高速水流溢流面抗冲耐磨新材料应用研究

水工泄水建筑易遭受高速水流和含砂水流冲磨和空蚀破坏问题多年来一直未能得到很好解决。该文针对洪口水电站大坝溢流面最大流速近43 m/s,应用研究HF高强耐磨粉煤灰混凝土专用外加剂配置高性能、自密实、抗冲耐磨的护面混凝土,成功解决了碎卵石配置高抗冲耐磨混凝土的技术难点,可供类似工程参考。     

高抗冲磨橡胶混凝土在前坪水库导流洞的应用

高抗冲磨橡胶混凝土将废旧轮胎橡胶颗粒掺入混凝土,与普通混凝土相比强度较低,但抗裂性能、抗冻性能和抗冲磨性能显著提高,是一种低强度高性能、环保节能的新型建筑材料。为考察高抗冲磨橡胶混凝土在泵送情况下的抗冲磨性能、施工性能以及服役期间的耐久性能等工程应用技术问题,在前坪水库导流洞工程洞身出口及消力池段进行了原型应用试验,结果表明,高抗冲磨橡胶混凝土在泵送条件下和易性较好,施工工艺简便,抗压、劈拉强度满足工程要求,尤其是抗冲磨强度大幅提高,可为其在水利工程中的推广应用提供工程参考。     

富春江水电站溢流面混凝土 抗冲磨防护试验

针对富春江水电站溢流面的运行条件,采用SK抗冲磨刮涂聚脲和SK高韧性环氧耐磨防护涂层对其抗冲磨性能进行了室内试验研究,并在现场选择1#～4#孔进行了溢流面混凝土表面抗冲磨防护试验,经历了多次泄洪的考验。实践证明,这两种柔性抗冲磨防渗涂料具有抗冲耐磨、抗紫外线能力强、能适应在潮湿环境下施工以及施工简单的特点,对溢流面混凝土的抗冲磨防护效果很好。     

SK-PAM特种抗冲磨树脂砂浆材料工程特性研究

本文针对目前常用的薄层抗冲磨防护材料难以抵抗高速水流推移质磨蚀破坏难题,以柔性氨基树脂材料和特种固化剂为胶结体系,添加抗冲磨填料,研发了一种新型抗冲磨树脂砂浆材料。并对新型树脂砂浆进行了力学性能、冲磨能力和环境适应性试验,试验结果表明砂浆伸长率在5%以上,与基面黏接强度大于2.5MPa,表明其具有良好的抗裂能力和适应变形的能力;水下钢球法冲磨试验3个周期质量基本没有损失,同等条件下圆环法冲磨对比试验证明其抗冲磨强度是高强环氧砂浆的5倍以上,证明新型抗冲磨树脂砂浆具有高弹韧性的材料特性,适用于泄水建筑物的抗冲磨、特别是推移质破坏的防护和修复。     

中国水工结构抗冲磨防空蚀涂料的研究及应用现状

总结了影响水电工程冲磨损坏的影响因素和水电工程结构抗冲磨防空蚀的材料种类，重点介绍了抗冲磨防空蚀涂料的耐磨性能试验方法及其影响因素、抗冲磨防空蚀涂料的种类及其应用情况，陈述了环氧耐磨涂料、聚脲耐磨涂料和耐磨混凝土的性能差异和性价比。结果表明：影响水工结构冲磨损坏的因素主要为水的冲磨角度、水的流速、悬移质颗粒大小和悬移质的含量等；用于水工结构的抗冲耐磨涂料主要为环氧树脂涂料和聚脲类涂料；影响涂料本身耐磨性能的因素为树脂的弹性和硬度、填料的种类、微米级填料的硬度和含量等；抗冲耐磨涂料主要用于水电工程排沙洞、泄洪洞和溢流面等。     

超高性能混凝土抗冲磨性能试验研究

针对新疆水利工程抗冲磨部位应用的抗冲磨混凝土冲磨破坏问题,采用混凝土抗压强度试验及水下钢球法对超高性能混凝土(UHPC)的抗冲磨性能等进行试验研究,同时与普通硅粉混凝土、HF抗冲耐磨混凝土的抗冲磨性能进行对比研究,结果表明:UHPC具有极高的力学性能,28 d抗压强度可以达到130.59 MPa,抗冲磨性能明显提高,抗冲磨强度是普通硅粉混凝土的4倍以上;UHPC具有极高的流动性,具有自流平效果,兼备良好的施工性能。     

彭水水电站抗冲耐磨混凝土配合比设计与性能试验研究

通过对抗冲耐磨混凝土配合比进行的设计与性能试验研究,所设计的抗冲耐磨混凝土配合比的力学性能、抗冻、抗渗及抗冲磨性能均满足设计要求.     

