李溪拦河闸下游消能工除险改造研究和实践

拦河闸下游河道河床下切、水位降低后,改变了其下游消能工运行的水文条件,会造成拦河闸下游消能工破坏,危及工程的安全运行。通过对流溪河李溪拦河闸下游消能工一、二期除险加固改造的水力模型试验成果的总结和分析,介绍了该工程下游消能工除险改造优化方案和应用情况,可供类似工程设计和运行参考。     

拦河闸下游两级消力池布置和计算研究

通常根据拦河闸泄洪水力条件、闸址地形和地质条件、两岸翼墙和堤围的安全、工程施工和投资等,拦河闸下游可选择设置一级或两级消力池。本文对拦河闸下游两级消力池的布置和水力计算方法进行了分析,提出了相应的布置和计算方法:1首先确定一级消力池水平段池底高程,计算消力池末端尾坎的合理高度和水平段池长,使一级消力池内形成稳定的水跃;2根据拦河闸闸址下游河道水位条件,在满足二级消力池出流与下游河道水流为缓流衔接的条件下,初拟二级消力池末端尾坎顶高程,计算出消力池池深和池长,使消力池出流平顺与下游河道水流衔接。本文成果得到了水力模型试验研究实例的验证,可供类似工程设计参考。     

流溪河李溪拦河闸的消能问题及改造研究

由于流溪河李溪拦河闸下游河床下切、下游水位降低,造成拦河闸下游消能工损毁,严重危及工程的安全运行。该文结合流溪河李溪拦河闸下游消能工加固改造工程的水力模型试验成果,介绍了该工程下游河道水位下降后的下游消能工改造优化方案和原型运行观察情况,可供类似工程设计和运行参考。     

西溪拦河闸下游消能工出险分析和改造研究

潮州供水枢纽工程西溪拦河闸建成运行后,其消力池下游海漫段遭受到较严重的冲刷破坏。 根据西溪拦河闸工程布置和出险的泄流水力参数,对其下游消能工出险的水力条件和原因进行计算和 初步分析,并介绍其除险改造方案试验研究成果和运行情况。研究表明,西溪拦河闸消力池下游海漫段 出险与其闸下游河道水位降低、海漫段的结构和质量等因素有关,拦河闸下游消能工除险改造试验研究 成果是合理的。     

东山拦河闸加固改造工程消能研究

由于东山拦河闸下游消力池遭受破坏,且下游河道河床下切、水位降低,需对拦河闸下游消能工进行加固改造。通过水工模型试验,在东山拦河闸现状下游消力池加固改造的基础上,为了确保消力池下游海漫段的安全运行,在海漫段上设置消力墩和消力坎等辅助消能工。研究表明:消力池下游海漫段上设置了消力墩和多级消力坎之后,海漫段的泄流消能率最高可达约50%,确保了出池水流较平顺地与下游河道水流衔接。研究成果得到了工程建设的采用,可供类似工程设计和运行参考。     

潮州供水枢纽东溪拦河闸消能工除险改造试验研究

潮州供水枢纽东溪拦河闸下游河床下切之后,河道水位明显下降,拦河闸下游消能工无法满足消能防冲的要求,危及工程的安全运行。东溪拦河闸除险改造工程对原消力池进行改造,并在其下游布置二级消力池,经水力模型试验优化后,妥善解决了拦河闸下游消能防冲的问题。     

低水头拦河闸下游一、二级消力池的布置

为了解决低水头拦河闸下游河床下切、河道水位下降造成下游消能工无法正常运行的问题,需要对拦河闸工程下游消能工进行除险改造或重建。基于广东省3座拦河闸除险改造和重建工程的水力模型试验研究成果,对低水头拦河闸下游两级消力池的布置进行研究,提出加高一级消力池尾坎顶及在下游陡坡段设置外凸型阶梯跌坎等优化措施。试验结果表明,采取上述措施可大幅度提高消力池水流消能率,简化消能工设施,节省工程投资。     

潮州供水枢纽工程西溪拦河闸消能工除险改造试验研究

由于潮州供水枢纽拦河闸下游河床下切，下游河道水位明显下降，造成拦河闸下游消能工出险。根据潮州供水枢纽西溪拦河闸下游消能工除险改造工程的水力模型试验资料，介绍拦河闸下游消能工除险改造优化方案试验研究成果及运行情况，供类似工程设计和运行参考。     

大坡山拦河闸下游消力池池深的计算和分析

低水头拦河闸下游消力池池深的主要影响因素有闸上游水位、泄流单宽流量和下游河道水位等,工程设计中,可根据泄流单宽流量、下游河道水位、下游河道地形等,先确定消力池末尾坎顶高程,然后根据不同的运行水文条件组合计算出相应的池深值,以其最大值作为池深设计值。该文通过大坡山拦河闸下游消力池尾坎顶高程、池深的计算和分析实例．验证了上述方法。     

潮州供水枢纽西溪拦河闸下游水位下降影响研究

近年来,由于潮州供水枢纽西溪拦河闸下游河床下切、下游河道水位下降,对枢纽工程运行产生了不同程度的不良影响。对此在对历年西溪拦河闸下游河道水位与流量关系变化总结和分析的基础上,对下游河道水位下降对西溪枢纽拦河闸、电站、船闸等建筑物的影响进行分析,介绍枢纽工程现行采用的改造工程措施,并对今后改造的方法进行探讨,供工程设计和运行参考。     

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。