五强溪水电站水库防洪效益分析

五强溪水库除承担水力发电任务外 ,还承担下游沅水尾闾地区的防洪任务。根据尾闾地区蓄洪垸洪灾损失调查 ,针对五强溪水库拟定的不同防洪高水位方案 ,采用五强溪水库拦截超额洪量替代堤垸蓄洪的计算方法 ,绘制各防洪高水位方案沅水尾闾地区的洪灾损失频率曲线 ,结合五强溪水库 1995年投产以来的实际防洪效益 ,进行综合分析 ,得出了五强溪水库各防洪高水位方案的多年平均防洪效益。     

沅水上游水电站投运后对发电效益影响分析

为分析沅水上游水电站投运后,对五强溪水电站发电效益的影响,首先根据流域实际来水还原计算五强溪的天然来水过程,利用还原计算的天然来水,按五强溪实际运行控制水位计算发电量,五强溪实际年均发电量比还原计算年均发电量增加3.297亿k W·h。通过梯级水库的调节、补偿作用,可显著增加五强溪及梯级水电站的发电效益。     

五强溪水库汛期水位动态控制运用研究

沅水的洪水特性分析与降低五强溪水库汛期限制水位的防洪作用及其对电站效益的影响分析表明，五强溪水库主汛期防洪限制水位由设计的98m降低到94∽96m运行，对电站的发电运行有较大的影响，而所能增加的防洪作用有限计算表明，通过预报预泄在洪水预见期内可将五强溪水库起调水位降低3～5m，可起到同样的防洪作用。为此提出，存实际运用中应结合气象水文条件并考虑预报预泄措施，对该水库实行分时段汛期水位动态控制运用。这样可更好地协调防洪与发电的矛盾     

五强溪水电站二期截流工程的施工

五强溪水电站位于湖南省沅陵县境内的沅水上,装机容量120万kW,是湖南省发电量最大的水电站,也是我国“八五”计划的重点工程。该工程计划分两期施工,根据1994年实现第一台机组发电的目标,五强溪二期围堰系统工程必须在1992年汛前全面完成。     

五强溪水库建库前后水质变化分析

根据湖南五强溪水库建库前后多年水质监测资料,采用对比分析的方法,结合污染源的分布与变化,分析了五强溪水库水质时空变化及其原因,结果表明：五强溪水库建成运行后,水库具有较强的自净作用,建库前后水质变化较小,总体保持良好状况。近年在其库周和上游污染物排放增加、总磷、总氮超标的情况下,水库未发生总体富营养化现象。     

水库防洪调度风险评估

在水库防洪实时调度工作中,一般采用常规调度,有时也采用预报调度.以湖南省五强溪水库为例,运用模糊综合评判及多因素评判指标的数学方法,对水库防洪调度风险进行了定量分析,并研究了五强溪水库防洪调度中风险主体的数量特征关系和变化,以确定其风险率(风险度),从而提出水库防洪实时调度风险度的评判方法.     

五强溪水库汛期洪水间隙期超蓄能力探讨

文章从气象预报、水文预报有效预见期分析的基础上,对五强溪水库入库洪水基本规律、发电消落能力、雨季结束时间水库蓄满率等进行了分析,提出了五强溪水库汛期洪水间隙期内超过汛限水位的蓄水方案。     

五强溪运行对沅水尾闾排涝负效益分析

文章采取多种途径，计算分析了五强溪水库运行后，对下游沅水尾闾排涝所带来的不利影响。负效益定量的准确性尚有待进一步研究。     

金沙江下游梯级及三峡水库消落次序研究

随着长江上游大型水库相继建成投运,各水库间汛前集中消落矛盾日益突出。为探究梯级水库合理消落方式,以金沙江下游乌东德、白鹤滩、溪洛渡、向家坝梯级(以下简称“金下梯级”)和三峡水库为研究对象,拟定3种消落方式(提前消落、均匀消落、推迟消落),对比分析不同消落方案下梯级水库消落期综合效益,提出梯级水库最佳消落次序。结果表明：消落期间,多年平均来水条件下,在防洪安全得到保证时,采用乌东德-白鹤滩梯级均匀消落、溪洛渡-向家坝梯级推迟消落、三峡水库推迟消落方案,五库总发电量最大,为1 039.22亿kW·h;梯级水库均推迟消落时,出库流量低于最低下泄标准的风险最低;乌东德-白鹤滩梯级均匀消落、溪洛渡-向家坝梯级提前消落、三峡水库提前消落时梯级水库补水利用率最高,对应弃水量为22.45亿m~3。综合发电、航运、生态、补水等多方面效益,推荐最优消落方案为金下梯级均匀消落、三峡水库推迟消落;在来水极端偏丰或偏枯时,应结合预报及时调整为均匀消落方式。研究成果可为发挥长江上游水库发电、航运、生态、补水等综合效益提供参考。     

沅水流域"04.7"洪水及水库实际调度分析

文章对沅水“04.7”暴雨及洪水的发展过程、特点进行了详尽分析，同时对五强溪水库在此次洪水调度中所发挥的作用以及所取得的防洪效益进行了阐述。     

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.