阿克苏市引水口防洪护岸工程设计

本文从阿克苏市引水口防洪护岸工程实际出发,分析了项目所在台兰河的河势演变,结合边岸相对稳定起始位置及引水功能,进行了引水口上下游河堤护岸防洪工程设计,包括冲刷深度计算、堤基高程确定、井柱桩透水丁坝设计、引水口渠底及边坡防冲护底护坡设计以及反滤层设计与方案比选等,除此之外,还应该考虑护岸对水流的主动消能。     

金沟河引水枢纽除险加固工程消能防冲方案比选

金沟河引水枢纽在长期使用中出现了淤积、老化等不良现象,通过类似工程消能防冲方案总结,结合金沟河工程特点,选取消力池、裙板消能两个方案进行比选,从经济、效能效果等多个方面综合考虑选取消力池方案作为防冲方案可以有效保护下游河道。     

平原区水闸闸下消能防冲与闸门控制运行

针对平原区水闸闸下消能防冲与闸门控制运行的特点,基于水力学理论分析,导出了消力池最大深度的计算公式。以沙颍河郑埠口水利枢纽工程为例,确定消力池的设计方案。根据消能防冲应满足的水流条件,由系列模型试验资料绘制了闸门控制运行曲线图,继而依据该图制定了满足消能防冲要求的闸门控制运行方式。应用结果表明,采用该消力池方案设计并按此闸门控制方式运行,能很好地满足消能防冲要求。     

岗曲河二级水电站消能防冲试验研究

通过模型试验,对岗曲河二级水电站泄洪消能方式、消能工体形和下游护岸措施进行了研究。在此基础上,提出了一种新的联合消能防冲体系(推荐方案),即闸后跌坎+齿坎消力池+钢筋笼防护。试验研究表明,这种新的消能防冲体系泄洪流态良好,消能效果理想,下游护岸安全稳定,成功地解决了该工程的消能防冲问题。     

中小型渠首工程消能工水流特性模型试验研究

中小型引水渠首工程由闸室、护坦、防冲槽等主体结构组成。通过模型试验,研究分析相同地质条件及同等边界条件下消能工的工作规律,掌握消能防冲槽在无抛石或有抛石工况下消能工的水流特性,为消能防冲工程设计提供参考依据。研究发现:防冲槽内,在无抛石或抛填任何均匀粒径的卵石时,总会存在一个过水流量Q_X使闸前至护坦末端的沿程流速基本呈正态分布且流速与流量正相关;当防冲槽内无抛石或抛填任何均匀或混合粒径的卵石时,都改变不了流速大小的分布规律。对于一个几何结构不变的消能工,消能防冲槽内无任何抛填物的工况下,其最佳消能能力是一个常数;当防冲槽内有抛填卵石时,任何流量都存在一个使其防冲槽消能效果最好的最佳粒径组合,在最佳粒径组合下的流速就是对下游破坏力最小的安全流速。     

水布垭水电站泄洪消能设计创新与实践

水布垭水电站消能区岩性软弱破碎,抗冲刷能力低。但岸边溢洪道最大泄量达18 320 m3/s,泄洪落差171 m,最大泄洪功率31 000 MW。致使泄洪消能技术难度居国内外同类工程之首,其具体表现在:①消能区方案选择难;②消能区防护方案选择难;③冲淤形态控制难;④防淘墙结构设计难;⑤防淘墙施工难。通过系统的科学试验和技术攻关,首次提出防淘墙防护方案;独创新型消能工布置形式和综合防冲结构措施。工程建成后,经过了最高运行水位的考验。对同类工程设计具有很好的参考作用。     

裙板消能工设计中应注意的几个问题

根据裙板消能工的防冲试验研究成果,结合新疆若干引水防沙枢纽工程实际,针对泄洪冲砂闸与防冲裙板的不同连接、布置形式,分析了在计算冲坑深度时相关参数的合理取值问题;对确定闸后防冲隔墙、两岸导流墙等结构的基础埋置深度以及埋设范围等提出了建议;对如何控制闸后下游水位、提高裙板消能效果的措施等进行了分析、探讨。     

胜利油田海岸蚀退与防治工程技术研究

在胜利油田海岸蚀退与防治的工程措施中,要重点把握宏观蚀退和微观保护、消浪和消流、顺坝和丁坝、保滩与护脚、防冲与促淤的关系.在油田现状下,海岸防护的目的是在宏观蚀退的条件下保护沿岸地区工程安全,工程措施不能在宏观上改变海洋和地质条件,而能在局部改善水沙条件.在消浪的同时应注意切断顺岸流才能减小局部的冲刷,采用顺坝与消浪丁坝截流结合起来的工程措施能取得更好的防冲效果.消浪方式用潜堤或透水堤形式为宜.护脚的前提是保滩,保滩的手段是消浪,在防冲和促淤之间应以防冲为主要目的.     

大藤峡水利枢纽工程消能防冲优化试验研究

大藤峡水利枢纽工程消能防冲设计优化是初步设计阶段重点关注的问题之一,通过大藤峡水利枢纽工程消能防冲水工断面模型试验,对初设阶段大藤峡泄洪消能建筑物方案消能防冲效果进行试验研究,分析消能防冲设计方案可能存在的问题,并对消能防冲方案进行优化试验,提出了适宜大藤峡枢纽工程水流条件的消能工型式,确定了最优的消能工体型参数。     

毛阿提引水枢纽分水排沙试验研究

为研究毛阿提引水枢纽上下游冲淤演变状况及消能防冲效果,对毛阿提引水枢纽设计方案进行了系列动床试验,试验测定了各典型流量下枢纽上、下游河床、整治段冲淤演变情况,冲淤变化历时、冲淤范围和冲刷深度。结果表明:毛阿提引水枢纽总体布置基本合理,消能防冲效果良好。根据试验结果,给出了实际运行中的各个闸门的运行方式,供运行管理单位调度方参考。更多还原     

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.