沿海地区桥梁灌注桩混凝土配合比设计

对沿海地区灌注桩的配合比设计进行研究,可以进一步提升施工项目的质量,减少海水侵蚀的病害。结合临港工业园区道路的施工实践,可以总结灌注桩与混凝土的不同配合比设计的可行性。     

长沙湾大桥立柱耐久性加固与综合防腐技术

长沙湾大桥是一座跨海湾大桥,受海洋腐蚀性气候的影响较大,许多立柱都出现了混凝土保护层整层剥落、钢筋严重锈蚀等病害。针对该桥的病害,采用了多种技术措施对其进行处理,包括干轧混凝土及环氧混凝土修补缺陷、涂刷迁移渗透型阻锈剂、外包高性能混凝土、粘贴高强玻璃纤维布、防腐油漆涂装等技术。文中主要介绍这些技术措施的工作原理、施工工艺等,为同类工程提供参考。     

长江上游综合交通枢纽构建思路

本文界定了长江上游综合交通枢纽的内涵,通过分析系统的构成要素、港站与集疏运体系结构,提出了以宏观功能布局引导与需求强度布设支撑的长江上游地区综合交通枢纽构建思路．分析阐述了重庆构建长江上游综合交通枢纽的基本原则和关键问题。     

长江口海水密度对船舶安全和效益影响的分析

我国沿海河口港较多，利用港区的海水密度变化，在保证船舶安全通过浅水区的前提下，争取最大载货量，提高经济效益，值得引起广大船长和驾驶人员重视。     

Physical processes in the ROFI regime

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.     

东部沿海铁路桥涵勘察设计中必须关注的问题

东部沿海铁路通道是我国铁路路网规划“八纵八横”的重要一纵 ,受自然条件影响大 ,工程环境恶劣 ,致使桥梁建设技术复杂难度大。笔者结合工作实践 ,指出所要关注的重点问题及处理思路。     

A Tool for Coastal Setbacks Demarcation over Rough,Impermeable Shores: The Test Case of Kavala Coastline (Northern Greece)

Although setback zones and lines are considered as a powerful coastal zone management tool ensuring public access, protecting the coastal ecosystem and minimizing natural hazards over developments, the lack of a solid and objective Mediterranean methodological framework for coastal setbacks demarcation appears profound. Especially for countries like Greece, this deficiency leads to long legal disputes encouraging illegal construction on the coastline. In this article a methodology on coastal setbacks demarcation over rocky, impermeable shores is proposed, followed, and implemented along a Greek shoreline, serving as a pilot case study. The methodology is consistent with the requirements of the integrated coastal zone management (ICZM) Protocol and the Greek legislation (L. 2971/2001), aiming to determine the “highest winter waterline,” accounting for the tidal and storm surge effects, the sea-level rise due to climate change impact, the extreme offshore wind and wave analysis, and the maximum potential wave run-up. Such a tool may bridge the gap between legislative provisions and actual ICZM Protocol implementation improving regional coastal management and planning.     

超浅埋大断面滨海软土隧道施工工法研究

拱北隧道为一座滨海软土隧道,开挖断面达340 m2,采用超前管幕预支护下的多台阶分部开挖方案。采用ANSYS软件对五台阶15分区方案和四台阶8分区方案的隧道结构受力规律及安全性进行了数值研究。研究结果表明:1)采用五台阶15分区方案和四台阶8分区方案都能够满足结构安全要求,但在临时支撑拆除过程中,2种方案的施工安全性差异较大;2)四台阶8分区方案在下半断面临时支撑拆除后、三次衬砌尚未施作时,下半断面边墙及仰拱处的初期支护和二次衬砌受力较大,施工安全性较低;3)各部开挖后应及时施作初期支护,并应尽快施作第2层衬砌结构,以减小拱顶下沉和地表沉降。     

沿海水路运输外贸动态冲击因素研究——基于状态空间模型的分析

我国海洋外贸运输在全球外贸运输中发挥重大作用,而港口是国际物流运输的重要环节.基于状态空间模型,考察了金融危机之前及之后,国际、国内主要宏观因素对我国沿海港口外贸货物吞吐量的影响轨迹.结果发现:自金融危机以来,世界经济状况对我国沿海港口外贸货物吞吐量的边际正面影响在逐渐提高,外商直接投资的边际正面影响明显减弱,人民币实际有效汇率指数波动的边际负面影响在减弱,国内经济状况的边际正面影响逐渐减弱,沿海交通建设固定资产投资的边际正面影响在增强.基于实证结果,得出我国经济由外需拉动向内需推动转型的间接证据并提出政策建议.     

海港总体设计关键技术及展望

梳理了我国水运工程近十多年来在海港总体设计方面取得的多项创新成果,重点对港址选择,港区平面形态分类,港口水域尺度,码头掩护程度划分标准,码头高程、水深、长度等主尺度确定等几个关键技术的核心内容和应用情况进行了简要论述,展现了我国海港总体设计领域最新的发展成就和对专业学科领域知识体系的引领作用。