京密引水渠龙山所管段渠道混凝土衬砌板冻胀分析

京密引水渠:A2005年开始渠道低水位运行,平均水深1.5m,低于冬季输水设计水深(1.0～1.2)m,造成部分现浇混凝土板冻胀隆起、断裂、滑落.从2005年至2006年冬季输水结束,渠道阴坡现浇混凝土板破损长度1万6878m,占龙山所管段渠道总长度的45.57%;阳坡现浇混凝土板破损长度4753m,占龙山所管段渠道总长度的12.83%.针对渠道衬砌破坏现状,结合京密引水渠一期技术改造工程设计方案、渠道混凝土衬砌冻胀破坏现状,冻胀观测情况,以及对渠道在冬季低水位运行时,部分混凝土衬砌板冻胀破坏情况从设计、管理运行等方面进行分析,并总结经验教训.     

东港灌区铁甲北五支渠道衬砌方案比选

针对铁甲北五支渠道断面淤积,杂草丛生,输水能力低下,渗漏等现状,对对渠道采用现浇混凝土板衬砌。文中通过3种衬砌方案比选,最终决定采取梯形渠道衬砌。     

台兰河项目渠道衬砌型式比选

考虑到渠道沿线土质、气温、地下水位、建材来源、渠道流量及便于施工等因素,台兰河项目渠道衬砌型式设计将弧形渠底及边坡下部采用干砌卵石灌浆、边坡上部采用现浇混凝土板衬砌梯形断面方案作为工程实施推荐方案。     

南水北调东线鲁北小运河高水位输水河段防渗衬砌设计

文章结合南水北调东线一期工程鲁北段小运河工程线路特点,以渠道防渗、防冻胀、防扬压为控制目标,以现浇混凝土衬砌板质量和渠道排水减扬压系统为关键技术,综合考虑地理位置、水文气象、地质条件、机械化施工等因素,确定高水位输水河段衬砌结构型式。该型式可满足机械化衬砌的要求,且各项功能指标均达到了设计预期。     

可发性聚苯乙烯发泡板在博斯腾湖东泵站输水干渠的应用

博斯腾湖东泵站输水干渠工程属于新疆塔河综合治理项目，工程位于孔雀河上游，博斯腾湖西泵站以东，接博斯腾湖东泵站出水池末端，全长39．28km，渠道设计流量为45m^3／s，加大流量54m^3／s。桩号0＋000～13＋650为混凝土衬砌渠道，其中，桩号0＋000～9＋347渠底为现浇混凝土板，边坡为混凝土预制板，混凝土板下用聚苯乙烯苯板垫层防渗抗冻，9＋347～13＋550为全段面预制混凝土板衬砌，13＋550～13-650为现浇混凝土板，渠底宽20m，渠深3．11m，上口宽为30．94m；     

南水北调中线工程大型渠道混凝土施工方案选择

南水北调中线工程总干渠是特大型输水建筑物,渠道具有设计里程长、断面尺寸大、混凝土衬砌强度高及平整度要求严格等特点,选择合适的衬砌施工机械对保证混凝土衬砌施工质量及混凝土高强度施工十分重要。结合南水北调中线工程渠道设计特点和施工要求,通过比选,推荐渠道衬砌机施工作为南水北调中线工程渠道混凝土衬砌的施工方案。     

新型斜坡衬砌机的施工维护与保养

<正>南水北调东线一期山东段渠道工程长约300 km,设计采用混凝土现浇,承担输水、行洪及排涝任务。渠道衬砌如何快速保质保量完成是施工的重大挑战。国内最新研制的大型渠道斜坡衬砌机是一种新型的渠道衬砌施工设备,这种设备无论从施工效率、质量控制、平整度及衬砌维护等各方面都优于人工衬砌,目前正逐渐代替人工衬砌护坡,应用较为广泛。     

大型输水明渠混凝土机械化衬砌施工技术研究

南水北调中线榆水明渠渠道混凝土采用机械化现浇衬砌施工技术,弥补了此前大型输水渠道混凝土衬砌中生产效率低、资源浪费和施工质量欠佳等缺陷,有效提高了施工进度和工程质量,同时节约了施工成本.该文结合漕河明渠现场施工情况,介绍了渠道混凝土机械化现浇衬砌施工工艺和方法,对其优缺点进行了总结.     

不同渠道衬砌形式防渗效果试验

以中国西部地区某灌区为例，在概述工程环境因素及运行工况的基础上，展开试验设计，提出6种渠道衬砌形式，采用动水法展开渠道输水损失计算；并对1个冻融期内各种衬砌形式的节水效果和投资效果进行分析，在综合比较节水效果和投资效果的基础上，确定出"现浇混凝土+保温板；砂浆+树脂油膏填缝"的最佳衬砌形式。     

恰木萨水电站输水渠道结构设计与基础处理

结合恰木萨水电站输水渠道工程地质条件,通过前期基础处理方案比选,根据现场开挖揭露出的实际地质情况,对输水渠道结构设计形式及基础处理做了优化和调整,确定输水渠道采用梯形横断面、现浇C20混凝土衬砌、两层两布一膜防渗的结构形式,基础处理采用换填砂砾石,粉土厚度小于10 m全部挖除并换填砂砾石,粉土厚度大于10 m只挖除10 m厚粉土并换填砂砾石。目前,该设计方案正在实施中。     

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.