水工泄水建筑物抗冲耐磨高分子护面材料综述

水工泄水建筑物受高速夹沙水流冲刷及推移质撞击冲磨,是水利水电建设中有待解决的重大问题。结合实例阐述了现有高分子护面材料在水工泄水建筑物抗冲耐磨保护中的应用及研究动态,分析了聚合物砂浆、喷涂弹性体、耐磨涂料各自的优缺点。指出新型纳米耐磨涂料是抗冲耐磨护面材料的一个重要发展方向,讨论了其在水工泄水建筑物上应用需要解决的关键技术问题。介绍了一种能经受40 m/s流速的新型纳米抗冲磨面层涂料的制备方法,经高速圆环法试验表明,具有优异的抗冲磨性能。     

环氧树脂材料在冲砂底孔防护中的应用

鉴于冲砂底孔受高速挟沙水流的冲刷及推移质的撞击冲磨,危害冲砂底孔安全运行,阐述了环氧树脂材料在冲砂底孔抗冲耐磨保护中需要解决的关键技术问题,可供类似条件下的抗冲耐磨防护提供借鉴。     

糯扎渡水电站左岸泄洪洞混凝土裂缝处理

糯扎渡水电站左岸泄洪洞底板及边墙4.5m高范围为C_(90)55抗冲磨混凝土。由于抗冲磨混凝土设计强度高、胶凝材料用量大、水泥水化热温升高、混凝土温控难度大,加之施工前期使用的水泥早期水化速度快、发热量大,施工中虽按设计要求采取了温控措施,但底板及边墙抗冲磨混凝土仍出现了一些裂缝。左岸泄洪洞设计泄洪流速最大达47m/s,底板及边墙混凝土的防空蚀、抗冲耐磨要求高,其安全运行问题突出。为此,对抗冲磨混凝土出现的裂缝采用化学灌浆施工技术进行了处理。     

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。     

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。     

Desiccation and recolonization of phytobenthos in a regulated desert river: Colorado River at Lees Ferry,Arizona, USA

We tested the recolonization of the phytobenthic community in the tailwaters of Glen Canyon Dam following long- and short-term experimentally induced desiccation. The response of Cladophora glomerata, Oscillatoria spp., miscellaneous phytobenthos species and periphyton was studied over 18 weeks using three treatments: (1) undisturbed control cobbles from the submerged zone; (2) cobbles desiccated and replaced into the submerged zone; and (3) cobbles desiccated and replaced into the varial zone. Periphyton density and compositional response resulting from these treatments were also examined. Desiccation treatments were significantly different in biomass from controls throughout the study. The biomass of desiccated and replaced river cobbles averaged <30% of the controls for C. glomerata and periphyton during the 18-week recolonization period. In contrast, the biomass of the control Oscillatoria and miscellaneous phytobenthos species averaged only 3 and 50% of that in the desiccation treatments, respectively. Cladophora, the dominant alga, comprised 77% of the phytobenthic biomass. A significant positive relationship between discharge, Cladophora and periphyton biomass was present in all treatments, while there was a negative relationship with discharge for Oscillatoria and miscellaneous phytobenthos species. There was a significant inverse correlation, as well as a pattern of separate biomass dominance, between C. glomerata and Oscillatoria. Cladophora was the dominant phytobenthos species on cobbles below the baseflow and Oscillatoria was dominant on cobbles in the varial zone. In general, the Cladophora biomass decreased under intermittent drying conditions, while Oscillatoria declined under permanently wet conditions. Diatom composition was not significantly different between treatments; however, their density was lower on desiccated cobbles. Diatom density on desiccated cobbles in the submerged and varial zones averaged 69 and 42% of that of the controls, respectively. Recovery and maintenance of benthic resources are hindered by fluctuating flow regimes driven by electricity and irrigation requirements. Repeated desiccation of the phytobenthos has major effects on the bottom-up interactions in the Colorado River ecosystem. © 1998 John Wiley & Sons, Ltd.