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二期横向围堰用以截断长江主河床,迫使长江水流从导流渠宣泄。二期上下游横向土石围堰与纵向混凝土围堰共同形成二期基坑(见图1),为大坝泄洪坝段和左岸厂房坝段及厂房创造干地施工条件。上游横向围堰最大高度82.5m,形成的库容达20f乙m’,实属长江干流上的一座大型土石坝。围堰填筑最大水深达60m,最大档水水头达85m,防渗墙最大高度74m,在国内外围堰工程中均属罕见。上下游横向土石围堰轴线总长达2438m,高60-80m,土石方填筑总量达1060万m’。混凝土防渗墙总面积9.22万m‘,高压旋喷墙0.对万m‘,墙底基岩强透水带灌浆1.门万m… 相似文献
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景洪电站二期上、下游围堰土石方填筑量共计约111.21×104m3,国内同等规模项目完成的施工时间不少于5个月,因景洪水电站要提前于2005年1月底截流,要求二期上、下游围堰于2005年5月底施工全部完成,要求围堰堰基的高压喷射防渗墙施工从2005年2月初到3月底完成,这表明二期围堰基础防渗墙施工的工期十分紧迫,急需在工地现场进行围堰防渗高压喷射试验,通过试验为后续的正式施工选定各类技术参数。文章详细介绍了试验情况。 相似文献
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由于受现场地质条件约束,二期汛期围堰下的防渗结构设计不能保证主体工程在干地施工;并且为满足合同工期的要求,二期汛期围堰在2013年6月之前的填筑强度高(汛前必须填筑至505 m高程),二期汛期围堰与两道防渗墙施工的干扰大。为了更好的发挥上游防渗墙的挡水防渗效果,将位于二期汛期围堰下的防渗墙优化上移至二期枯水围堰下,并在防渗墙顶部和临时围堰内侧边坡填筑粘土料,与汛期围堰的防渗土料相连形成封闭的防渗体系,为河床芯墙坝主体工程汛期施工创造有利条件。 相似文献
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石头河坝体填筑于1976年6月开始,1982年竣工。共完成土石方填筑835万立方米,其中土料183万立方米,石料614万立方米,反滤料38万立方米。土料场分布于坝址上下游附近1.5公里的鸡坡、温家山、双家山三个料场,总储量约1200万立方米。砂石料场分布于坝址上下游7~8公里 相似文献
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吕长涛 《河南水利与南水北调》2016,(3):72-73
南水北调高填方渠堤一期分区填筑,各层土料填筑碾压试验,料场井字形分区分层开挖集料,Ⅱ区与Ⅲ区土料同步填筑上升,渠堤碾压,一期与二期接触面削坡开蹬,二期分区填筑,Ⅰ区、Ⅱ区与Ⅲ区土料同步填筑上升,渠堤碾压与边坡修整。 相似文献
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鲁布革电站堆石坝防渗体原选用下游红土料与风化白云岩的掺合料,由于运距远,土料含水量高,施工难度大且不经济。后取风化料作室内物理力学试验,并经现场29场碾压试验,确定了风化料作高土石坝防渗体的施工工艺流程和主要施工参数。1986年2月用于坝体一部分的高水围堰施工中,用风化料填筑围堰斜墙9.37万m~3,1987年主坝心墙风化料填筑8.09万m~3,填筑高度约34m。 相似文献
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三峡工程大江截流及二期围堰设计 总被引:1,自引:0,他引:1
长江三峡工程施工导流采用“三期导流、明渠通航”方案。二期施工围左岸,进行主河床截流,长江水流从导流明渠宣泄,二期上下游横向土石围堰与纵向混凝土围堰共同形成二期基坑。大江截流采用上游单戗堤立堵方案,大江截流水深60m,截流流量14000m3/s~19400m3/s,抛投强度平均达5.21万m3/d。上游横向围堰最大堰高82.5m,库容20亿m3,围堰填筑最大水深60m,最大挡水水头达85m,防渗墙最大墙高74m。上下游横向围堰土石方填筑总量达1032.1万m3,混凝土防渗墙总面积8.345万m2,要求截流后一个枯水期将围堰填至度汛高程。 相似文献
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长河坝水电站左右岸边坡开挖与围堰填筑同步进行,由于料场不具备开采条件,围堰填筑石料料源紧缺,根据招标文件和施工实际情况,坝肩高边坡开挖料均需要用于围堰填筑,但150~250 m高边坡开挖翻到河床的石料能否用于围堰填筑使用必须经过试验研究论证。通过长河坝水电站工程围堰填筑石料利用高边坡开挖滚落石料的试验研究和工程应用实例分析,论证了围堰填筑石料可利用高陡边坡开挖滚落石料的可行性及其工程措施与应用特性。 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