井沟导渗在梓山村水库大坝渗漏处理中的应用

梓山村水库大坝为均质土坝,由于基础及坝体施工不良等方面的原因,长期以来,存在较为严重的渗漏,时刻危及大坝的安全.通过采用导渗井、沟,完善下游排水设施处理后,坝体浸润线降低了0.6～3.0m,安全隐患得以消除.实践证明,井沟导渗是一种技术简单,施工容易,投资较少,能有效降低坝体浸润线,改变渗流出口方向,提高下游坝坡抗滑稳定安全系数的土坝渗漏治理方法.     

井沟导渗在梓山村水库大坝渗漏处理中的应用

梓山村水库大坝为均质土坝，由于坝基处理及坝体施工等方面的原因，长期以来，存在较为严重的渗漏，危及大坝的安全。通过采用导渗井、沟，完善下游排水设施处理后，坝体浸润线降低了(0．6～3．0)m，安全隐患得以消除。实践证明，井沟导渗是一种技术简单，施工容易，投资较少，能有效降低坝体浸润线，提高下游坝坡抗滑稳定安全系数的土坝渗漏治理方法。     

四川安县土坝震损特征与浸润线对抗震能力影响的分析

通过对四川安县28座中小水库震后灾情调查发现,地震后,对土坝破坏主要表现在大坝的坝顶和上游边坡,下游边坡破坏现象较小,尤其在下游设有完好的排水棱体情况下,即便是下游边坡很陡时仍然完好无损,这就说明坝体浸润线对坝体抗震效果影响很大,因此最大限度降低坝体浸润线是提高土坝抗震能力的有效措施。     

王家厂水库大坝坝体充填灌浆施工浅谈

王家厂水库大坝系均质土坝 ,坝体填土杂乱 ,施工中碾压不密实 ,因此透水性大 ,坝体浸润线偏高 ,文章论述了坝体存在的问题 ,并总结了充填灌浆的灌浆方法和施工工艺。     

高压喷射灌浆技术在云南病险水库加固工程中的应用

云南病险水库普遍存在坝体和坝基渗漏严重的问题,以白鹤水库除险加固工程为例,探讨了高压喷射灌浆技术在大坝防渗加固中的应用及效果。水库防渗处理后坝体浸润线降低,下游坝坡原渗水潮湿现象消失,高水位时下游坝脚的渗水量也大幅减小,坝体和坝基的防渗性能明显改善。高压喷射灌浆技术适用范围广,施工简便灵活,质量检测方便,对其他病险水库的加固处理具有借鉴作用。     

龙须湖水库均质土坝防渗加固设计

龙须湖水库始建于20世纪50年代,水库大坝为均质土坝,由于清基不彻底、坝体填土压实度和渗透系数不满足规范要求,虽经多次加固,坝体和坝基仍渗漏严重。为此,采用坝体混凝土防渗墙与坝基帷幕灌浆相结合的加固方案进行防渗处理。经观测,加固后浸润线明显降低,防渗效果显著。对类似条件下防渗墙的设计、施工和管理积累了经验,具有一定的参考价值。     

刍议水库的安全管理问题

大坝安全监测是评价施工质量、验证设计并指导工程安全运行的依据。水库大坝存在的工程质量问题主要是坝基、坝体和绕坝渗漏问题及因渗漏使坝体浸润线抬高造成坝坡不稳的问题。要着重解决大坝的渗漏问题,应建立起一道完整、封闭、可靠的防渗屏障,使大坝安全稳定。     

石佛寺水库大坝渗流监测系统建设和渗流性状分析

石佛寺大坝为均质土坝,并且坝基地质基础条件不好,大坝运行中部分坝段存在坝基渗流严重和坝体浸润线过高的问题。因此,应建立大坝渗流监测系统,实时掌握大坝的渗流情况,以便为相关施工和管理提供科学依据,确保工程的安全和正常运行。     

澄碧河水库土坝混凝土防渗心墙运行观测分析

澄碧河水库于1958年至1961年完成土坝填筑,1966年装机发电。设计最大坝高70.4米,总库容11.3亿米~3,装机容量26,000千瓦。由于土坝施工中填筑了大量的风化砾石,水库蓄水后坝体渗漏严重,浸润线逸出坝坡,下游坡面大面积沼泽化,影响到坝体的稳定安全。1972年至1974年,采用在坝顶利用冲击钻造孔、泥浆下浇注混凝土防渗心墙的方案,对土坝进行了防渗加固。土坝及混凝土防渗心墙建成运行后,进行了渗流、沉陷、水平位移等观测工作。根据运行     

基于Autobank的水库大坝渗流安全评价分析

为进行水库大坝渗流安全评价,以Autobank软件为媒介,以勘察地质参数为基础数据,对南王水库进行渗流安全复核计算。通过复核结果与现场实际调查结果相比较,进而得出南王水库土石坝的渗流安全评价结论：南王水库坝体上游坝坡采用复合土工布防渗,下游坝脚设有反滤与排水棱体。上游坝坡采用复合土工布有效地减少了水库的渗漏量,坝脚设有反滤与排水棱体有效地降低了坝体浸润线,使浸润线到坝体下游部位渐趋平缓。大坝防渗设施较完善,坝脚反滤、排水棱体设施完善。经分析计算,各工况下,坝体渗透坡降均小于允许渗透,认为大坝渗流性态基本安全。     

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。     

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.     

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。     

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.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

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.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

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).     

The flood pulse advantage and the restoration of river-floodplain systems

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.     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。