船闸输水系统的水工模型缩尺影响

本文叙述了通航船闸输水系统的水工模型缩尺影响。通常输水系统总阻力系数主要由廊道闸门段损失,廊道局部损失(其主要部份为出水孔段损失)以及廊道沿程摩阻损失等三部份组成。模型试验及相应的原型观测表明,前两种损失在廊道水流雷诺数 Re≥5×10~4以后,即和雷诺数无关,亦即与模型缩尺无关,而模型与原型之间沿程摩阻损失系数的差异是导致原模流量系数不相同的主要原因,这也就是为甚么在输水阀门开度η≥0.8以后原型流量系数大于模型流量系数的原因。为了更准确地确定原型流量系数及其他输水水力特征值,需要进行相应的糙率校正计算,特别是当模型比尺较小时。     

船闸输水廊道复合管单支孔阻力系数试验

通过系列模型试验，对灌水状态和泄水状态复合管单支孔阻力系数进行了系统的研究，得到了单支孔阻力系数与支孔几何形状参数、流速比和廊道雷诺数之间的变化规律，建立了单支孔阻力系数的一般计算公式。     

船闸输水廊道复合管单支孔阻力系数试验

通过系列模型试验，对灌水状态和泄水状态复合管单支孔阻力系烤进行了系统的研究，得到了单支孔阻力系数与支孔几何形状参数，流速比和廊道雷诺数之间的变化规律，建立了单支孔阻力系数的一般计算公式。     

化学灌浆在坝基灌浆廊道裂缝处理中的应用

狮子坪水电站坝基灌浆廊道在＂5.12＂大地震后出现贯穿性裂缝,渗水较严重。针对裂缝特点及难点采用化学灌浆进行处理,最终达到廊道不再渗水的效果。阐述了针对堆石坝坝基灌浆廊道裂缝采用的化学灌浆材料、灌浆施工工艺及灌浆后的质量检查措施。     

三峡永久船闸输水廊道水动力学特性研究

该文对三峡永久船闸末级闸首阀门段输水廊道进行了数值模拟,对阀门段输水廊道的内部水流流动特征进行了分析,并研究了阀门后廊道顶部的压力特性,分析比较了以不同速率开启阀门及不同开度下紧急关闭对阀门段输水廊道内部流场的影响。将二维结果与三维结果及实验结果进行对比,变化趋势基本一致,验证了边界条件提法的合理性及数值方法的可行性。该研究对永久船闸阀门开启速率及紧急关闭时阀门开度选择具有一定的指导意义。     

三峡厂坝预制廊道施工设计及施工技术

三峡大坝内设置了基础灌浆廊道、不同高程的排水廊道、交通廊道及各类专用廊道.因种种原因,预制廊道在水工建筑物中运用不够普及.现浇混凝土坝内廊道的模板设置、钢筋绑扎、混凝土浇筑、模板拆除等只能在狭窄的空间内进行,且都靠人力施工.为此,将廊道周边小断面作为混凝土制品事先进行制作,然后再运进现场进行拼装,可使施工省力并缩短工期.     

葛洲坝1号船闸输水系统水力学模型试验研究

葛洲坝1号船闸输水系统共进行了4个方案的模型试验研究。最后确定,4区段8根纵支廊道顶孔出水盖板消能的方案作为设计方案。本文简要介绍输水系统方案的选择情况。对试验确定的设计方案,重点叙述输水系统进水口及泄水口的布置;阀门段廊道的高程及体型;闸室中间廊道(第1分流口)及支廊道进水口(第2分流口)的型式;支廊道出水孔的布置和消能盖板的型式。文中亦给出了灌、泄水的水力特性、阀门后最低压力变化及闸室停泊条件等资料。     

水电站坝前廊道回填施工技术与应用

为了满足前期工程施工需要,在坝前布置廊道,廊道需要在坝前进水前完成封堵。由于坝前挡水对回填混凝土封堵的质量要求非常高,若回填质量不好,进水后将出现渗水现象,后期难于处理,因此回填完成后要进行回填及接缝灌浆。     

化学灌浆在混凝土裂缝渗漏处理中的应用

云南苗尾水电站廊道混凝土浇筑及灌浆后,经现场查看发现大坝廊道内混凝土表面有渗水裂缝。分析裂缝产生的原因,针对不同裂缝采取化学灌浆、表面封闭等措施进行处理。处理结果表明,化学灌浆在对原混凝土破坏较小的基础上较好地解决了渗漏及结构补强问题。通过对苗尾水电站大坝廊道混凝土裂缝处理措施的总结,介绍了裂缝处理的工艺和方法,可为类似工程提供经验。     

碾压混凝土坝廊道层快速施工技术

结合DG水电站碾压混凝土坝的实际条件,采取钢筋混凝土预制廊道及爬坡段廊道钢支撑悬空安装技术,并对廊道层的仓面分区、浇筑顺序、入仓方式等进行全面优化,廊道局部转角部位采用现场浇筑等一系列有效的工程措施与施工工艺,既加快了碾压混凝土坝在廊道层的施工进度,也保证了工程质量。     

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。