小洋溪水库大坝除险加固设计

小洋溪水库碾压混凝土重力坝经鉴定为三类坝,需进行除险加固。在查明该水库病害现状及病害成因后,结合碾压混凝土的特点,进行了3种除险加固设计方案比选,最终采用了“主坝坝体灌浆防渗、1号副坝坝体上游面浇筑混凝土防渗面板”的设计方案,通过处理后蓄水观测证明该方案达到了除险加固的目的。     

补偿收缩混凝土面板的施工方法

碾压混凝土坝的防渗基本有两种类型：一是碾压混凝土自身防渗，二是在上游面设置专门防渗结构，龙门滩一级碾压混凝土坝防渗采用补偿收缩混凝土防渗面板，大大南昌市了坝体防渗能力，值得借鉴。     

浅谈混凝土重力坝上游面土工膜防渗技术

由于设计、施工、管理等种种原因,我国早期兴建的混凝土坝坝体渗漏问题严重,亟待加固处理.PVC复合土工膜在坝体防渗加固处理中具有施工方便、造价低、工期短、不受气候条件影响、节省工程量等优点.对混凝土坝体上游面设置土工膜防渗施工技术进行分析论述,采用PVC复合土工膜防渗处理,防渗效果良好.     

七里坡水库砌石拱坝裂缝渗漏原因分析及处理

为消除七里坡水库大坝由于砌石密实度低、未设置防渗面板等,导致高水位蓄水运行条件下坝体下游面及坝肩存在渗漏问题。经实地踏勘和钻芯取样,对大坝渗漏原因进行了全面调查分析。结合坝体应力和拱座整体稳定性复核成果,采取上游坝面增设混凝土面板与坝基坝肩增补帷幕灌浆为主的组合防渗方案进行防渗处理。大坝整治后,历经高水位和汛期大流量考验,各项指标运行正常,坝体和坝肩渗漏问题处理成功。     

土石坝排水设计分析

结合近年江西省中小型水库除险加固工程实际情况,运用工程实例,介绍土石坝坝体和坝面排水设计。文章以防渗体上游侧为坝体上游,防渗体下游侧为坝体下游。当库水向下游渗透时,穿过防渗体的坝体下游渗透水主要通过排水反滤体排向下游;当库水位下降时,未穿过防渗体的坝体上游渗透水主要通过护坡排水孔排回库区。坝面排水主要是排下游坝面及坝顶的雨水,坝面排水应与坝体排水分离排出。大坝加固实施后,下游坝脚处大面积散浸现象和多处集中渗漏点已消失,坝容坝貌得到有效改观。     

山口三级电站碾压混凝土重力坝主要施工技术

山口三级电站混凝土重力坝施工中采用全悬壁大面模板，混凝土运输以真空溜槽为主，门机运输为辅，真空溜槽布置在左岸坝肩上，真空溜槽与拌和楼之间的混凝土输送采用皮带机。本工程为全断碾压混凝土，坝体上游面采用R90200、W6二级配碾压混凝土作防渗体，防渗体以下部分则采用R90100、W4三级配碾压混凝土，由于是夏季施工，采取了遮阳处理、仓面喷雾处理等措施。     

桃林口水库(右岸)坝体工程施工

桃林口水右岸坝体工程，包括右岸非溢流坝段电站坝段泄水孔坝段计9个坝块全长147m。建基面高程74m－113m。坝顶高程146．5m。采用“金包银”坝型，RCC方法施工。坝体上游面常态混凝土防渗层厚35m．下游面常态混凝土防渗层后1．sin，中间部分为碾压混凝土。坝体主要工程量：钢筋223ot，混凝土33．2万m’。l岩面清理坝基岩面清理直接影响到混凝土的施工。保护层开挖后的岩面高低不平、风化、破碎带较多，必须采用人工清理，并采用高压风水冲洗，将岩石裂隙夹泥及碎渣冲洗干净。最后用手工将积水和泥渣清理干净，保证基岩面的岩石完好洁净．…     

观音阁水库混凝土大坝越冬面水平施工缝的开裂原因及处理措施

应用温度及温度徐变应力仿真计算和线弹性断裂力学理论，分析了观音阁大坝越冬面水平裂缝的原因是，越冬面混凝土上下层温差及内表温差的温度应力超过混凝土的抗裂强度，和越冬面附近混凝土层间抗拉强度低于本体抗拉强度所致．分析表明，随着高程的降低，其相应部位的裂缝及坝体层间稳定性越小，如不处理，其危害性越大．依据分析结果，各高程裂缝的处理原则亦不同．高程２１８．２５ｍ裂缝的上游面进行防渗处理；高程２３３．２５ｍ水平裂缝只作简单处理．具体防渗措施是采用沥青混凝土防渗面板．     

涌溪三级电站碾压混凝土重力坝结构设计

涌溪三级电站拦河坝为碾压混凝土重力坝，最大坝高81m，坝顶总长180m，本文对碾压混凝土重力坝的布置，上游坝面防渗型式，坝体横缝等进行简要介绍。     

观文水库大坝坝型方案比选

沥青混凝土心墙坝和混凝土面板堆石坝是当地材料坝中两种比较典型的坝型,心墙坝防渗体位于坝体内部,不易破坏,但是发生问题不好处理,面板坝防渗体位于坝体上游坝坡上,与外界接触,受外部环境影响较大,易破坏,但也方便修复,两种防渗体各有优缺点,文章结合观文水库现状实际情况对两种坝型进行了经济技术比较,最终采用沥青混凝土心墙坝型。     

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。     

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。     

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.