鄂北调水工程长倒虹吸事故水力响应及应急调度

以鄂北水资源配置工程中的孟楼-七方倒虹吸(全长约72 km)为研究对象,建立事故工况的一维非恒定流数值计算模型,仿真分析事故工况下长倒虹吸的水力响应过程。结果表明:事故工况下闸门同步异速调度相较于异步同速调度更利于倒虹吸安全;同步异速调度规则下,延缓倒虹吸进口以及上游闸门开始关闭时间、延长进口以及上游闸门关闭时长,或快速关闭倒虹吸出口以及下游闸门,都会抑制倒虹吸内部压力水体释放过程,增大压力超限风险;针对鄂北水资源配置工程,建议倒虹吸进口及上游闸门至少不晚于出口及下游闸门开始关闭后的30 min开始动作,倒虹吸出口及下游闸门关闭时长不宜短于30 min,倒虹吸进口及上游闸门关闭时长不宜超过30 min,并最终提出一组可供参考的节制闸应急调度组合。主要结论对于鄂北水资源配置工程的应急调度具有一定参考价值,也对类似含有大型倒虹吸工程的运行调度有一定的借鉴意义。     

南水北调中线干渠闸门同步关闭水力响应特性

构建南水北调中线干渠局部一维非恒定渐变流模型，以“刁河闸—湍河闸”渠池为例，测试闸门调控方式和 渠道运行条件对闸前壅水峰值水位、达到峰值水位所用时间、水力振荡频率、水力振荡幅度等水力响应特性的影 响。研究表明：水力振荡上升过程快，下降过程慢，波幅随时间呈对数函数衰减；闸前壅水峰值水位随闸门关闭速 度、闸门关闭幅度、输水流量、运行水位、渠道糙率的减小而近似线性地减小；达到峰值水位所用时间对输水流量、 运行水位和糙率变化不敏感，随闸门关闭幅度和输水流量的增加而近似线性减小；水力振荡频率对闸门关闭所用 时间、闸门关闭幅度、输水流量和糙率变化不敏感；水力振荡幅度对运行水位、糙率变化不敏感，随输水流量的增 大而快速衰减。     

闸坝型水库新型泄洪调度方法研究

传统的泄洪调度试验,通常针对单个流量级进行闸门调度优化研究,而没有考虑闸门开启或关闭的连续性。在实际洪水调度过程中,可能存在闸门升降反复运行,管理较复杂。以汉江孤山航电枢纽泄洪调度试验研究成果为依托,在模型试验中,需要在不同的流量之间反复调整闸门的开启组合方式,确保小流量已经开启的闸孔,大流量要继续开启,不够再开别的闸孔,且出闸底缘水流尽量为自由出流,避免淹没闸门底缘,以减轻水流波动引起的闸门振动,另外冲坑深度等指标也需要满足要求,提出了流量由小到大或由大到小闸门单向性连续开启或关闭的新型调度方式。该方法具有闸门操作简单、运行安全的特点。     

南水北调中线输水渠道的漫溢现象分析

针对南水北调中线输水渠道缺少调节水库的现实情况,采用一维非恒定流数学模型,模拟了渠道中某一节制闸出流量以不同速率关闭而导致上游渠道中出现的水流漫溢现象。结果显示,水流漫溢现象最先发生在被关闭节制闸前。闸下出流量的变化速率越快,出现漫溢的时间也越短,闸门关闭期间的闸前水位上涨速度与闸下出流量的变化速率呈线性变化关系。实际条件下,为尽量避免出现漫溢事故,应尽量缓慢关闭闸门,延长渠道出现漫溢的时间,以留出更多的时间去启动退水闸或其他分流设施。     

关于“北京模式口水电站提高出力叶负荷时水锤观测报告”的讨论

水利学报1959年第1期发表了“北京模式口水电站提高出力弃负荷时水锤观测报告”一文。我读后有如下意见愿与作者商榷。一、关于水轮机导叶(即该文中“闸门”)关闭终止时间的确定方法。该文第四节中说:我们认为水锤现象消失的时候,闸门完全关闭。这种说法是不正确的。实际上,水锤现象决不可能在导叶关闭完了时立即消失,而是要延续—段时间,方才逐渐消失的。     

溢流坝工作闸门关闭卡阻应急处理及预防措施

以某电站工作闸门关闭时卡阻为例,通过对产生原因的分析,提出简单实用的应急措施,通过该方案的实施,闸门已能顺利关闭,并根据多年工作经验,就闸门卡阻的原因及预防措施作简要阐述.     

