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于景波 《河南水利与南水北调》2016,(2):67-68
入仓方式是碾压混凝土施工方案的重要环节,直接影响工程的施工进度和施工质量。文章对国内百米以上的碾压混凝土重力坝的入仓方式进行了统计,叙述了各种常用入仓方式的适用范围。根据官地大坝右岸的实际情况,对高速深槽胶带机配合塔带机入仓方案、高速深槽胶带机入仓+仓内自卸汽车转料、负压溜槽方案、满管溜槽方案、自卸汽车直接入仓方案以及下部自卸汽车直接入仓+上部满管溜槽入仓等方案进行了比较,决定采用自卸汽车直接入仓方案。卸汽车直接入仓分为坝前入仓和坝后入仓,文章主要介绍了坝前入仓坝如何解决入仓道路跨越上游二级配防渗区以及入仓口的处理。官地大坝右岸碾压混凝土采用全部自卸汽车直接入仓的方式和坝前入仓的方式,有效的加快了施工进度,保证了施工质量,值得类似工程借鉴。 相似文献
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蔺河口水电站大坝碾压混凝土施工根据自身的特点,采用20t自卸汽车直接入仓、负压溜槽入仓及缆机入仓三种方式进行碾压混凝土浇筑施工,取得了良好的效果。文章针对碾压混凝土运输中20t自卸汽车直接入仓及负压溜槽入仓方式的选择和应用进行了重点的论述。 相似文献
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玛尔水电站拦河坝采用碾压混凝土重力坝,碾压混凝土施工方案是大坝快速施工的关键,直接影响到工程的工期和投资。该文根据工程地形地质条件和枢纽布置特点,结合施工导流规划和施工进度安排,拟定了多种碾压混凝土入仓手段,提出采用自卸汽车、负压溜槽、皮带机、布料机和缆机等方式入仓的施工方案,结合对典型坝段浇筑上升高度分析,结果表明所选施工方案是可行、合理的。 相似文献
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负压溜槽和深槽式皮带运输系统在江垭工程中的应用 总被引:1,自引:0,他引:1
江坯大坝是在狭谷中建设的碾压混凝土高坝,两岸地狭窄,山势陡峻,用常规方法难以满足中,上部混凝土高强度,大规模的运输要求。通过在左岸布置负压溜槽和深槽式高速皮带联合运输系统,解决了这个问题。实践表明,江垭大坝工程采用负压溜槽和槽式高速皮带运输方案是成功的,可供同类型工程在施工中借鉴。 相似文献
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广西平南水电站拱坝为全断面碾压混凝土双曲薄拱坝,最大坝高65 m,坝底宽27 m,坝顶宽6 m。大坝施工采用全断面碾压通仓薄层连续上升施工工艺,碾压层厚为30 cm;采用2台1×3 m^3和1台1×1.5 m^3强制式拌和机拌制混凝土,混凝土浇筑时低仓位采用自卸汽车直接运输入仓,高仓位采用负压溜槽转料入仓的方式和辐射式缆机入仓的方式。文章介绍了工程规划布置、碾压混凝土配合比及原材料、拌制、运输、碾压及养护等施工工艺,以及采取的VC值动态控制方法和碾压混凝土施工采取的温控措施,效果很好。 相似文献
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结合洞河水库枢纽工程的基本概况及其复杂的地形环境条件,为满足碾压混凝土顺利入仓浇筑,对安装规划方案、系统组成、性能参数设计以及荷载验算方法进行深入论证评估,分析两种方案的优缺点,选用负压溜槽与深槽式皮带运输机系统为本次施工方案,并对此系统施工工艺与常规施工方法的应用效果分析、实用情况进行介绍对比,结果表明,该方案有较好的实用效果,经济效益显著。 相似文献
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江娅大坝位于湖南省慈利县江垭镇。在施工中成功地使用了深槽皮带和负压溜槽运输混凝土,并创造了碾压混凝土斜层铺筑施工方法获得成功。 相似文献
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蔺河口水电站双曲拱坝碾压混凝土施工技术 总被引:4,自引:0,他引:4
蔺河口水电站拱坝为目前陕西省在建全国第三高的全断面碾压混凝土双曲薄拱坝,最大坝高100m,大坝施工采用全断面碾压通仓薄层连续上升施工工艺,碾压层厚为30cm;采用2座1×3m~3和1座1×1.5m~3强制式拌和楼拌制混凝土,混凝土浇筑时低仓位采用自卸汽车直接运输入仓,高仓位采用负压溜槽转料入仓的方式和辐射式缆机入仓的方式。施工中严格控制碾压混凝土配合比、原材料,及混凝土拌制、运输、碾压及养护等施工工艺,并采取了VC值动态控制方法和有效的碾压混凝土温控措施,取到了很好的效果。 相似文献
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介绍梨园水电站厂房混凝土入仓采用高速深槽式皮带机和负压溜槽联合输送系统,成功地解决了高山狭谷地区两岸陡峭、不利于修建汽车道路或水平运输距离较远等混凝土入仓运输问题。该系统工艺先进、简单,其设备占地面积小,输送快捷,设备费用低,维护方便,便于管理,减少了混凝土周转次数,提高了混凝土的入仓强度及其质量。 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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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. 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