内强度试验、探地雷达现场检测试验、潜水员水下探摸及测量结果,分别评价导堤在长期运营过程中护面混凝土结构、内部堆石结构、导堤两侧坡度变化以及两侧冲淤演变等敏感因素的劣化程度,并采用有限元数值模拟方法研究导堤护面混凝土结构等4种敏感因素劣化对导堤边坡变形及稳定性的影响。结果表明:导堤护面混凝土及内部堆石结构弹性模量与导堤水平位移最大值均呈负指数关系;导堤安全系数随着坡度的增大而呈现出近似线性减小;导堤位移的最大值随着导堤左侧淤积和右侧冲淤高程的增加呈线性增大,在实际加固维护方案设计中应该引起重视。

超声波法在检测导堤表面混凝土结构中的应用

基于超声波无损检测理论,建立了超声波检测混凝土结构强度的预测方法.以吴淞导堤表面混凝土质量检测为案例,比较分析了4 200个超声波法预测的和400个现场钻孔取芯实测的混凝土强度值.结果表明,混凝土强度实测值和预测值均近似服从正态分布,概率峰值区间分别位于12~16MPa和9~15MPa,分布密度分别为28%和23.26%,强度分布区域均为3~25MPa,且均小于设计值,预测结果和实测值吻合度较高.

软基上的空心方块斜坡堤

根据实际工程需要,提出了一种适宜建造在软土地基上的新的空心方块斜坡堤型式。这种新型结构是利用各空心方块之间以及空心方块本身的空隙,降低堤身单位体积的重量以及堤身断面总重量,从而满足软土地基承载力和整体稳定的要求。结合长江口深水航道治理工程的北导堤堤头部位2.6km长的软基段,对空心方块斜坡堤的设计和试验研究情况作概要介绍。