城市河流规划探讨

针对现在城市河流暴露出的问题，总结城市河流改造工作，分析城市河流规划的多目标性，初步探讨了城市河流规划设计。     

环境评价中的河流水质模型

本文阐述与讨论了同冶金企业有密切关系的河流水质模型。     

某河流底泥重金属污染地质累积指数评价

通过对双桥河流域进行环境调查,采集了底泥样品,分析了重金属含量,应用地质累积指数对河流底泥进行了评价。其结果表明:汞的地质累积指数为-1.01～2.39,76.92%采样点为Ⅱ级,属于中度污染;铅的地质累积指数为-0.07～2.19,3.85%采样点达到Ⅲ级,属中度污染到强污染,65.38%采样点达到Ⅱ级,属中度污染;镉的地质累积指数为-0.32～1.55,30.77%采样点达到Ⅱ级,属中度污染,50.00%采样点达到Ⅰ级,属无污染到中度污染;铬、砷基本没有污染;铜、锌地质累积指数平均值为0≤Igeo<1,达到Ⅰ级,属于无污染到中度污染;汞、铅的污染较为严重。     

环境评价中的河流水质模型(续)

本文阐述与讨论了同冶金企业有密切关系的河流水质模型。     

矿区生态系统健康及其评价指标和方法

在总结一般生态系统健康理论的基础上,引申出矿区生态系统健康的概念及内涵;从自然、人为和社会经济因素3个方面分析矿区生态系统健康的影响因子,并以此为基础阐述了矿区生态系统健康评价指标体系的指标选取原则,将评价体系分解为活力、组织结构、恢复力、生态系统服务功能与人类健康5个要素;结合一般生态系统健康评价方法,简述了适用于矿区的生态系统健康度计量法、模糊综合评价方法和突变级数法.目前矿区生态系统健康研究还处在发展阶段,还需要在理论、"3S"等技术方面进行更深入及定量化的研究.     

河流样品有机物监测前处理方法研究进展

综述了国内外监测河流水体和沉积物中有机物的前处理方法,介绍了液-液萃取、液-液微萃取、固相萃取、固相微萃取、微波消解和微波辅助萃取、超临界流体萃取、免疫萃取、气体萃取(顶空技术)及其特点,并对未来的前处理技术发展方向进行了展望.     

河流沉积物中微量重金属的ICP发射光谱测定法

本文叙述了用扫描型等离子发射光谱仪测定河流沉积物中微量重金属元素的方法。讨论了样品中元素的干扰和样品的处理方法，用此法测试了地质部参考标准样品．取得与标定值一致的结果。     

河流污染二维水质模型研究及RMA4模型概述

介绍二维水质模型常用的模拟手段、建模求解步骤的要点难点,并在此基础上对RMA4水质模型的特点进行详细归纳和分析,最后探讨河流水质模型的未来发展趋势,从而为建立二维河流水质模型进行水质模拟提供一定的思路和依据.     

疏勒河流域移民安置工程对生态环境的影响

疏勒河流域处于河西走廊西部,气候干旱,生态环境十分脆弱,而随着人口的大量迁入,水土资源的大规模开发利用,会引起与地表水-地下水循环转化相关的生态环境变化.主要从水资源、耕地、人口、林地、草地、荒漠化土地方面的变化及其原因进行分析,研究移民工程对流域生态环境的影响.结果表明:疏勒河流域的水土资源开发利用总体趋势不断完善,人口与耕地、林地、草地、荒漠化土地具有正相关性,所以在以后的开发利用过程中,要以生态环境保护为出发点,以水土资源为核心,定发展、定绿洲、定林草,促进疏勒河流域生态环境的可持续发展.     

隧道健康动态评价模型与应用

在隧道健康安全评价的指标体系及其等级标准的基础上,通过规范化处理样本资料库中的元素,消除了指标类型和量纲的影响后,提出用集对分析方法构造可变模糊集的相对差异度函数,合理的确定了各层相关隧道健康评价指标处于级别标准区间的相对隶属函数,采用乘积标度法确定相关指标权重后,得出了隧道健康模糊综合评价动态模型.确定健康级别指标特征值后,结合实例计算证明了文中所提方法的科学性与合理性,有利于推动可变模糊集理论在土木工程领域的进一步发展.     

