无轨滑模在溢洪道混凝土面板施工中的应用

本文结合具体实例详细介绍了无轨滑模溢洪道混凝土面板的施工工艺、操作方法及质量控制要点。采用无轨滑模溢洪道混凝土面板施工工艺简化了模板结构,节省了轨道材料,降低了模体重量,具有工艺简单、使用便捷、施工速度快、造价低、观感优良的优点,取得了良好的社会效益和经济效益。     

面板堆石坝无轨滑模的设计与制造

<正>重庆桃子沟水库大坝结构是钢筋混凝土面板堆石坝,最大坝高60.6m。桃子沟水库堆石坝在面板混凝土浇筑之前,工程技术人员结合本工程具体特点先后提出采用有轨滑模和无轨滑模施工技术浇筑面板混凝土两种方案,经过反复论证两种方案的优缺点后,最终确定了无轨滑模施工方案。无轨滑模不需要增加复杂的轨道行走机构,利用侧     

黄河苏只水电站厂房尾水渠底板采用无轨滑模施工方法的介绍

苏只水电站厂房尾水渠底板混凝土采用无轨滑模施工,利用侧模板代替轨道,简化了程序,节省了材料,缩短了工期,避免了轨道架设的繁琐.具有造价低、使用方便、施工速度快、质量好的优点,是值得推广的施工技术.     

面板堆石坝混凝土面板滑模设计与施工

以往，在面板堆石坝施工中使用有轨和无轨两种滑模技术。通过改进设计和附属设备，取消轨道，从而将有轨滑模变为无轨滑模。实践表明，这一改变不仅不影响滑模的使用功能，而且能节省费用，加快施工进度。     

伊朗塔里干水利枢纽工程溢洪道底板混凝土浇筑滑模设计与施工

伊朗塔里干水利枢纽溢洪道工程泄槽底板混凝土浇筑,采用跨度17.1 m无轨面板滑模施工,取得了很好的效果,该滑模设计和施工特点,可供同类工程借鉴。     

苗尾水电站溢洪道控制段混凝土施工技术

苗尾水电站溢洪道控制段混凝土工程是电站的关键性控制工程,施工工期紧,施工条件差,质量标准要求高,因此,采取科学的施工技术至关重要。控制段溢流堰采用长臂反铲挖掘机辅助门机入仓,台阶法浇筑施工;闸墩采用门机辅助皮带机入仓,台阶法浇筑施工;闸室溢流面采用皮带机入仓,无轨滑模浇筑施工。通过以上施工技术,控制段混凝土工程提前1个月完成施工,施工质量达到优良水平,同时为金属结构安装预留足够的工期,也为实现电站安全度汛和下闸蓄水创造了必要条件。施工经验值得同类工程借鉴。     

坡面底板有轨滑模浇筑技术的应用及改进

糯扎渡水电站溢洪道底板设计最大流速为52 m/s,为防止空蚀现象发生,要求底板表面平整度达到3 mm/3 m。为解决这一难题,提出采用有轨滑膜系统,在施工过程中发现原设计滑膜系统中布料桁架自身笨重、轨道重复利用率低、牵引系统操作难度大、滑膜搬运困难等问题。结合原有轨滑模系统布置及运行情况,分析现场发现的问题,对布料桁架、轨道、牵引系统等方面的设计进行改进,改进后的滑模浇筑系统运行更方便快捷,可有效节约成本、提高利润。     

滑模技术在糯扎渡水电站溢洪道抗冲耐磨混凝土中应用

糯扎渡水电站溢洪道泄槽段底板混凝土处于高流速区,对混凝土浇筑质量要求极高,为保证底板抗冲耐磨混凝土施工质量和外观质量,陡槽段23％坡段底板和掺气坎反坡段主要采用滑模技术进行施工.文章详细介绍了滑模系统的组成、极限承载校核以及滑模施工时应注意的问题.经检测,该底板混凝土施工质量达到优良.     

洞巴水电站溢流堰施工技术

洞巴水电站溢洪道溢流堰的混凝土浇筑使用轻型桁架模板.在浇筑溢洪道溢流堰不规则圆弧段混凝土施工中,提出质量缺陷的补救对策,以供同行参考.     

清河水库溢洪道闸墩混凝土滑模施工工艺

滑模施工具备节省时间、经济、成本低、外观质量好等优点,目前滑模施工的液压设备、模板设计、加工等技术比较成熟,液压设备等生产比较规范,方便施工购置.本文结合辽宁清河水库除险加固工程溢洪道闸墩混凝土滑模施工,从方案选择、施工布置、滑模设计、制作、安装、拆除、混凝土运输、浇筑、降温、保温等方面介绍了混凝土滑模施工工艺,供大中型工程施工借鉴.     

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。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

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.     

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.     

Impacts of Microcystis on algal biodiversity and use of new technology to remove Microcystis and dissolved nutrients

Cyanobacteria often dominate eutrophic lakes, outcompeting green algae that are required by fish and zooplankton. This study was undertaken to ascertain the impact of the cyanobacterium, Microcystis, on algal biodiversity. Under laboratory conditions, we found that the presence of Microcystis decreased phyla richness by 58%, phyla evenness by 47%, genera richness by 66% and genera evenness by 51%. Analysis by mixed anova s demonstrated a significant interaction between treatment and time and confirmed a significant reduction in richness and evenness of phyla and genera. We also conducted a phosphate restriction assay on the algae in Mason Lake (Irvine, CA, USA) and found that the threshold needed for algal growth there was 0.02 mg L^?1 PO₄. A pilot study was then conducted to test the effectiveness of the Blue Pro? water treatment facility in removal of this colonial organism from Mason Lake, in addition to removal of dissolved nutrients required for its growth. We measured a 97% reduction in Microcystis cells, a 72% reduction in chlorophyll‐a, and a 96% reduction in phosphate after just one 10 min cycle through the unit. Our study demonstrated that removal of Microcystis colonies may allow green algae to increase in numbers. This may improve algal biodiversity, which will benefit zooplankton and fishes.     

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。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

簸箕李引黄灌区水沙分布及优化调度的经验

灌区利用水沙观测所取得的资料和试验数据，运用水沙运动力学理论，总结分析和揭示了灌区水沙分布的规律和特点。在此基础上，结合灌区的实际运行情况，围绕减少骨干渠道的淤积进行探讨、研究，进而，优化水沙调度方案。该方案实施后，骨干渠道减旅伴效果明显，取得了成功的经验。     

小湾水库大坝防渗面板及其裂缝的加固处理

小湾水库大坝防渗面板整体抗渗性能差,且存在多条裂缝,通过对面板钢丝网喷涂丙乳砂浆加固处理及其裂缝修补,大坝渗漏量明显减少,且左岸上灌浆廊道内及大坝下游坝面92～93 m高程下廊道入口处原有小股射流全部消失.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.