浅析锦屏一级进水口闸门动水落门试验

在应用现代科学方法对锦屏一级水电站水轮发电机组进水口闸门动水落门安全性分析的基础上,对水轮发电机组在210 m高水头及600 MW满负荷状态下,完成了进水口快速闸门动水关闭试验。该试验为国内首次同类型高水头大容量水轮发电机组进水口闸门动水关闭试验,以验证进水口快速闸门在水轮发电机组事故情况下能否快速落门保证机组安全停机。     

铸造闸门在苏丹麦洛维灌溉工程的应用

介绍苏丹麦洛维大坝工程灌溉渠滑动闸门的设计经验,属小孔口高水头滑动闸门设计,门槽尺寸较小,动水启闭.达到闸门关闭后止水效果好、启闭过程中不发生射流,安装方便的要求.     

老龄闸门的检测和寿命的预测

所有闸门都有一定的使用寿命。由于每个闸门所处的使用环境和操作条件各不同,所以其寿命也不同,要通过对形变、材质和锈蚀的检测来计算其剩余的使用年限,从而准确判断其更换时间或采用必要的补强措施。既避免了盲目更换造成的经济损失,也可避免因更换或修补不及时造成的水利事故。本文着重论述了老龄闸门的检测方法和检测手段,以及闸门寿命的计算方法。     

磁力快速启闭机

小型水电站大部分是河床式或引水式,属无调节发电,不光水头、流量变化频繁,而且多数是直供电源,负荷极不稳定,就是並入国家电网,由于本身装机容量较小,即不能稳定系统电压,也调节不了峰差。再加上自动化程度不高,通讯设备不完善,当线路出现事故或系统突然甩掉负荷时,若调速器失灵,或导水机构出现事故,水轮机导水叶不能立即关闭,这时机组则发生过速或飞逸。有时压力管道出现紧急事故时,也要求进水口闸门在动水情况下能立即关闭。     

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。     

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.     

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。     

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.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

Desiccation and recolonization of phytobenthos in a regulated desert river: Colorado River at Lees Ferry,Arizona, USA

We tested the recolonization of the phytobenthic community in the tailwaters of Glen Canyon Dam following long- and short-term experimentally induced desiccation. The response of Cladophora glomerata, Oscillatoria spp., miscellaneous phytobenthos species and periphyton was studied over 18 weeks using three treatments: (1) undisturbed control cobbles from the submerged zone; (2) cobbles desiccated and replaced into the submerged zone; and (3) cobbles desiccated and replaced into the varial zone. Periphyton density and compositional response resulting from these treatments were also examined. Desiccation treatments were significantly different in biomass from controls throughout the study. The biomass of desiccated and replaced river cobbles averaged <30% of the controls for C. glomerata and periphyton during the 18-week recolonization period. In contrast, the biomass of the control Oscillatoria and miscellaneous phytobenthos species averaged only 3 and 50% of that in the desiccation treatments, respectively. Cladophora, the dominant alga, comprised 77% of the phytobenthic biomass. A significant positive relationship between discharge, Cladophora and periphyton biomass was present in all treatments, while there was a negative relationship with discharge for Oscillatoria and miscellaneous phytobenthos species. There was a significant inverse correlation, as well as a pattern of separate biomass dominance, between C. glomerata and Oscillatoria. Cladophora was the dominant phytobenthos species on cobbles below the baseflow and Oscillatoria was dominant on cobbles in the varial zone. In general, the Cladophora biomass decreased under intermittent drying conditions, while Oscillatoria declined under permanently wet conditions. Diatom composition was not significantly different between treatments; however, their density was lower on desiccated cobbles. Diatom density on desiccated cobbles in the submerged and varial zones averaged 69 and 42% of that of the controls, respectively. Recovery and maintenance of benthic resources are hindered by fluctuating flow regimes driven by electricity and irrigation requirements. Repeated desiccation of the phytobenthos has major effects on the bottom-up interactions in the Colorado River ecosystem. © 1998 John Wiley & Sons, Ltd.