水布垭面板坝挤压边墙技术有限元计算分析

挤压边墙技术是混凝土面板堆石坝中垫层料施工和保护的新技术。本文结合水布垭工程,应用有限元分析技术,对挤压边墙有关的一些问题进行了探讨。分析认为,当混凝土面板与挤压边墙取小约束、挤压边墙与垫层取大约束、挤压边墙取低强度、低弹模、泊松比为0.25～0.30,内摩擦角不少于40°时,水布垭面板坝设置挤压边墙不会对面板、接缝应力变形带来大的影响,面板和挤压边墙的脱空值较小。     

挤压边墙施工技术在斜卡水电站深厚覆盖层面板堆石坝的适应性初探

挤压边墙技术作为混凝土面板堆石坝垫层料的施工新技术,与传统的超填削坡、斜坡碾压施工工艺相比具有特定的优势。但由于混凝土挤压边墙在施工结束后将成为坝体永久工程的一部分,势必会给混凝土面板带来一定的影响。斜卡水电站面板堆石坝地处严寒地带,坝高110m,覆盖层平均深度65m。通过二维非线性有限元分析,对挤压边墙与面板间接触材料参数、挤压边墙与垫层间接触参数以及挤压边墙自身材料力学参数等三个设计要素以及对深覆盖层面板坝的适应性进行了敏感性分析,初步探讨了面板——挤压边墙间约束强度与面板的变形受力条件、地基覆盖层深度与面板——垫层料之间的脱空等相互关系,为施工决策提供依据。     

混凝土面板堆石坝固坡新技术探讨

挤压式混凝土边墙固坡技术源于巴西的Ita坝,是面板坝垫层料施工技术的重要创新。我国现已有20余座面板坝采用。其混凝土配合比要求低强度、低弹模、半透水性。采用专用挤压机沿坝体上游边线把零坍落度混凝土挤压成墙固坡,简化了垫层区的施工工序,加快了施工进度,提高了压实质量。挤压混凝土边墙固坡综合技术优势显著,经济上与传统的超填、削坡、斜坡碾压施工方法相当,其应用产生的诸如面板约束裂缝等问题,可通过采取相应的技术措施得到解决。     

挤压边墙施工技术在水布垭工程中的应用

混凝土挤压边墙应用在面板堆石坝填筑体上游坡面,材料为干贫性混凝土,通过专门设备挤压成设定形状。由于挤压边墙技术能够简化施工程序,加快面板堆石坝坝体填筑施工进度,故推广应用较快。结合挤压边墙在水布垭面板堆石坝中的应用实例,介绍了挤压边墙施工技术、挤压机工作原理、施工中出现的缺陷和处理方法,分析了挤压边墙混凝土和垫层料之间的区别、墙体变形规律,说明了挤压边墙技术是成熟的,为该技术的推广应用积累了一定经验。     

混凝土面板堆石坝垫层料移动边墙施工新技术

在对大坝垫层料边坡挤压滑模试验和垫层料移动边墙挤压试验方案研究比较后．决定在察汗乌苏面板堆石坝中采用垫层料移动边墙挤压技术。现场质量检测表明,采用该技术可满足设计要求;且与传统方法相比减化了施工工序,加大了施工灵活性,加快了施工进度,降低了工程造价。移动边墙挤压技术的应用对于混凝土面板堆石坝垫层料施工技术的发展起到了推动作用。     

混凝土面板堆石坝坡面固坡技术初探

针对混凝土面板堆石坝垫层料上游保护的常规施工费工、费时、费料等不足,借鉴巴西ITA等高坝的工程经验,在垫层坡面采用挤压混凝土边墙(挡墙)技术,通过对河南省盘石头水库工程混凝土面板堆石坝进行碾压试验,利用特制的移动式模板,对挤压混凝土边墙技术进行验证,结果表明:该挤压混凝土边墙技术是经济有效和切实可行的.     

地质雷达检测法在梨园水电站挤压边墙脱空检测中的应用

为防止因挤压边墙与垫层料之间的脱空影响混凝土面板受力条件,在面板混凝土施工前需对挤压边墙与垫层料之间的脱空情况进行检测。梨园水电站采用地质雷达检测法对挤压边墙脱空情况进行检查,并通过打孔试验验证了其可靠性。地质雷达在面板堆坝挤压边墙的脱空检测中效果明显,在满足其测试条件下,充分体现了其无损、快速、可视、数据量大等优点,并且脱空深度可精确至2~3 cm。     

面板堆石坝挤压式混凝土边墙技术在水布垭面板坝中的应用

介绍水布垭面板堆石坝上游垫层坡面混凝土挤压边墙的试验研究与应用。该项技术在我国青海公伯峡面板坝、湖北恩施芭蕉河面板坝率先运用，它替代了传统工艺中垫层料的超填、人工和机械削坡修整、斜坡碾压、坡面防护等。水布垭工程在大坝一、二期填筑施工中，应用挤压式边墙施工技术，在简化施工工序、提高安全生产等方面的优势在大坝上游垫层区的施工中非常明显。     

挤压边墙技术在老虎潭水库的应用

1混凝土挤压式边墙新技术混凝土挤压式边墙施工技术是混凝土面板堆石坝上游坡面施工的新方法,国外工程已有成功的经验,巴西的埃塔坝工程首次采用了这种新型施工技术,因其替代传统工艺中垫层料的超填、削坡、修整、碾压、坡面防护等工序,加快了进度,施工质量得到了保证和提高。国内这种新技术在公伯峡混凝土面板堆石坝中首次成功应用,挤压式混凝土边墙与传统工艺相比存在许多优点,简化了施工工序,加快了施工进度,使垫层料的施工质量更有保证,对安全生产、文明施工具有十分重要的意义。混凝土面板堆石坝上游坡面的传统施工方法是在垫层料填筑…     

潘口水电站面板堆石坝挤压边墙施工技术

混凝土面板坝上游坡面施工是控制坝体填筑进度和影响坝体质量的关键环节.混凝土挤压边墙施工技术是在垫层料的上游侧采用机械设备挤压而形成一道混凝土边墙,避免了传统工艺垫层料超填、斜坡碾压、削坡等繁琐工序,是面板堆石坝上游坡面施工的新方法.堵河潘口水电站上游坡面施工采用该技术,简化了垫层料的施工工序,加快了进度,将斜坡碾压改为...     

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。     

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.     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。