临水河河流沉积物对铀的吸附行为研究

沉积物对铀的吸附行为是铀在河流中迁移转化的一个重要环节,揭示其吸附规律对河流水体污染防治有重要意义。为了研究临水河河流沉积物对铀的吸附机制,采用静态吸附试验,分析吸附时间、pH、铀初始浓度、离子种类、重金属对不同埋深（0~10、10~20、20~30、30~40 cm,分别以L1、L2、L3、L4表示)沉积物对铀的吸附影响,同时进行吸附动力学模型和等温吸附模型拟合。结果表明,不同埋深沉积物对铀吸附效果不同,吸附容量排列顺序为L1>L3>L2>L4,主要与沉积物中有机质含量和化学成分有关。动力学模型拟合表明,L1沉积物对铀的吸附为物理吸附和化学吸附,L2和L3主要为化学吸附,L4主要为物理吸附;L1与L3可以用Langmuir等温吸附模型描述其吸附过程,吸附为单分子吸附。L2与L4的吸附特性符合Freundlich等温吸附模型,为多分子层吸附,存在于非均质表面。在不同吸附介质中,Ca2+、Mg2+、CO32-对沉积物吸附铀都产生明显的抑制作用,且抑制效果Mg2+>CO32->Ca2+;Cd、Pb、Cu、Fe对吸附铀也有明显的抑制作用。     

Kentucky River High Bridge

Cantilever bridge construction can be said to have started with the work of Heinrich Gerber in Germany in 1867. While the principle had been used in many ancient bridges, it was not until Gerber’s work that metal bridges were built using the cantilever principle. The Kentucky High Bridge over the Kentucky River was the first modern cantilever bridge built in the United States. While James Eads had used the cantilever construction method at St. Louis, his bridge acted in service as a series of three arches. The High Bridge, designed by C. Shaler Smith, was one of the most daring and innovative bridges built in the country and carried its load between 1876 and 1912, when it was replaced by Gustave Lindenthal’s three span truss.     

河道整治存在问题与解决方法研究

总结了河道整治在理念、规划、技术、管理等方面存在的问题;提出健康河流的新理念,对河道结构、社会服务功能、抗干扰能力等进行了全面规划.     

永定河河滨带土壤机械组成特征及异质性分析

[目的]研究永定河河滨带土壤机械组成特征及异质性分析,为河滨带土壤改良及生态修复提供理论参考.[方法]采用室外定点采样与室内测定分析相结合的方法,研究了永定河河滨带不同地段上下层(0～10、10～20cm)土壤的机械组成.[结果]永定河河滨带土壤机械组成中主要以砾石含量为主,黏粒含量较少,均低于5%.在砾石类组分上,10～20cm含量大于0～10cm含量,沙粒、粉粒则表现出0～10cm含量大于10～20cm含量,黏粒含量上下层间变化不明显.上、中、下游砾石、沙粒、粉粒含量变化幅度较大,而黏粒变化不明显.[结论]应根据土壤状况合理施肥,改良中要注意土壤机械组成恢复的合理结构.     

Spur Failure in River Engineering

Spurs are river engineering elements used to protect river banks from erosion and to concentrate flow to the river axis. Today, spurs are also employed for promoting environmental conditions along a river bank. These elements are characterized by a large variety of geometrical parameters, of which none is definitely fixed. Based on a preliminary study that identified optimum spur arrangements in a straight river reach the present research project adds to the protection of spurs by riprap. The first two spurs are demonstrated to require a suitable riprap for promoting nearly uniform scour conditions along the entire spur reach. This research investigated the effects of a variety of parameters on spur flow, notably spur length, spur spacing, spur height plus the diameter and the number of riprap rows, along with the main hydraulic and granulometric parameters. Design equations were established based on a large experimental campaign to predict riprap failure in terms of the previous set of variables. The failure modes are described along with a novel failure mechanism. The paper ends with a set of limitations allowing for the application of these results in river engineering.     

Hydrodynamic Loading on River Bridges

During a flood, a bridge may be partially or entirely submerged by the flow and the subsequent loading of fluid plays a major role in assessing the vulnerability of the structure. We have performed laboratory experiments to quantify the hydrodynamic loading on a bridge deck with rectangular cross section. We measured the time-varying hydrodynamic forces acting on the obstacle for various submergences and Deck Froude numbers. The experimental results have been analyzed via dimensional analysis and relationships between time-averaged force coefficients (drag, lift, and moment coefficients), the Deck Froude number and geometrical parameters of the problem are discussed and compared against relevant literature. Due to the presence of a free surface, force coefficients can be either larger (by more than a factor of 2) or lower than the corresponding values of the unbounded domain. The experimental drag coefficients are then compared with the results obtained by the momentum equation.     

Local Scouring at Bed Sills in a Mountain River: Plima River, Italian Alps

The main characteristics of local scouring below 26 bed sills constituting a sequence of grade-control structures in a mountain river (Plima River, Italian Alps) have been surveyed. Bed sills were built with concrete strengthened boulders and other loose boulders were placed in the river bed to enhance habitat diversity for fish. The most likely formative water discharge is used to evaluate specific flow energy at each bed sill. Measured maximum scour depths are well predicted by an empirical equation developed through laboratory results, showing an average relative error of 0.15.