某水电站坝前堆积体成因机制分析及稳定性评价

拟建某水电站坝前堆积体稳定与否直接影响电站的枢纽布置方案选择及后期施工和运营。然而,不同时期、不同成因机制的堆积体稳定性相差甚远,因此,从堆积体成因机制分析着手,对堆积体进行稳定性评价意义重大。通过定性分析和稳定性计算得知:该堆积体整体稳定性较好,对枢纽布置方案选择及后期施工和运营影响较小。     

厚度巨大堆积体稳定性研究

针对枕头坝一级水电站库区堆积体厚度巨大、距离坝址近、面积广、总方量大等实际情况,通过对地形地貌、岩土性质、地质构造、水文地质条件、堆积体变形破坏特征、堆积体成因机制等进行分析,采取定性、定量稳定性计算和边坡监测,得出了堆积体稳定的结论,节省了大规模治理费用,为电站长期安全运行提供了保障。     

白水泉水电站左坝肩崩塌堆积体稳定性分析及处理

白水泉水电站左坝肩分布着范围大、结构松散、厚度变化大的崩塌堆积体,使电站的安全运行存在严重的隐患,其稳定性是该工程坝址区主要的工程地质问题之一。笔者通过在前期勘察中利用多种勘探手段和计算方法对该崩塌堆积体进行稳定性分析,提出了相应的处理措施,并在工程的实施过程中得到了部分应用,最终使该崩塌堆积体取得了良好的处理效果。     

西藏某水电站近坝库岸滑坡稳定性分析与评价

近坝库岸堆积体边坡的稳定性,对电站的安全运行及其上居民安全影响至关重要。以西藏某水电站近坝库岸滑坡堆积体为例,针对该滑坡堆积体蠕变、蠕滑进行了专门的勘察与监测,通过勘探、物探、试验及变形监测等资料,采用极限平衡法及有限元强度折减法进行稳定性分析,查明了堆积体的稳定边界条件,验证了滑坡堆积体的变形破坏形式与实际相吻合。结果表明:堆积体整体处于临界失稳状态,预测其破坏形式将以蠕滑塌岸的方式调整至稳定,不会产生大范围的高速滑坡,同时也不会堵塞水库。     

阿海水电站左岸坝前堆积体边坡稳定性综合研究

阿海水电站左岸坝前堆积体的稳定性对水电站工程的顺利进展相当重要.采用快速拉格朗日程序(FLAC-3D),对其进行了三维稳定性计算.从位移变形情况、剪切塑性区分布情况及地下水等影响因素分析,得出结论:水库正常蓄水后,堆积体水面以下的陡坎部位首先破坏,随后牵引堆积体中间部位沿底层滑移面滑动,发生局部的牵引式逐级滑动破坏模式.通过极限平衡法计算得到的堆积体的在不同工况下的稳定性安全系数,除自然条件下,远小于电站运营期边坡安全指标,堆积体均处于临界或破坏状态.自动搜索的滑移面与三维模拟计算情况相互验证,滑移面都是从堆积体的中部开始,通过底层的粉细砂层滑出破坏.堆积体的综合分析可为其破坏的防治与处理提供有力依据.     

乌弄龙水电站坝前堆积体稳定性分析

乌弄龙水电站坝前堆积体成因主要为崩塌堆积,岩土物理力学试验成果及现场天然休止角测量成果对选取岩（土）体的力学参数具有较好的参考价值。采用刚体极限平衡法和有限元强度折减法对堆积体的稳定性进行计算分析,评价认为在天然状态下,坝前堆积体稳定性好;水库蓄水后,堆积体前部（约70 m高差）处于库水位以下,堆积体基本稳定;在蓄水和地震工况下其稳定性降低,存在失稳的可能性,可能产生的破坏形式为前缘调整性坍岸再造。针对澜沧江上游段类似的大型崩塌堆积体,分析总结了一套松散堆积体稳定性分析评价方法,对类似工程地质问题（特别是澜沧江上游江段水电工程）研究有一定的借鉴意义。     

小湾水电站左岸坝前堆积体在自然状态下稳定性的平面离散元与有限元分析

使用平面离散元法(UDEC)和有限元法对小湾水电站左岸坝前堆积体在自然状态下的稳定性初步进行了二维数值计算与分析，得到该堆积体应力和变形状态的定量结果，对堆积体的稳定性有了相应的认识。     

某水利枢纽坝前堆积体强度参数取值及稳定性评价研究

某水利枢纽坝前左岸存在一堆积体,该堆积体的失稳将给工程带来不利影响。在分析该堆积体工程地质特征基础上,通过大剪试验、测量自然坡角和统计平洞弃渣坡角获得了堆积体及滑带的强度参数,并采用毕肖普条分法(圆弧搜索滑动面)、传递系数法(非圆弧整体滑动)和摩根斯坦法对坝前堆积体进行了稳定性计算分析。结果表明:堆积体在天然状态下处于稳定状态,在水库蓄水及地震影响下将发生失稳。     

小湾水电站左岸坝前堆积体在自然状态下稳定性的平面离散元与有 …

使用平面离散元法（ＵＤＥＣ）和有限元法对小湾水电站左岸坝前堆积体在自然状态下的稳定性初步进行了二维数值计算与分析，得到该堆积体应力和变形状态的定量结果，对堆积体的稳定性有了相应的认识。     

西坡滑坡体稳定分析

滑坡体稳定性是水利水电工程要研究的主要工程地质问题之一。介绍了龙潭嘴电站水库内西坡大型古崩塌堆积体的水文地质资料,应用反演分析、类比法、稳定计算等方法,论证了古崩塌堆积体的稳定性,分析与计算结果为滑坡体的稳定提供了依据。     

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.