砂岩骨料在斯登沃代(Stung Atay)水电站大坝混凝土中的应用

斯登沃代水电站开展的砂岩骨料大坝混凝土应用研究成果表明:工程区域料场砂岩骨料具有吸水率大、微粒含量较多等特点,用其配制的混凝土存在用水量大、胶凝材料多和混凝土干缩、湿胀变形较大等缺陷。因此,在工程使用硅酸盐水泥进行混凝土配合比设计的同时,建议采用减水率更高的缓凝高效减水剂;同时,应加大粉煤灰掺量,以达到抑制骨料碱硅酸反应,减少混凝土胶凝材料用量,降低混凝土水化热温升,减少混凝土的收缩变形,提高混凝土的抗裂性能和耐久性能。     

粉煤灰、微膨胀剂在贵港船闸混凝土中的应用

针对船闸大体积混凝土温控问题，除采用常规的温控措施外，在实践中从混凝土材料着手，即掺加粉煤灰和外加剂混缔造主掺加微膨胀剂和外加剂混凝土，均能经济有效地解决大体积混凝土温控和防裂问题。     

废弃玻璃粉在混凝土中的应用机理及ASR风险

废弃材料广泛应用于土木工程领域,废弃玻璃粉用作混凝土辅助胶凝材料符合我国建材的可持续发展要求。在大量文献调研的基础上,分析废弃玻璃在混凝土中应用的可行性。结果表明,玻璃在复合胶凝材料水化硬化过程中不仅具有一些特殊的作用机理,还存在ASR风险。由于含有大量的无定性二氧化硅,玻璃用作骨料时容易引发碱-骨料反应,但磨细成粉料可用作活性辅助胶凝材料。因此,本文提出将废弃玻璃粉磨成粉体材料用作混凝土辅助胶凝材料,并探讨废弃玻璃粉在复合胶凝材料水化硬化过程中的作用机理及ASR风险。将废弃玻璃磨细成粉料,既可以解决玻璃骨料的碱-骨料反应问题,还能发挥其火山灰作用,改善混凝土的性能。     

高效减水剂X404在三峡工程中的应用

碱峡工程泄洪孔，侧墙采用R28400D250S10（强度等级C40）标号的抗冲耐磨混凝土，由于这种混凝土的水泥用量大，水化热温升高，为解决夏季混凝土浇筑的温控防裂，施工中采用了X404高效减水剂大满足设计与施工要求的情况下，能降低胶凝材料47kg/m^3，降低水化热温升6℃，有效地解决了温控问题，大大提高抗冲耐磨混凝土抗冻耐久性能。     

缓凝高效减水剂X404在三峡工程中的应用

三峡工程泄洪孔侧墙采用R28400D250S10（强度等级C40）抗冲耐磨混凝土，由于这种混凝土水泥用量大，水化热温升高，为解决夏季混凝土浇筑的温控防裂问题，施工中采用了X404高效减水剂。该减水剂可满足设计与施工要求，并能降低胶凝材料用量47kg/m^3，降低水化热温升6℃，有效地解决了温控问题，大大提高了抗冲耐磨混凝土的抗冻耐久性能。     

含粗骨料的超高性能混凝土受弯试验研究

超高性能混凝土（以下简称ＵＨＰＣ）胶凝材料用量大，生产成本高，因此限制了其工程应用。通过在ＵＨＰＣ中适当掺入粗骨料，可有效减少胶凝材料用量，降低成本。设计制作了７组含粗骨料的ＵＨ- ＰＣ梁试件，通过四点弯曲试验，研究粗骨料质量掺量（０％、１５％、３０％、４０％）和钢纤维体积掺量（０％、１％、２％、３％）对ＵＨＰＣ弯曲性能的影响。结果表明:当未掺入钢纤维时，随粗骨料质量掺量增加，ＵＨＰＣ抗弯强度先降低后提高，且试件均发生脆性破坏；当掺入钢纤维时，ＵＨＰＣ的初裂强度和极限抗弯强度随钢纤维体积掺量的增加而提高，试件由脆性破坏变为延性破坏；当钢纤维体积掺量为２％时，含粗骨料ＵＨＰＣ弯曲韧性最高。     

三级配泵送混凝土在百色水穗枢纽工程中的应用

文章通过三级配泵送混凝土在百色水利枢纽工程中的成功应用实例，拓宽了泵送混凝土的发展前景，节省了胶凝材料用量，有利于简化大体积混凝土的温控措施，并有效地降低了工程造价。     

埋石混凝土在水利水电工程实践中的应用

埋石混凝土在水利水电工程大体积混凝土重力坝、混凝土拱坝、护坡、挡土墙、堤防等工程中广泛应用。工程实践研究,埋石混凝土节省混凝土水泥、混凝土骨料、粉煤灰、胶凝材料、外加剂的用量;减少混凝土浇筑温度裂缝、简化温控防裂措施;分坝段、分仓、分层浇筑,提高混凝土施工质量、节约资源、保护环境、缩短建设工期、降低工程投资。结果表明：埋石混凝土实施效益显著,可在水利水电工程中推广应用,从而推动埋石混凝土应用技术的高质量发展和创新提升。     

磷渣粉替代粉煤灰在水工混凝土中的应用研究

对磷渣粉的化学成分、微观结构和形貌特征,以及磷渣粉和粉煤灰作为掺和料对胶凝材料及水工混凝土性能影响进行了试验研究。结果表明：掺磷渣粉的混凝土绝热温升显著降低,混凝土拌和物有一定程度的缓凝,有利于大体积混凝土的施工、温控和防裂;磷渣粉可提高混凝土后期强度增长率和极限拉伸值,对混凝土的抗渗、抗冻性能无不利影响;磷渣粉可部分或全部替代粉煤灰在水工混凝土中大量应用。     

温升抑制剂对薄壁大体积混凝土防裂效果分析

混凝土水化热抑制剂作为新型的混凝土外加剂，具有减缓混凝土初期水化反应放热速率的作用。但由于缺乏明确的可行性分析，其在工程中的应用受到限制。通过拟合试验数据，获得不同水化热抑制剂掺量的混凝土热力学参数，并以水闸为例，采用数值模拟方式，研究水化热抑制剂对大体积混凝土温度场和应力场的影响。结果表明，水化热抑制剂的掺量达到胶凝材料含量的0.6%时，具有明显的降低温度和应力峰值作用，温控效果明显；而掺量较低，则无明显温控效果。水化热抑制剂降低温度和应力峰值的效果与结构厚度成反比，其对大体积薄壁结构的温控效果更为显著。作为一种温控手段，工程中可与其他温控措施相结合，提出更为合理且经济的温控方案。     

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.