高坝洲水电站重力坝深层抗滑稳定研究

采用三信有限元法计算了高坝洲水电站表孔溢流坝段的支抗滑稳定安全系数，得出最危险坝段，并用一次二阶矩法计算最危险坝段的可靠度，同时研究了各随机变量对可靠指标的影响。     

丹江口大坝31号坝段变形监控指标的探讨

对丹江口大坝３１号坝段具有代表性的测点的位移实测数据进行分析，并结合有限元计算，探讨了该坝段的变形监控指标。将大坝变形监控指标分为一般警戒值，特别警戒值和危险值三级，并分别用置信区间法，典型监测量的分量挑选法和平面弹塑性有限元计算为丹江大坝３１号坝段拟定了它们的具体数值。这些变形监控指标可供该坝段实际运行观测时参考。     

丹江口大坝31号坝段变形监控标的探讨

对丹江口大坝３１号坝段具有代表性的测点的位移实测数据进行分析，并结合有限元计算，探讨了该坝段的变形监控指标。将大坝变形监控指标分为一般警戒值、特别警戒值和危险值三级，并分别用置信区间法、典型监测量的分量挑选法和平面弹塑性有限元计算为丹江口大坝３１号坝段拟定了它们的具体数值。这些变形监控指标可供该坝段实际运行观测时参考。     

复杂坝基浆砌石重力坝稳定分析

以宝泉电站下水库大坝特殊坝段为例,采用刚体极限平衡法时复杂坝基浆砌石重力坝的抗滑稳定性进行了分析,由其二维有限元计算结果可知,校核水位时为最危险工况,坝体与坝基接触面上的最大垂向正应力和最大切向剪应力均出现在坝趾处.介绍了特殊坝段的极限抗倾稳定验算方法,指出在施工过程中确保坝体与基础充分结合是特殊坝段抗滑稳定的前提条件.     

观音阁水库大坝岸坡坝段的设计

观音阁水库大坝左岸句1～5岸被坝段应落于倾角为48～63°的陡坡上．在左岸岸坡坝段的设计中，吸取了国外经验，特左岸几个坝段全部王于开挖成陡坡的基岩面上．计算中采用高、陡岸被坝段平面计算方法──极限强反法的基本原理，并将计算结果与三维地质力学模型试验和三维有限元计算结果进行验证对比．结果表明，极限强度法计算结果正确，计算程序可靠，计算设计合理，可供陡岸被坝段设计参考．     

丰满水库新坝施工对旧坝抗滑稳定的影响

采用有限单元法实施丰满大坝新坝坝基开挖及坝体浇筑施工,对旧坝抗滑稳定性影响进行了数值仿真计算。选取了新坝施工期间对旧坝最不利的坝段,并将此坝段作为典型坝段,分析其遭遇不同频率洪水时的抗滑稳定性,得出新坝坝基开挖及坝体浇筑施工,对旧坝抗滑稳定性影响不大的结论。     

万家寨水利枢纽岸坡坝段稳定与应力分析

万家寨水利枢纽拦河坝轴线处河道断面呈偏宽“Ｕ”字形，坝型为直线半整体式重力坝。由于两岸边坡陡峻，岸高在１００ｍ以上，存在高边坡坝段的稳定及应力问题。在设计中先后进行了坝体三维模型试验，采用刚体极限平衡法，拱梁分载法，有限元分析法进行分析计算，得出的结论是：边坡坝段之间与河床坝段之间采用半整体式为连接为宜；边坡坝段之间的并缝高分别为９４８ｍ，９４０ｍ，岸坡坝段与河床坝段之间在９１５ｍ高程并缝；燕缝水     

重力坝深层抗滑稳定的非线性及线性计算分析比较

运用ANSYS计算程序，针对万家寨水利枢纽工程坝体沿坝基深层软弱夹层抗滑稳定问题，以6#坝段为典型坝段，应用Drucker-Prager(DP)屈服准则进行非线性有限元计算。与线性计算结果比较，应力场及安全系数相差很小。     

某水电站溢洪道导墙坝段有限元应力分析

以某水电站溢洪道导墙坝段为研究对象,应用大型通用有限元计算软件对溢洪道导墙坝段进行了应力计算,得到溢洪道导墙坝段整体、主要部位的第一主应力、第三主应力,计算结果基本符合实际情况,这为在施工期的导墙安全结构设计提供了可靠的参考数据。     

万家寨水利枢纽重力坝可靠度分析研究

按国家标准［１］计算万家寨水利枢纽３个典型坝段坝基面的应力、稳定及其可靠度，按非线性随机有限元方法，研究各坝段在大坝与地基联合作用下的整体稳定可靠度。     

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.