土坝病害缺陷的层次分析法

利用层次分析结构模型建立了土坝病害缺陷评估模型,详细划分了各层次的影响因素,并给出了层次结构模型图,采用划分等级的方法对土坝病害缺陷进行等级评定.     

层次模糊评估法在水库土坝坝体质量评定中的应用

根据层次分析理论,将抽象化的、难以定量测量的影响土坝安全的指标逐层分解为现代检测技术手段可以做出分析的各项指标,建立土坝安全病害缺陷指标评价的逐阶层次结构思路,提出一种不确定性数学的定性与定量相结合的模糊评估方法。该方法避免了在水库大坝安全评价中人为主观因素较大,分析评价不够确切,甚至出现误判的现象。     

土坝的地震易损性和震害快速评估

该文搜集了我国近年几次大地震时处于5～10度地震区内的180座水库土坝的震害资料,经分析后把影响震害的因素定为坝高、“水深比”,地基条件,地震烈度;震害等级取为“严重”、“轻重”、“轻微”、“完好”。分别给出适用于地震危害性评估、表示土坝地震易损性的震害概率矩阵和适用于以确定性方法快速评估震害等级的表达式。最后并以某土坝的震害评估为例。     

明渠工程病险分级修复必要性评价方法

我国已逐渐进入病害水工程维护与管理的时代, 对水工程病害实施分级评估、 分级修复符合健康维护、绿色管理的可持续发展理念,有助于提高工程运维管理水平。针对输水明渠渠道工程,考虑病害危害性、工程维护等级、修复技术可行性、修复成本、病害发生时间五方面的影响因素,首先采用专家判断和序关系分析法进行了各因素的权重分析,结果表明病害危害性的权重系数最大,修复技术可行性和工程维护等级权重次之,病害发生时间权重最低。然后结合因素的四等级划分,得出病害修复必要性指数,据此可对不同状态、不同病害情况下的明渠工程进行分级修复评估。     

水闸溢洪道老化病害评估的层次分析法

本文以水闸、溢洪道的可靠性为总目标，以安全性，运用性、耐久性为子目标，建立评估指标体系，根据实际工程的老化病害情况，对评估因素分等划级，最后在考虑各因素对评估目标权重影响的基础上进行综合评估，得出对总目标或子目标的评价集或评价等级。     

水闸老化评判中的群决策和变权赋权法

提出了一种基于群决策和变权赋权法的水闸老化模糊综合评判方法．在研究水闸老化病害类型及影响因素的基础上，给出水闸老化病害评估准则，并构造水闸老化病害评估指标体系，建立了水闸老化病害评估的层次结构及相应的评估模型；根据水闸老化病害评估的特点并针对以往评估方法中赋权存在的缺陷，将群决策赋权法和变权赋权法引入模糊综合评判方法，提高了决定水闸老化程度和影响因素权重的科学性和民主性，进而可以系统地判别水闸的老化级别．最后用工程实例验证了该方法的可行性．     

土坝渗漏非接触式红外热像探测方法试验研究

渗漏是土坝工程最为常见且危害性极大的典型病害。快速探测与定位渗漏隐患，对保障工程安全具有极为重要的意义。充分考虑土坝渗漏与温度的关联特性，开展了基于红外热像的土坝渗漏非接触式探测方法及其试验研究，在对其基本原理与影响因素予以剖析的基础上，通过设计和搭建试验平台，开展了多种工况下的土坝渗漏红外热像探测试验，充分验证该探测方法可行的同时，明晰了土坝渗漏出口的温度发展规律及红外图像特征，可为土坝渗漏的快速探测和识别提供一定的经验参考。     

自由水库大坝病险量化评价分析研究

以辽宁省凤城市自由水库为工程背景,针对水库土坝的裂缝、渗漏、滑坡、护坡破坏等问题进行了病险分析研究,建立了土坝老化病险程度评价指标,应用多因素分析法对土坝病险情况进行了量化评价分级,定量判断自由水库大坝病险等级为Ⅱ级,即认为大坝主体结构基本完好,部分附属结构老化损坏,大坝整体功能可以基本发挥.     

电法勘探在陆浑灌区渠道过沟填方坝上的应用

本文以陆浑灌区六座渠道过沟填方集库结合土坝工程的隐患探测为实例，介绍了电测法在坝体裂缝及漏水通道等探测和土坝病害处理中的应用．     

大洪河土坝变形分析

大洪河土坝自建成至今已运行40余年，积累了宝贵的原型观测资料，本文通过对其大量原观变位资料的统计分析及不同埋深测点测值的对比分析，探讨了大洪河土坝的变形规律，同时，根据建立的数模，进行了逐步统计模拟，深入分析了各因子对大坝变位的影响程度，从时空和定性定量两个方面论证了大洪河土坝变位的收敛性。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.