抽水蓄能电站拦污栅桥梁设计标准及参数拟定研究

抽水蓄能电站拦污栅桥梁是连接抽水蓄能电站场内交通与进/出水口拦污栅的桥梁结构物，我国至今尚无针对此类桥梁结构的设计标准，以往大多采用公路桥梁的设计经验以及设计标准进行设计。然而拦污栅桥梁与常规的桥梁相比有其特殊性，若按照常规桥梁进行设计，大多数设计参数取值并不适宜。为此，以辽宁清原抽水蓄能电站进/出水口拦污栅桥梁项目为工程背景，结合抽水蓄能电站拦污栅桥梁结构的功能需求以及结构特点，从桥梁宽度的确定、设计荷载的选取、上下部结构形式的选择、附属设施的选择等方面将拦污栅桥梁结构的设计参数取值与常规公路桥梁的设计参数取值进行对比分析，给出了拦污栅桥梁结构设计参数合理取值的建议。同时，对于拦污栅桥梁结构的计算理论及设计荷载特点进行了说明，可为拦污栅桥梁结构的设计提供参考。     

白山抽水蓄能电站拦污栅振动研究

通过白山抽水蓄能电站拦污栅栅条、栅叶及水工整体等大比尺的结构模拟试验研究,分析拦污栅产生破坏的原因,对设计方案提出可供参考的建议.     

拦污栅结构中单根栅条振动特性研究

目前设计中,对拦污栅的共振分析设计标准是对单根栅条而言的,采用的是Levin公式,但是由于其中没有考虑周围栅条的影响而存在一些问题.单根栅条频率的计算应该考虑整个栅叶的影响,为此通过把周围栅条的振动自由度凝聚到目标栅条上,推导出单根栅条在整体栅叶影响下频率求解的广义特征方程,并推得单根栅条的真实频率,从而说明了整扇栅叶振动影响单根构件的机理,在此基础上提出了一个Levin修正公式.     

深圳抽水蓄能电站上水库进/出水口拦污栅设计

抽水蓄能电站的水道布置较为复杂，理想的进水口布置形式常受到输水道条件、扩散段体型等诸多因素的影响和限制。深圳抽水蓄能电站上库进/出水口的拦污栅的布置方式为将栅槽一侧轨道做成斜面，对应的拦污栅支承滑块与之保持对应的斜率，确保拦污栅放置入栅槽后栅叶上的支承滑块与栅槽的轨道面之间没有间隙的半固定式布置方式。实践证明，该布置方式可以有效限制栏污栅在栅槽中的振动，并且可以确保拦污栅的检修条件。     

抽水蓄能电站进出口水流流态及拦污栅的试验研究

根据潘家口电站抽水蓄能机组进出口水力学和拦污栅稳定性试验资料并参考国外有关文献，发现抽水蓄能电站拦污栅稳定性与进出口水流流态关系密切，除了采取防涡梁、防涡栅、导流墙外，改变拦污栅条稠密度，也可改善进出口水流流态，这样不仅对拦污栅稳定性有利，而且能提高机组效率。因此在抽水蓄能电站设计时应进行进出口大比尺水力模型试验，优化拦污栅结构设计。     

三峡电站进水口拦污栅设计

三峡水电站进水口采取单孔坝式小进口方案。两道拦污栅布置于进水口段上游侧，一道为工作栅、另一道为检修栅，利用坝顶设置的门机吊运。所有栅体均呈一列直线式布置；为了适应水位变化，采用活动式栅体多节布置；栅后各机组引水口间可相互补水。通过优化设计，三峡电站拦污栅选用桁架式实腹横梁结构，栅条断面为圆头矩形断面。经计算，与常规拦污栅相比，可减少水头损失１ ．１ ｃｍ ，每年可多发电能１ ２００ 万ｋＷ·ｈ 。     

天荒坪抽水蓄能电站上、下库进／出水口拦污栅设计

抽水蓄能电站运行的特点是具有发电和抽水两种工况，不论上水库还是下水库的进／出水口拦污栅都处于双向过流状态，水力条件比较复杂，上水库拦污栅在抽水工况和下水库拦污栅在发电工况流态较差，易诱发拦污栅的受迫振动，因此，我们除进行结构静力设计外，还进行了结构动力分析。     

天荒坪抽水蓄能电站上,下库进／出水口拦污栅设计

抽水蓄能电站运行的特点是具有发电和抽水两种工况，不论上水库还是下水库的进／出水口拦污栅都处于双向过流状态，水力条件比较复杂，上水库拦污栅在抽水工况和下水库拦污栅在发电工况流态较态，易诱发拦污栅的受迫振动，因此，我们除进行结构静力设计外，还进行了结构动力分析。     

基于基频的拦污栅优化研究

针对蒲石河抽水蓄能电站,以拦污栅第一阶自振频率作为优化目标,以拦污栅结构的各截面尺寸为设计变量,结构的系统质量、过水面积等为约束条件,进行了优化分析。优化结果表明,各种方案能大幅提高了结构自振频率,特别是弱加劲方案,提高达78.43%,大大提高了拦污栅的抗振性能。     

抽水蓄能电站拦污栅栅叶体型优化研究

抽水蓄能电站拦污栅的运行条件比常规水电站要恶劣得多,拦污栅破坏的机率也更高,研究不同体型栅叶的振动响应规律对拦污栅体型设计和拦污栅的安全运行具有十分重要的意义。本文在Nguyen等人研究成果的基础上,实验研究了长宽比为8的不同形状前后缘栅叶的振动响应特性,研究表明栅叶前后缘形状是影响栅叶振动强弱的主要因素,大倒角栅叶(接近流线型栅叶)既有较好的振动响应特性,又有很好的局部阻力特性,因此在拦污栅体型设计中应优先采用。     

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。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

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。     

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.