共查询到20条相似文献,搜索用时 46 毫秒
1.
南阳回龙抽水蓄能电站上库碾压混凝土大坝浇筑完工后不久,在上游迎水面发现有5条裂缝。裂缝产生原因有3方面,即设计、材料和施工。经研究决定采取化学灌浆方法处理裂缝。介绍了化学灌浆的工艺流程和施工方法。大坝处理后达到设计要求。 相似文献
2.
混凝土大坝在施工和运行过程中因为各种原因均会出现裂缝,裂缝将严重影响大坝的安全稳定性。观音岩右岸大坝28~30号坝段1 045.0~1 047.0 m高程盖重混凝土浇筑完成后,在进行固结灌浆时,由于坝基地质条件比较复杂,浆液顺岩体裂隙串通,将盖重混凝土顶裂,影响大坝后续施工。在分析产生裂缝的原因后,确定采取化学灌浆措施处理裂缝。详细介绍了化学灌浆施工工艺及质量控制措施,可供类似工程借鉴。 相似文献
3.
唐河水电站大坝地处山西省灵丘县,该大坝沿坝轴线从左到右依次为重力坝段、泄洪闸段和混凝土面板堆石坝段,混凝土面板施工完毕后局部出现了裂缝现象,组织进行了裂缝处理,采用了"内填外堵"的处理方案。文中介绍了裂缝处理的施工流程、工艺、材料性能及施工注意事项。 相似文献
4.
紫坪铺大坝混凝土面板在5·12地震中遭到破坏。在面板震损部位的处理施工中,采取了合理的技术措施,采用了合适的修补材料。处理后的检查结果和运行效果表明,本次震损裂缝处理是成功的,确保了大坝的安全运行。 相似文献
5.
6.
在皂市水利枢纽大坝工程垫层高程61.5 m处经现场检查,发现有若干条深度、宽度各异的混凝土裂缝.为了处理好这些裂缝,对裂缝的分布情况,产生原因进行了分析,并按设计要求进行了现场化学灌浆试验.通过试验确定施工参数,制定垫层混凝土裂缝化学灌浆处理的施工技术方案,指导垫层混凝土裂缝化学灌浆处理的施工.钻孔检查表明,处理效果良好. 相似文献
7.
8.
受混凝土自身凝固特性、施工环境、混凝土浇筑过程中施工组织、气候变化等等因素的影响,以混凝土为主材浇筑的大坝经常会出现各种裂缝。针对混凝土大坝坝体裂缝的危害,提出了以聚氨酯类灌浆材料进行裂缝处理,具体以汾河二库大坝为例进行了阐述。 相似文献
9.
徐凯 《河南水利与南水北调》2021,50(3):45-47
水库大坝面板混凝土受到施工工艺、环境温度以及养护管理等要素影响,会产生不同程度裂缝.在裂缝处理中,处理方案编制要注重参照裂缝分布特征以及分布成因,提升方案实施针对性与有效性,在实践中对方案适度改进.文章对思南县沙坝水库大坝混凝土面板裂缝处理方案进行探析,在分析工程概况基础上,提出面板施工与裂缝处理措施.还拟定对应的处理... 相似文献
10.
介绍了张峰水库大坝垫层混凝土施工中为了预防混凝土裂缝的出现,采取了合理、科学的设计及施工措施,在裂缝控制上取得了良好的效果,保证了混凝土结构物安全、正常、有效地运行。 相似文献
11.
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
12.
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
13.
14.
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
15.
16.
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
17.
18.
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.
__________
Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
19.
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