闭孔泡沫板在门槽导轨混凝土浇筑中的应用

检修闸门槽导向轨二期混凝土浇筑的施工及外观质量的控制一直是水利工程施工中的重点和难点,针对闸门槽导向轨二期混凝土浇筑中混凝土浆外漏严重影响外观质量的问题,总结出一种防止混凝土浆外漏保证施工质量的施工方法,该方法利用聚乙烯闭孔泡沫板作为基础材料,不仅有效的防止浆液外漏现象,也保证了浇筑外观质量。     

浅论水电站厂房蜗壳二期混凝土施工技术

水电站厂房施工中,蜗壳二期混凝土具有体型尺寸大、结构复杂、钢筋密集、温控要求高、浇筑难度大等特点。文章叙述我国几座大型水电站厂房蜗壳二期混凝土施工技术,提出在水电站厂房蜗壳二期混凝土施工中,为保证混凝土的浇筑质量,需要重点关注的几项主要施工技术。     

潘口水电站厂房蜗壳二期混凝土施工技术

为了控制和减小潘口水电站厂房二期混凝土浇筑过程中蜗壳的变形,经研究,决定采用通仓浇筑方案。由于电站厂房二期混凝土具有体型尺寸大、结构复杂、钢筋密集、温控要求高,以及浇筑难度大等特点。为了保证混凝土浇筑质量,施工前对混凝土浇筑施工的重点和难点进行了分析,并提出了有针对性的施工方案。由于浇筑方案合理有效,实际施工过程中严格组织实施,使二期混凝土浇筑取得了施工质量高、施工进度快的效果。     

清河水库溢洪道闸墩牛腿混凝土施工技术

文章阐述了清河水库溢洪道闸墩牛腿采用二期混凝土的施工方法。鉴于水库除险加固不能影响防洪,针对牛腿处无法改变模体尺寸等施工难点,故对部分中墩混凝土浇筑采用滑模施工,进行二期混凝土浇筑,而对边墩混凝土采用定型钢模板浇筑等方法。应用该技术,既保证了牛腿的浇筑质量,又加快了闸墩的施工速度,是一项成功的新型施工技术。     

向家坝二期工程大坝施工过程仿真研究

向家坝水电站右岸二期大坝包括右岸非溢流坝段和泄洪坝段,共21个坝段,混凝土工程总量为3904852m3.混凝土工程量较大,施工技术复杂,施工质量要求高,大坝浇筑方案采用了多种施工机械组合施工.本论文针对右岸二期大坝工程施工特点,对拟定的两个浇筑方案进行模拟,获得了详细的施工参数和指标,为大坝施工工期论证和优化浇筑方案提供了科学的依据.     

保温保压浇筑蜗壳二期混凝土的施工技术

蜗壳二期混凝土被称为水电站厂房混凝土的“心脏”，是最关键和最难浇筑的部位。三峡左岸电站厂房采用对蜗壳充水保温保压模拟运转状态浇筑二期混凝土。该技术是一项新技术，目前在国内外尚属首例，施工质量对机组的安全运行及振动稳定具有至关重要的作用。施工中针对保温保压浇筑蜗壳二期混凝土的技术特点，采取了相应的施工措施，如实施严格的混凝土温控，严格的施工监测，科学的分层分块，选择最佳的混凝土浇筑设备，严格控制混凝土配合比。通过这些施工措施，在有关各方的共同努力下，保证了混凝土浇筑质量，达到了预期效果。     

蜗壳二期混凝土施工及质量控制

水利发电工程中，蜗壳作为水轮发电机组的重要组成部分，提高和保证蜗壳二期混凝土施工质量更是关系到水轮机组整体质量，也为后期发电运行提供有利的保证。以实际水利工程为案例，分析施工重难点，分层分块研究蜗壳二期混凝土施工工艺及质量控制。通过实例研究，优化二期混凝土浇筑工艺，提高了混凝土浇筑施工质量，对控制水轮机蜗壳二期混凝土施工质量质量有所提高。     

恩内普坝更新

本文阐述了德国恩内普坝修复工程是如何利用施工检修排水廊道取代上游坝面大型混凝土衬砌浇筑而大大减少造价的。     

管型座二期混凝土浇筑及质量控制

贵港航运枢纽工程电站装机容量为4X30MW，机组采用KVEARNER公司生产的灯泡贯流式发电机组，为河床式发电厂房．管型座是机组传力机构，为机组的重要部位，其管型座周边二期混凝土浇筑质量，直接关系机组的正常运行．同时，由于周边结构复杂、浇筑面积窄小、施工困难，且技术要求高和质量要求严格，因此，管型座周边二期混凝土浇筑及质量控制是关键．1施工技术要求根据设计要求，混凝土标号为Rzs250，分层浇筑．管型座周边二期混凝土的分层一般为Zm一层，共分10个浇筑层（见表1）．共计混凝土量为3715m‘，层间歇期不小于4d．水平薄层…     

溧阳抽水蓄能电站蜗壳保压混凝土施工技术

溧阳抽水蓄能电站发电厂房为地下厂房,作业空间受限,其中主机间二期混凝土施工是其关键核心。如何保证蜗壳保压混凝土浇筑密实并满足设计要求是施工中的重点、难点。阴角自密实混凝土施工技术研究与应用达到了预期效果,为后续施工积累了宝贵经验。阐述了该项施工技术的实施过程。     

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。     

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。