超大U型薄壁渡槽造槽机施工技术在湍河渡槽工程中的应用

南水北调湍河渡槽工程为相对独立的三线三槽40m跨的双向全预应力结构U型薄壁渡槽,槽身混凝土等级为C50W8F200。渡槽槽体结构新颖,受力复杂,结构尺寸及施工技术较为复杂。该工程通过造槽机机械化施工方法,该施工方法基本不受汛期及极端天气影响,可全年施工,大大缩短了工程工期,同时,节省了工程结构成本及施工投资。     

高性能混凝土在樟洋渡槽施工中的应用

樟洋渡槽槽身采用现浇U形薄壳后张预应力混凝土结构,混凝土强度标号高,槽身壁薄,对混凝土的性能要求很高,为了保证渡槽的施工质量,工程项目部聘请了国内混凝土专家对高性能混凝土进行了专题的技术攻关,最后选定混凝土的最佳配合比。     

旗岭现浇混凝土拱式渡槽施工方法及质量控制

东深供水改造工程B—I标旗岭渡槽是东改工程的标志性建筑物之一，采用大跨度拱肋支承、现浇预应力混凝土U型薄壳槽身，技术含量高、施工难度大，为国内首创，着重介绍旗岭渡槽拱肋和槽身的施工质量方法和施工控制。     

张峰水库林村河渡槽混凝土施工技术简述

林村河渡槽是张峰水库工程中跨度最长、高度最高的一座渡槽,介绍了林村河渡槽的工程概况,阐述了该渡槽下部的基础、墩帽、拱圈和排架等结构,以及上部的槽身和栏杆等结构混凝土工程的施工方法,以期为其他渡槽混凝土工程施工提供借鉴。     

大流量大跨度预应力渡槽支架法现浇施工技术

南水北调中线干线工程贾河渡槽设计流量大、结构跨度大,单体槽身自重约3600t,其结构复杂程度与施工技术难度国内罕见。本文重点介绍了贾河渡槽槽身模板及模板支架的设计与施工,以及槽身混凝土与预应力施工技术,较系统地反映了贾河渡槽支架法现浇施工技术的实际应用情况,供同行在同类工程施工中参考。     

孟楼渡槽槽身三向预应力施工工艺

鄂北地区水资源配置工程孟楼渡槽槽身采用三面环向预应力结构,为避免混凝土产生裂缝,提高渡槽的抗裂性能和整体刚度,在进行三向预应力施工时,制定详细的施工工艺流程与质量控制方案,确保了渡槽槽身工程质量,同时还节省了大量钢材,在一定程度上提高了渡槽的耐久性。     

泵送混凝土在30m跨渡槽槽身施工中的应用

以漕河渡槽槽身三向预应力混凝土施工为例,介绍泵送混凝土施工在渡槽工程的具体实施情况。高架现浇三向预应力渡槽采用泵送混凝土在国内经实践检验,效果良好,保证了混凝土入仓强度,为大型渡槽混凝土施工积累了一定的经验.     

满堂支架法现浇U型薄壁渡槽施工技术

U型现浇渡槽槽身预应力钢筋混凝土薄壁结构的施工是槽渠建筑物施工的难点。本文重点介绍了普沙渡槽U型薄壁槽身现浇混凝土的施工,以及预应力施工技术,较系统地反映了普沙渡槽满堂支架法现浇混凝土施工技术的实际应用情况,为今后同类工程施工提供了参考借鉴。     

漕河渡槽槽身混凝土防裂研究

分析了南水北调中线干线工程漕河渡槽在工程施工初期槽身产生裂缝的原因,产生裂缝的原因为：混凝土内外温差大;混凝土自身结构约束及自重应力大;施工过程中混凝土养护不到位等。通过优化混凝土配合比、选用高效减水剂、优化骨料级配等技术手段控制渡槽槽身混凝土裂缝的产生。     

旗岭渡槽施工方法及控制

东深供水工程B—I标旗岭渡槽是东改工程的标志性建筑物之一。工程采用大跨度拱肋，现浇预应力混凝土U型薄壳结构槽身，技术含量高、施工难度大，是东改供水改造工程重大技术课题之一，为国内首创。文章介绍了旗岭渡槽的施工方法和施工控制。     

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。     

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.     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。