大型水电工程水泥灌浆质量管理研究

水泥灌浆在水电工程中广泛使用,其施工质量关系到工程安全和投资风险,基于当前灌浆施工作假现象频繁发生,作为项目管理的主导者,甲方应积极推进和提升质量管理。从分标设计、计价方式、记录仪管理、水泥核销、第三方质量检查和制度建设等方面进行分析,提出了改进意见,为其他项目的水泥灌浆质量管理提供借鉴。     

水电工程施工承包合同计价方式选择

水电工程投资大、工期长,合理选择施工承包合同计价方式无论对于发包人控制工程投资,还是对于承包人降低成本,控制风险,都具有十分重要的意义。实践中,水电工程施工合同一般采用以固定单价承包为主,固定总价承包为辅的计价方式。以向家坝水电站工程施工合同为例,重点讨论了固定总价承包计价方式在水电工程施工过程中出现的问题和解决方法。     

龙滩水电站坝基固结灌浆施工过程中的质量控制

在龙滩水电站固结灌浆施工方案上,尽量选择有利于质量控制的有盖重灌浆方法;在灌浆分段方式、灌浆压力控制、浆液浓度变换以及灌浆工序上,均采取一系列的措施进行了质量控制;在出现特殊情况下也有相应的质量控制对策。控制措施获得较好效果,可供其他类似工程参考。     

水电工程水泥灌浆智能控制方法与系统

水泥灌浆是水电工程基础加固和防渗的重要措施。面向水泥灌浆核心工艺过程控制,基于"全面感知、真实分析、实时控制"的闭环智能控制理论,本文提出了三区五阶段P-Q-C-t联动智能灌浆控制方法,通过灌浆压力P、注入率Q、浆液密度C、岩体抬动值ΔH、浆液温度T及灌浆历时t的实时联动智能控制,实现了正常灌浆和特殊情况灌浆一体化智能识别和控制。研发了智能灌浆单元机iGC和智能灌浆管理云平台iGM组成的智能灌浆系统,实现了水泥灌浆一键式闭环智能控制。在乌东德、白鹤滩等水电站的固结灌浆和高压帷幕灌浆工程中应用显示,该方法与系统提高了水泥灌浆工程的施工质量,具有较高的推广和应用价值。     

基于统计分析的水电工程项目施工成本控制

结合水电工程项目施工成本控制的现有特点,剖析了传统水电工程项目施工成本控制的的依据和方法及其控制方式利弊的对比,建立了基于统计分析的新施工成本控制体系。并在此基础上确定施工项目成本资料的管理措施以及施工成本控制定量制订和考核的依据,力求达到成本控制和分析方法的准确性,促进项目成本控制的管理水平提高。     

控制水利工程灌浆施工质量的有效措施

水利工程灌浆施工项目是确保工程施工效果的关键环节,是提高水利工程质量的重要因素,所以当前灌浆施工技术已被广泛运用至水利工程的各个环节。为了有效控制水利工程灌浆施工质量,文章对现阶段的灌浆施工技术进行了深入地分析,阐述了导致水利工程灌浆施工项目出现质量问题的原因,并就此提出了有效加强水利工程灌浆施工质量的措施。     

水布垭水利枢纽放空洞固结灌浆施工

简要介绍了水布垭枢纽固结灌浆施工方法和施工程序,对灌浆成果和质量进行了分析。根据工程实践经验,对隧洞固结并联灌浆孔的对称形式和压力控制以及封孔方式提出了见解。     

水布垭水利枢纽放空洞固结灌浆施工

简要介绍了水布垭枢纽固结灌浆施工方法和施工程序，对灌浆成果和质量进行了分析。根据工程实践经验，对隧洞固结并联灌浆孔的对称形式和压力控制以及封孔方式提出了见解。     

苗尾水电站帷幕灌浆试验及灌浆效果研究

苗尾水电工程地质条件复杂,为保证苗尾水电工程基础帷幕灌浆的防渗效果,需要研究并采用适合该工程的帷幕灌浆工法。通过选取地质条件较复杂的部位采用试验工法进行帷幕灌浆生产性试验并对灌浆试验效果进行检查,总结出适合该工程的帷幕灌浆生产工法。通过生产工法的使用,灌浆质量检查合格率明显提高,满足了设计要求,帷幕灌浆施工质量得到保证。     

水电工程固结灌浆计价方式

水电工程固结灌浆计价方式目前存在多种方法,介绍了国内常见的固结灌浆计价方法,并分析了其中的优缺点,提出了建议,即在工程量清单中直接按每米水泥干灰量设置多个区段,投标人按工程量清单报价,该方法简单、方便、易操作,且投标人自行测算每个区段的单价水平,每个孔固结灌浆结束后,直接结算到对应的合同清单项目中。投标人的报价高低风险由其自行承担。     

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.