薄壁抓斗造塑性混凝土防渗墙在肖峰水库除险加固工程中的应用

结合新建县肖峰水库除险加固工程主坝防渗墙施工,阐述薄壁抓斗造塑性混凝土防渗墙的工作原理、施工工艺、技术要求以及应注意的问题.     

薄壁防渗墙施工工艺的创新

近年,随着水利施工技术的不断发展,薄壁防渗墙工艺越来越多.从整体情况看,薄壁防渗墙的施工工艺,由于受机械设备的限制,大多数没有较好的对地层的切削、破碎能力,尤其是北方一些地区,砂卵石层较厚,颗粒直径较大(一般4～10cm),密度较高,甚至含有10～20cm的碎石(卵石),使一些薄壁防渗墙的施工机械修建防渗墙难度较大.     

冲切成槽薄壁混凝土防渗墙施工技术——以湖北省漳河水库副坝防渗治理为例

目前，还没有一种施工方法能有效地解决在非全风化并具有一定强度的岩层或砂卵石层中建造薄壁混凝土防渗墙难的问题。冲切成槽薄壁混凝土防渗墙施工技术是在原冲击成槽建造防渗墙的基础上，对冲击钻头和施工工艺加以改进，用扁钻头代替十字钻头，用正反两种循环系统进行泥浆循环的一种新防渗墙施工方法。实践证明，该工法为在风化岩层和砂卵石层中建造薄壁混凝土防渗墙提供了可能。     

黄河荆隆宫堤防超深薄壁防渗墙施工技术改进

黄河北岸荆隆宫堤段超深薄壁防渗墙，总长3188m，净深42．5m的墙段长1700m，而墙厚只有0.22m。如此薄而深的防渗墙，国内外均属罕见，施工难度很大。针对施工中出现的问题，对施工机具和施工工艺进行改进和完善。通过对该技术的总结，为超深薄壁防渗墙技术的进一步发展打下了基础。     

冲切成槽法薄壁塑性混凝土防渗墙施工

冲切成槽法薄壁混凝土防渗墙施工方法,是在原冲击成槽的基础上,对冲击钻头和施工工艺加以改进,用扁钻头代替圆钻头,防渗墙厚度由原60～80cm减为20～40cm.以小关岙水库防渗墙为例,对抛石层、卵石层及风化基岩中建造防渗墙的成墙技术进行阐述.     

塑性混凝土防渗墙在阿克达拉水库加固工程中的应用

阿克达拉水库大坝除险加固中,采用了塑性混凝土防渗墙技术。介绍了防渗墙的导墙、薄壁抓斗成槽机械造孔、泥浆系统和混凝土浇筑的施工工艺。这些技术的采用,加快了施工速度,节约了施工成本。     

塑性混凝土防渗墙缺陷分析与处理

随着施工技术的不断更新和改进,薄壁混凝土结构使用越来越普及到水利工程当中。如何在不同地质条件下,做好薄壁混凝土结构的施工至关重要,目前,大部分水库工程防渗采用薄壁塑性混凝土防渗墙,由于施工水文地质条件、施工工艺、施工气候环境以及人为因素的影响,施工过程中难免出现质量缺陷,针对防渗墙缺陷产生的原因,做好缺陷的分析与处理是确保工程建设质量的根本。     

薄壁塑性混凝土防渗墙技术在水库除险加固工程中的应用

薄壁塑性混凝土防渗墙技术适用于坚硬的生壤与砂砾石中成槽,成槽深度可达60m,不仅可以降低工程造价,而且可以提高施工进度。介绍了该技术在大王邑水库坝体和地基除险加固中的应用,分析了水库存在渗漏问题的原田,完整地阐述了薄壁塑性混凝土防渗墙的施工工艺及注意事项,水库除险加固后防渗效果明显,该技术很有推广价值。     

塑性混凝土薄壁防渗墙施工技术在沙湾水电站的应用

塑性混凝土薄壁防渗墙在深层砂砾石覆盖层河床的使用,在水电工程中是不多见的,特别是在大渡河上砂砾石自然颗粒级配较差、大卵石含量较多、透水性极强的地质条件下,采用"打抓结合成槽法"、"气举反循环排渣清孔法"等先进技术和施工工艺,克服造孔成槽、漏浆塌孔严重等诸多困难,按照设计要求,利用塑性混凝土成功地形成了素混凝土地下连续防渗墙,成墙质量、防渗漏效果都达到了设计要求,并通过渠内开挖到设计渠底,没有出现明显渗漏的事实,验证了塑性混凝土薄壁防渗墙的成功运用。     

黄冈赤东段长江大堤超深薄壁防渗墙施工技术

黄冈赤东段混凝土薄壁防渗墙,墙厚0.3m,墙深35m,最大深度达37.5m,如此薄而深的防渗墙,国内外均属罕见,再加上本段地层粉细砂层厚度达10m,施工难度很大。针对施工中出现的问题,对施工机具和施工工艺进行改进和完善。通过对该技术的总结,为在深厚粉细砂层中施工积累了一定经验。     

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。