堆石自密实混凝土重力坝施工技术要点分析

近年来,堆石自密实混凝土施工技术在混凝土重力坝施工中应用日渐广泛。本文结合工程实例,对石料筛选冲洗、仓面堆石、模板设计架设、自密实混凝土配合比选择、混凝土拌制、入仓浇筑等关键工序及堆石自密实混凝土重力坝施工技术的完善措施和常见问题进行阐述,总结分析了技术要点,供类似工程参考。     

堆石重力坝自密实混凝土砌石施工

为解决堆石重力坝空隙填充施工效率低的问题，文中提出了自密实混凝土砌石的施工方法，即先向仓面中放入大粒径块石，从而形成一个具有大孔隙的堆石仓面，再浇筑自密实混凝土实现对空隙的填充，完成水库堆石重力坝的施工。文中通过实例分析，该技术可以大大提高堆石重力坝的施工效率，缩短施工周期，减少建设成本，从而增加效益。     

基于ANSYS的堆石混凝土重力坝强度及抗滑稳定分析

坝体的强度和抗滑稳定性是重力坝在建设过程中考虑的主要因素,通过现代技术和方法分析堆石混凝土坝体的强度和应力变化等特征对坝体安全稳定预估有着重要的作用。利用ANSYS软件对甘肃省天祝藏族自治县石门河水库堆石混凝土重力坝应力和抗滑稳定性进行计算,得到以下结论:各工况下坝体混凝土层、坝体混凝土与基岩接触面均满足抗滑稳定要求,但左挡水坝段3需要进一步考虑安全加固措施;整个坝体大部分区域处于压应力状态,在坝踵与坝趾处均存在应力集中点,在坝趾处应力有最大值3.82 MPa,且应力集中范围大于坝踵处;通过对比各工况坝内关键点的正应力、剪应力和主应力大小,发现各工况下该堆石混凝土重力坝均能满足强度要求,且坝体位移在正常范围内。     

万家沟水库坝体自身防渗堆石混凝土重力坝渗流监测与分析

为了掌握万家沟水库坝体自身防渗堆石混凝土重力坝渗流情况,通过对坝基、坝体及浇筑层间的渗流监测设计和监测成果分析,并经大坝质量检测及蓄水运行检验,得出坝体自身防渗堆石混凝土重力坝坝基防渗满足要求,坝体渗流在允许范围,坝体堆石混凝土浇筑层间胶结良好,未见集中渗漏的结论,对凸显堆石混凝土优异的自身防渗性能和简化堆石混凝土重力...     

自密实堆石混凝土重力坝施工技术应用研究——以甘肃省某堆石混凝土重力坝为例

自密实堆石混凝土在大体积混凝土工程、尤其是堆石混凝土重力坝施工中应用广泛。以甘肃省某自密实堆石混凝土重力坝为施工案例,介绍了自密实堆石混凝土重力坝的施工组织与施工技术,并总结了该工程中自密实堆石混凝土坝型与传统坝型相比的优越性,以期为解决同类工程中的相似问题、在全国推广该施工技术提供经验借鉴。     

超厚层高自密实混凝土堆石坝的施工方法

针对常规堆石混凝土浇筑层厚1～1.5 m,常态混凝土和堆石混凝土分期二次浇筑,施工工期较长,不能满足2020年11月国家组织的冬季延庆杯测试赛要求.提出了超厚层高自密实混凝土同步浇筑的施工方法,通过提高自密实混凝土的性能,采用可调悬臂模板,BIM模拟演练优化施工组织,解决了超厚层浇筑和同步浇筑问题,实现了施工任务.实践...     

水库堆石坝高强自密实混凝土施工控制要点

以某水库工程为例,对其堆石混凝土重力坝高强自密实混凝土材料应用的可行性进行了概述,并对原材料选用及配合比设计进行了分析,同时对包括高强自密实混凝土制备运输、浇筑施工等在内的控制要点进行了探讨。结果表明,该水库堆石坝高强自密实混凝土施工主要利用大量堆石使普通混凝土中水泥用量大大减少,也因此避免了大体积混凝土施工可能面临的水化热问题,坝体结构安全性和稳定性明显增强,为水库大坝质量安全提供了保证。     

堆石混凝土(自密实)重力坝施工工艺研究

以龙岩坪坑水库工程为例,该工程位于龙岩市新罗区雁石镇,属2016年省政府重点建设项目,是厦门龙岩山海协作区、龙雁经济开发区和雁石集镇的重要基础设施之一,也是造福当地的重要民生工程。枢纽工程由拦河坝、引水系统及消能电站组成。大坝采用堆石混凝土重力坝,混凝土为自密实混凝土,施工过程中将满足一定粒径要求的大块石直接使用汽车运输上坝入仓,形成有空隙的堆石体,然后在堆石体表面浇筑满足特定要求的自密实混凝土(简称SCC),依靠其高流动性填充堆石体空隙,形成完整、实心密实、低水化热的大体积混凝土。文章讲述了自密实混凝土重力坝施工工艺程序,确保混凝土重力坝工程的施工质量,为其它工程建设提拱了参考。     

自密实堆石混凝土坝施工质量控制过程分析

为系统研究自密实堆石混凝土坝的施工质量控制,以贵州省遵义市余庆县余庆县小乌江水库大坝工程为例,分析研究自密实混凝土配比、堆石比、自密实混凝土性能状态及原材料的影响、自密实堆石混凝土坝技术应用,并运用科学的管理水平和先进的检验手段,对自密实堆石混凝土重力坝施工技术特点、难点开展专项技术研究和主动创新,为筑坝技术多元化发展...     

堆石混凝土及堆石混凝土大坝

本文提出一种新的大体积混凝土施工方式,即以自密实混凝土在堆石体中流动充满堆石体形成完整的混凝土,简称堆石混凝土.文中简述了堆石混凝土的优点,介绍了堆石混凝土试验,试验结果证明自密实混凝土在堆石体中有良好的流动性能,利用自密实混凝土填充堆石体,可以得到具有良好密实性和高强度的堆石混凝土.本文还结合堆石混凝土的特点,建议了几种充分发挥堆石混凝土优点的新坝型：堆石混凝土拱坝/重力坝、堆石混凝土心墙堆石坝和堆石混凝土混和坝.     

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。