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本文详细介绍了凌津滩水电站工程坝顶门机轨道梁预应力锚索的施工工艺和方法,对锚索张拉及后期预应力损失进行了综合分析。 相似文献
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在斜拉桥和支墩坝结构的基础上,构建了一种新的“预应力锚索斜拉坝”坝型。该坝型由布置在坝面上游侧的三角形混凝土锚碇墩、预应力斜拉锚索和混凝土挡水坝体组合而成,通过预应力斜拉锚索,预先对挡水坝体施加应力,形成地基、锚碇墩和预应力锚索对挡水坝体的锚拉作用,水库蓄水后依靠挡水坝体与锚碇墩、预应力锚索系统共同作用来维持坝体稳定,并改善坝体的应力状态。该坝型具有工程量省、受力比支墩坝更为合理、能够充分利用材料工程特性等优点,是建设300 m级高坝很有竞争力的一种坝型,具有良好的发展远景。 相似文献
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二滩水电站坝顶门机自重和运行荷载大,承担着底孔和中孔事故检修闸门运行启闭的任务,鉴于中部坝段坝顶布置有泄洪表孔,为了门机轨道布置的需要,在表孔闸墩间以预制混凝土大梁相连接,这些轨道下的大梁的承重要求也相应较高。二滩坝顶门机轨道梁大量采用了后张预应力锚索,有利于施工,解决了一些结构上的难题,同时也取得了一些设计和施工经验。 相似文献
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水口水电站在溢流坝闸墩,坝顶门机梁及启闭机梁等部位采用了预应力锚固技术。本文介绍了预应力锚固的设计及施工工艺,并通过对观测资料的分析,评价其设计的合理性。 相似文献
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本文主要论述了某水电站坝顶门机轨道梁的施工技术.在保证工程质量的前提下,优化施工技术方案,能够提前完成施工任务.文章通过对预应力混凝土梁的预制场地布置和安装措施分析研究,总结出了水电站坝顶门机轨道梁优越的施工技术.类似工程可参考借鉴. 相似文献
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我国很多大坝为二十世纪50、60年代兴建的,三类坝情况十分严重。在混凝土坝中,基岩断层裂缝对结构安全构成严重威胁,工程实例说明,预应力锚固和止滑重力墩以及高压固结灌浆不失为基岩断层裂缝补强加固的有效措施。本文简述了预应力锚固的施工方法和程序。 相似文献
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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。 相似文献
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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. 相似文献
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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. 相似文献
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V. K. Konovalov O. V. Yashkin V. V. Ermakov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2008,42(2):105-109
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.
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Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
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Peter B. Bayley 《河流研究与利用》1991,6(2):75-86
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. 相似文献
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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。 相似文献