台阶式消浪护坡在土石坝加固工程中的应用研究

结合湖北漳河水库除险加固工程,采用数值模拟方法计算台阶式护坡的消浪效果,研究台阶式护坡的结构参数及大坝上游不同坝坡坡比对台阶式护坡消浪效果的影响。研究结果表明:同一入射波下,坡比相同时,平均波浪爬高随台阶相对高度的增加呈先减小后上升趋势;同一入射波下、相对台阶高度相同时,平均波浪爬高随上游坝坡坡比的增加呈先减小、后增加、再减小的趋势,总体呈减小趋势。计算分析结果表明,漳河水库鸡公尖大坝采用台阶式护坡可有效降低波浪爬高。     

一种消浪齿的构思

在风浪大的海堤工程、港工工程中，为了保护堤坝安全，消杀波浪能量，常在堤坝表面设置不同类型的消浪齿。由于风浪、潮汐是随机变量，因此消浪齿所发挥的消能效果也随机变化。各种类型消浪齿的消能效果究竟有多大，未见统计报道，但具有消能保堤作用这是共识。象山县在海堤工程中较大规模采用的消浪齿有两种类型。第一种类型是在1992年用于大目涂围垦工程4”堤A段坝头。由于该处面对大目洋，朝向东北，风浪大，所以在护坡上设置了断面250mmX250mm（图11型），高出护坡面300mm，中心距2000mm，梅花型布置的混凝土方柱消浪齿约800m’。从199…     

允许越浪堤型在城市堤防中的应用实例

由于我国堤防种类繁多,数量巨大,受经济条件限制,大多数堤防和背水侧边坡没有采取有效的工程保护措施,一旦越浪将有可能使堤顶和背水侧这坡冲蚀破坏,造成洪水漫顶和失事。但城市堤防的城区内结合城市整体规划、景观和交通等需要,采用允许越浪堤防,满足索性要求。     

浅谈灵山岛超级堤堤顶特征高程拟定

以灵山岛超级堤工程为研究对象,分析阐述项目中各特征高程取值对堤防的影响,结合工程实际,根据不同频率的设计水位、亲水性、消浪蓄浪、景观要求等因素,对超级堤堤顶特征高程进行选定,可为类似超级堤工程提供参考。     

混凝土连锁生态护坡施工技术在孝感府澴河段第3标段工程中的应用

为解决传统封闭式护坡后期维修难度大的问题,在湖北汉江堤防加固重点工程府澴河段第3标段工程中,采用预制的多孔砖搭接铺设和孔洞内种植草皮的混凝土连锁生态护坡形式,保证了护坡的稳定、强度和耐久性,降低了护坡工程对原有生态的破坏。该护坡形式与其他形式的护坡相比,施工效率高、生态环保、效益显著,在水利工程岸坡治理和城市景观坡面防护工程中具有广阔的应用前景。     

海堤加固中的钢筋混凝土栅栏板消浪机理及应用

该文以长乐国际机场海堤为例,分析钢筋混凝土栅栏板消浪机理和消浪效果,并根据工程实践,提出改进栅栏板结构建议。     

滩地刚性植物消浪作用特性研究

滩地植物有利于保障沿海地区的水安全,量化成熟期植物消浪作用是提升生态海岸韧性的基础。本文基于一般试验规律和两种波高消减模型,分析提出了新的滩地植物消浪系数计算方法,结合波高条件可计算林带消浪后波高,相关表达式由大量试验数据进行了验证,最后对比了由本文方法与规范方法计算的林带后波高。结果表明,阻尼因数及消浪系数能直观体现植物消浪作用特性,波浪传播方向上植物面积占横截面比例是影响植物消浪机理的关键无量纲参数。植物非淹没时,本文方法得到的林带后波高与规范方法接近;植物淹没时,本文方法能更准确描述植物消浪作用。相较于规范方法,本文方法考虑了植物淹没情况,直观揭示了林带密度、宽度、高度,植物平均直径,水深等参数的影响,适用于更多工况。基于植物消浪作用的模型可快速研判相关参数变化对植物消浪效果的影响,为生态海堤滩地刚性植物规划设计及数模研究提供科学和技术支撑。     

河道堤防工程护坡方案比选研究

为有效解决河道护坡治理技术在工程方案中应用性较低的问题,文章结合堤防护坡工程实际状况,对比分析了铰链式连锁砖、混凝土模袋护坡、混凝土面板护坡以及浆砌石挡土墙护墙坡4种方案的优缺点,并对各方案的优劣次序运用综合评分法进行评价。结果表明:铰接式连锁砖护坡方案在堤防工程河道治理中具有明显的优势,方案优选结果能够较好的反映河道护坡治理工程的实际状况;本研究可为不同护坡技术在河道护坡工程中的应用与比选提供一定参考依据。     

深圳市松子坑水库消涨带生态护坡研究

水库消涨带是指随水位涨落不时出没的库岸,其坡面裸露,泥沙侵蚀量大,生态环境恶劣。由于淹露交替造成生态环境极端变化,库岸消涨带植被恢复一直是全球环境领域的一项难题。采用野外定点观测方法,以植草岸坡与裸露岸坡比较研究的方式,探讨了松子坑水库消涨带生态护坡机制和生态护坡效果。     

坝面反弧对冲式消浪墩应用研究——————以宿鸭湖水库大坝除险加固工程为例

在宿鸭湖水库大坝除险加固设计中,为减小大坝坝顶高程,提出了在上游坝面设置梅花形的反弧对冲消浪墩的消浪方式,通过波浪的折射和对冲,使波浪损失大部分动能从而降低波浪爬高。水工模型试验验证表明消浪效果明显。将试验成果应用于水库除险加固工程设计中,优化了大坝上游防护与加高方案,大大降低了工程投资,可为类似工程提供实例参考。       

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。