构皮滩水电站泄洪消能设计

构皮滩水电站坝址河谷狭窄，洪水峰高量大，枢纽最大泄洪功率为4．2万MW，位居国内外拱坝前列，泄洪与消能防冲设计是工程的关键技术问题之一。通过方案比选，推荐采用坝身孔口泄洪，坝下设置水垫塘消能，岸边设1条泄洪洞，采用预挖冲坑挑流消能的布置方案。施工阶段，根据工程进度及现场施工情况对泄洪洞及二道坝的布置进行了调整。并对透水护坦长度及结构形式进行了优化。     

水布垭水利枢纽岸边溢洪道设计

水布垭水利枢纽具有水头高、流量大、地质条件复杂、建筑物布置集中等特点.因消能区地层抗冲能力差,故泄洪消能设计难度较大.经多方案比选,泄洪消能建筑物采用岸边溢洪道全表孔布置方案,溢洪道采用阶梯式窄缝鼻坎挑流消能,下游防冲建筑物采用护岸不护底的防淘墙方案.阐述了泄洪消能特点及设计原则,对溢洪道布置、泄洪方案、消能方案、溢洪道结构设计进行了介绍.     

雷公井水电站泄洪建筑物布置方案优选

雷公井水电站泄洪建筑物的布置,根据工程区的地形、地质条件,水文特性及枢纽布置方案的比较论证,泄洪建筑物采用了坝身高,中坎自由挑流联合泄洪方案。经水工模型试验论证,泄洪能力和消能防冲满足泄洪安全要求。取得较好满意的效果。     

构皮滩水电站泄洪消能设计

构皮滩水电站坝址河谷狭窄、洪水峰高量大, 枢纽最大泄洪功率为42 000MW, 位居国内外高拱坝工程前列, 泄洪与消能防冲设计是本工程的关键技术问题之一。通过方案比选和水工模型试验研究, 推荐采用坝身孔口泄洪、坝下设置水垫塘消能、岸边设1条泄洪洞、采用预挖冲坑挑流消能的布置方案。     

宝珠寺水电站枢纽布置及泄洪消能方案研究进展(下)

三、第二阶段试验研究(1985—1990) (一)中间坝后式全挑流消能(85方案) 1、方案来由此方案系由(78方案)改进而来。1983年“宝珠寺水电站初步设计中几个有关问题的审查会议”在对厂前挑流和中间坝后式布置方案进行了复议之后认为二者都是可行方案,但考虑到施工条件,仍同意采用中间坝后式布置。会议强调要抓紧继续进行泄洪消能试验工作,适当调整孔口布置,以改善泄洪消能效果。于是,就产生了(85方案)。     

拉西瓦电站泄洪布置方案的模糊综合评判

本文是“峡谷区高混凝土拱坝枢纽泄洪消能布置方案模糊综合评判的结构模式”一文的续篇,以该文中建立的模糊综合评判结构模式为基础,利用模糊综合评判的基本理论,采用两个评判模型及通过专家访问确定的6种权重分配,对黄河上游拟建工程拉西瓦水电站坝后窑洞式厂房岸坡泄洪枢纽总布置的5个泄洪消能布置方案进行了模糊综合评判,得到了5个方案的最终排序.本文为枢纽布置及泄洪消能布置方案的合理选择,提供了一套新的工作程序和方法.     

三里坪水利水电枢纽工程泄洪消能设计

三里坪水利水电枢纽工程泄洪消能设计采用坝身表、中孔集中泄洪和坝下天然水垫塘消能方案。泄洪布置实现了“最大限度地使落水点在横向、纵向上拉开”的设计原则,坝下天然水垫塘消能指标适中,两岸简单防护,消能设施布置简洁。水工模型试验显示,三里坪大坝坝身泄洪建筑物总体布局合理,表、中孔体型布置满足要求,坝下天然水垫塘防护方案可行。     

苗尾水电站溢洪道结构与基础处理优化设计

结合水工模型试验及技施阶段现场施工情况,对苗尾水电站岸边溢洪道布置、水力设计、结构设计及基础处理设计的优化情况进行介绍。苗尾水电站地处云南澜沧江中游峡谷,具有下泄流量大、水头高等特点。因下游消能区基岩抗冲能力差,故泄洪消能设计经多方案比选,泄洪消能建筑物采用岸边开敞式溢洪道全表孔布置方案,溢洪道采用差动式挑流鼻坎消能,下游防冲建筑物采用护岸不护底的方案。     

高拱坝大流量全坝身孔口泄洪消能布置设计方案研究

本文以叶巴滩工程为例,结合同类工程经验,对泄洪消能布置格局、坝身孔口布置、空中消能方式、水垫塘衬护方式及二道坝设置必要性等方面进行研究和综合比选,推荐采用"全坝身孔口泄洪(坝身布置5个表孔+4个深孔)、坝身分层出流、水舌空中无碰撞、坝后设水垫塘及二道坝"方案,满足工程安全性及经济性要求.     

大朝山水电站泄洪消能及排沙建筑物设计

大朝山水电站采用表孔和泄洪排沙底孔联合泄洪的泄洪消能方案。中小流量时，以泄洪排沙底孔、冲沙孔和机组泄流为主；中大流量时，则以表孔、泄洪排沙底孔、冲沙孔和机组联合泄流。表孔采用宽尾墩，台阶式坝面和戽式消力池消能工，泄洪排沙底孔和冲沙孔采用窄缝异型挑流消能。新型台阶式坝面对加快碾压混凝土坝的施工进度、节省工程量和提高工程效益具有积极的意义。     

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.