流溪河拱坝混凝土开裂检查分析

本文介绍了流溪河水电站拱坝混凝土开裂情况的检查和分析结果，进一步了解了流溪河拱坝混凝土的现状，以便更好地管理好大坝，确保本厂大坝安全运行。     

流溪河拱坝混凝土开裂检查分析

本文介绍了流溪河水电站拱坝混凝土开裂情况的检查和分析结果，进一步了解了流溪河拱坝混凝土的现状，以便更好地管理好大坝，确保本厂大坝安全运行。     

浪详水电站运行期水库大坝安全监测分析

浪详水电站为C15混凝土砌毛石拱坝,为监测大坝的安全运行,在大坝布置了垂直位移、水平位移、挠度、缝隙及扬压力等监测设施,根据水库蓄水后4 a的观测资料,对大坝的垂直位移、水平位移、挠度、坝肩缝隙、扬压力观测资料进行了分析,评价了大坝的安全性和资料的可靠性。分析成果表明,大坝是安全的。     

信息窗

国家电力监管委员会颁发《水电站大坝安全注册办法》和《水电站大坝安全定期检查办法》本刊讯为加强对电力系统水电站大坝运行安全的监督和管理,使水电站大坝的安全注册及安全定期检查工作更加规范化、制度化和标准化,保证水电站大坝安全运行,根据《水电站大坝运行安全管理规定     

国家电力监管委员会颁发《水电站大坝安全注册办法》和《水电站大坝安全定期检查办法》

为加强对电力系统水电站大坝运行安全的监督和管理，使水电站大坝的安全注册及安全定期检查工作更加规范化、制度化和标准化，保证水电站大坝安全运行，根据《水电站大坝运行安全管理规定》，国家电力监管委员会制定印发了《水电站大坝安全注册办法》和《水电站大坝安全定期检查办法》，     

信息动态

·辽宁参窝重力坝和安徽梅山连拱坝的大坝安全自动监测系统已分别于1989年12月及1990年5月投入运行。·碾压混凝土拱坝科研协调会1990年3月10日至14日在贵阳召开。·四川电力局召开狮子滩大坝定期检查工作会议。·西北电管局召开石泉水电站大坝安全检查第二次工作会议。1990年3月5日至3月1日开会。出席会议的有石泉电站大坝安全鉴定专家组全体成员以及设计、施工、运行、科研等方面的有关专家和     

水电站大坝安全定期检查和评价

1前言大坝安全定期检查是政府行使大坝安全监察的一项重要制度,也是确保大坝安全运行的重要举措。大坝安全监察中心(以下简称“大坝中心”)从1987年开始,有计划、有步骤地对我国电力系统的水电站大坝安全开展首轮定期检查工作,到1998年为止共完成了96座水电站大坝的定期检查工作;通过首轮定期检查,基本上掌握了80年代前投入运行的水电站大坝的安全状况,查明了影响水电站大坝安全的一些缺陷和隐患,解决了一些多年来悬而未决的重大问题,查出了一些病坝、险坝,推动了大坝补强加固、监测系统更新改造等工作;同时,通过定期检查,增强了水电站运行…     

特高拱坝在线安全评判研究与应用

首先通过分析拱坝破坏案例,研究目标特高拱坝结构特点,对特高拱坝在线安全评判进行了研究,得到了安全评判的模型。其次,对信息融合方法进行梳理比较,认为采用规则推理法来评判大坝安全的适用性最强。最后,基于《水电站大坝运行安全评价导则》建立规则推理体系,开发了在线安全评判平台。研究成果在锦屏一级特高拱坝的应用案例表明,在线安全评判平台能实时、准确评判大坝安全状况。     

对《水电站大坝运行安全监督管理规定》有关大坝安全定期检查内容的解读

从定期检查的作用、定期检查周期、定期检查组织形式、特种检查程序、大坝评定标准、病险坝处理、不进行定期检查的后果、监管机构的相应职责8个方面对《水电站大坝运行安全监督管理规定》有关大坝安全定期检查内容进行解读。     

水电站大坝安全等级评定中边坡因素的影响剖析

基于我国水电站大坝安全定期检查的长期实践经验,分析了运行水电站边坡失稳对大坝运行安全的主要影响后果,归纳了边坡稳定状况评价的主要工作和原则,提出了边坡安全级别确定的原则。     

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.     

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.     

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。