三峡水电站运行条件的特点与水轮机优选问题

三峡水电站水头范围大，最高水头与额定水头之比高，长期偏离最优工况运行，并且汛期水中含有一定数量泥沙．虽然三峡机组的容量尺寸与国外大古力、依泰普相当，单从机械制造角度看不存在很大困难，但要很好地满足运行条件，技术要求高，难度亦大．因此，通过对三峡水轮机性能进行初步分析，发现水轮机能量犄性将偏离最优工况，高侧水头时的空化与稳定性与磨蚀等问题将比较突出．为改善机组特性，对水头等参数的合理选择提出了一些看法．     

改善三峡电站水轮机稳定性的技术措施

三峡电站水轮机额定出力710MW，与世界上已投运的最大容量和尺寸的混流式水轮机相当。由于三峡电站水头变化范围起出了混流式水轮机常规的适应范围，故三峡水轮机的稳定性引起了国内外同行们的普遍关注。本文结合三峡特定的运行条件，提出了改善三峡水轮机稳定性的综合治理措施，并对各种技术措施进行了分析。     

水府庙水电站水轮机选型方案

水府庙水电站机组原HL365-LH-230水轮机为低水头混流式，在水力设计与性能方面存在缺陷。水电站在增效扩容改造工作中，根据现有水力条件，确定了水轮相纽改造的基本技术要求，确定了水轮机技术改造方案。实际运行效果显示，技改后椒轮机出力及运行稳定性得到了显著提高。     

水府庙水电站水轮机选型方案

水府庙水电站机组原HL365-LH-230水轮机为低水头混流式,在水力设计与性能方面存在缺陷。水电站在增效扩容改造工作中,根据现有水力条件,确定了水轮机组改造的基本技术要求,确定了水轮机技术改造方案。实际运行效果显示,技改后水轮机出力及运行稳定性得到了显著提高。     

长江三峡水轮发电机组参数选择的几个问题及建议

长江三峡水电站是世界上在建的最大水电站。水轮机水头变幅大；汛期低水头运行；枯期高水头运行时间长；对水轮机性能要求高，水轮发电机组参数选择难度大。根据三峡电站的特点建议：（１）、尽可能选择较大直径的水轮机，增大低水头过流能力，汛期多发电能；（２）、发电机应设一个８３０ＭＶＡ以上的最大容量，以扩大水轮机在高水头时的运行范围，提高稳定性；（３）、初期投入的６台机组使用初期转轮，库水位提高后更换永久转轮，     

三峡水电站ALSTOM机组低水头运行稳定性分析

混流式水轮机的水力稳定性与机组水力工况密切相关。以三峡电站左岸6号机组稳定性试验为例，分析了ALSTOM机组的低水头运行稳定性。根据试验分析结果，可将机组运行工况划分为小负荷区、涡带振动区、大负荷运行区。小负荷区机组效率较低，机组不宜在此区间运行；大负荷区机组运行稳定性最佳，但机组应避开强涡带工况区和特殊频率振动区运行。     

大型混流式水轮机稳定性研究及对策

混流式机组由于结构简单,适用水头范围广,制造技术较为成熟的特点在大型水电站的开发中占据主导地位,但由于混流式水轮机是固定叶片式的水力机械,机组运行稳定性和转轮叶片的裂纹是威胁水轮机安全运行的两大问题,本文通过对影响混流式水轮机稳定性的因素进行分析研究,并提出了一些提高机组运行稳定性的对策。     

混流式水轮机的水力稳定性问题

混流式水轮机的水力稳定性与机组运行工况密切相关。当水轮机在远离设计工况(最高效率点)运行时，会产生脱流和涡带，引起振动，并可能产生疲劳破坏。近年来，随着单机容量和水轮机尺寸的增大，有些电站因水头变幅大、负荷调节范围宽、水轮机性能不完全适应电站运行条件、制造质量存在问题和补气不力，水轮机出现不同程度的水力振动，导致转轮叶片裂纹，尾水管壁撕裂，有的甚至引起厂房或相邻水工建筑物发生共振，危及电站安全运行。本文对混流式(特别是高比速混流式)水轮机的水力稳定性问题进行了初步分析和讨论。     

三峡工程水轮发电机组若干技术问题

长江三峡水电站是世界上在建的最大水电站。电站水头变幅大，汛期低水头运行，枯期高水头运行持续时间长。三峡要组的参数选择除应满足低水头时多发需要外，还应保证水轮机在高水头时稳定运行，为此对如何合理地确定水轮机设计水头和适当增大发电机容量以改善运行稳定性问题进行论述，并对机组结构型式和发电机冷却方式也作了分析研究。     

三峡电站水轮机的技术特点分析

单机容量７００兆瓦的三峡水轮机，是世界上最大容量的水轮机之一，但比已投入运行的７００兆瓦水轮机运行条件更为复杂，主要体现在水轮机运行水头变幅最大，达６１－１１３ｍ之间，超过世界上已投入运行的５０ＭＷ以上的水轮机水头变幅，其次轮机运行在高水头区（１０５－１１０ｍ）及低水头区（７５－８０ｍ）时间较长，且需适应初期和后期两种蓄水位运行条件，此外，由于长江汛期水量大，含沙量大，含沙量少，在调度运行中，水轮     

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。     

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。     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。     

Fish assemblage response to recent mitigation of a channelized warmwater stream

Various designs of low‐head dams are used to rehabilitate streams or forestall upstream channel incision after channelization. We report on the efficacy of using notched sills and grade control structures (GCS) to restore the fish assemblage in Luxapallila Creek, Mississippi. We tested the null hypotheses that habitat variables and species richness, evenness, and assemblage structure would not differ among: (1) a channelized segment with no modifications; (2) a channelized segment mitigated by the installation of sills and GCS; (3) a segment upstream of the installations and undergoing channel incision; and (4) an unaltered segment. Although habitat variables changed, neither species richness, evenness, nor fish assemblage structure differed between mitigated and channelized segments with both exhibiting less richness and different assemblage structures than the unaltered segment. Lack of differences in species richness between the incised and unaltered segments suggest that the GCS may have halted the negative effects of upstream channel incision before species were extirpated. Conspicuous habitat differences between the altered (channelized and mitigated) and unaltered segments were lack of backwaters and canopy coverage and finer substrates in the altered segments. Our results suggest a more comprehensive rehabilitation strategy is required in Luxapallila Creek. Published in 2003 by John Wiley & Sons, Ltd.     

NUMERICAL STUDY OF WAVE EFFECTS ON SURFACE WIND STRESS AND SURFACE MIXING LENGTH BY THREE-DIMENSIONAL CIRCULATION MODELING

1. INTRODUCTION Coastal and continental shelf regions are characterized by intensive interaction between wave and current. These regions are of great economic significance to mankind. Therefore, the modeling of wave and current as well as their mutual int…