粗粒土水平渗流试验数值模拟研究

土工模型试验中,渗流边界的确定需要详细了解岩土介质的水平渗流特性,因而水平渗流试验是研究岩土介质水平渗流特性的主要试验方法。以往在进行水平渗流试验数值模拟研究中缺乏对岩土介质入口截面速度分布均匀性的考虑,这对粗粒土的水平渗流试验的准确性分析会产生明显影响。运用ANSYS fluent模拟粗粒土水平渗流试验,改进了简化的水平渗流试验装置二维几何模型,并对比改进前后岩土介质入口截面速度分布情况。研究结果发现:简化的水平渗流试验装置二维几何模型改进后(设置一定水平管摆放高度0.4 mh0.2 m),渗流开始时岩土介质入口截面速度分布均匀度提高了20%以上,对水平渗流试验是有利的。然后根据湿润锋倾角随时间变化情况绘制出了湿润锋倾角随时间变化曲线,得到湿润锋倾角随时间呈现二次方变化,为水平渗流试验装置水平段长度设计提供了参考依据。最后针对水平渗流试验装置二维几何模型的渗流过程分析给出了水平渗流试验计时测量起点位置的确定方法。研究结果为水平渗流试验装置的设计从数值模拟的角度提供了一条新思路。     

Processing Modflow软件在地下水污染防治中的应用

ProcessingModflowforWindows是国际上较为先进的模拟地下水流动和污染物在地下水中输移的软件，它操作简便，界面良好，可用来模拟多种地下水流动和污染情况．介绍了该软件的原理、功能和使用方法，针对海河流域普遍存在的排污河，运用该软件对地下水污染的范围和程度进行了估算和预测。     

耦合高效高精度水动力模型的多组分污染物输移及衰减反应模型

为更好地模拟水污染事件中多组分污染物输移及衰减反应过程,全面耦合了基于图形处理器(GPU)加速技术的二维水动力模型与多组分污染物输移及衰减反应模型,通过改进模型源代码并在污染物输移控制方程中嵌入衰减项与反应项,建立了一个可应用于大区域复杂地形河道洪水演进全过程及多组分污染物输移和衰减反应的高性能耦合模型,同时引入GPU技术提升计算效率。将耦合模型应用于理想地形静水和两个复杂地形河道入流与溃坝算例的水质模拟,结果表明:多组分污染物输移及衰减反应过程在理想算例中的数值解与解析解基本吻合,在入流与溃坝算例中的模拟结果符合实际物理过程,模型运行速度快且计算效率高,可高效地模拟各类突发水污染事件并进行预警和评估。     

中山河口近岸海域混合区敏感点访问几率研究

以黄海中山河口近岸海域水动力、污染物输移扩散规律及污染物排放量对附近海域影响为主要研究内容。建立二维水流、水质模型,利用有限体积法离散方程并对中山河口近岸海域的水动力状况及污染物输移扩散规律进行数值模拟;选用COD为主要的污染物指标,模拟计算污染物混合区,然后确定混合区内相对不利的3个敏感点,应用统计学原理,统计混合区近岸边缘污染物访问几率。     

裂隙岩体二维渗流水力学理论模型研究

本研究主要内容包括 :裂隙岩体随机网络模拟、分形几何描述裂隙岩体参数几何特征、二维裂隙岩体等效渗透系数估算、二维裂隙岩体渗流应力耦合 非耦合模型、三维等效连续介质渗流模型、二维裂隙岩体连续介质与离散介质耦合模型、渗流模型与离散元应力模型耦合分析工程问题等。(1)利用三维裂隙网络随机模拟模型 ,针对乌江构皮滩水利枢纽工程平硐裂隙数据 ,研究其裂隙几何参数的分布情况 ,对其中一个优势裂隙组进行了模拟和检验。在模型中 ,基于蒙特卡罗方法 ,对裂隙隙宽的模拟进行了尝试。并应用分形几何的理论对其网络分维和裂隙数分维进行了研究 ,提出应用分形几何来模拟裂隙岩体中裂隙几何参数的方法。(2 )基于裂隙网络的转形 ,提出了裂隙岩块等效渗透系数的简便算法。与数值计算方法比较 ,其计算更简便迅速。 (3)推导了裂隙渗流和应力耦合的理论关系 ,建立二维裂隙岩体渗流应力耦合 非耦合非稳定流模型和三维等效连续介质渗流模型。耦合模型中应用经典耦合关系进行了计算验证 ,模型可以计算多种耦合关系。 (4)建立二维裂隙岩体连续介质和离散介质耦合非稳定流模型 ,并对其数值算法进行了研究。耦合模型使用离散介质渗透理论描述岩体主干裂隙中的水运动 ,使用连续介质渗流理论来描述岩体次要裂隙及孔     

平面二维河床变形的数值模拟

为了研究河道平面二维的河床变形问题，及由此而引起的对防洪、航运等造成的影响，本文给出出非均匀沙的平面二维全沙动床数学模型方程组，并考虑了移质不和饱和输移、非均匀沙推移质输移及床沙级配的调整。在求解水流泥沙运动方程时，采用控制体和只法及动边界技术，对水流速度场、悬移质浓度场及河床变形进行了数值模拟。该模型采用正交曲线网格来克服天然河道边界形状复杂、长度尺度相差悬殊以及由于水位波动引起计算边变化等等困     

月牙泉渗流场数学模型及治理方案研究

建立月牙泉区域非均质、非稳定流二维地下水渗流场数值模拟模型，通过模拟预测取得不同结果，并结合渗流场的水文地质条件、供水量和投资费用三者的协调统一，筛选出不同渗水条件下泉湖水位上升最佳组合作为泉湖治理方案。     

不同径流条件下钱塘江突发性水污染事故影响的预测模拟

采用二维潮流水质模型对钱塘江河口突发性水污染事故对水质的影响进行了模拟预测。分析结果表明:随着上游径流流量加大,污水团输移的速度明显加快,最大浓度也有所降低。同时随着污染物在输移过程中稀释扩散,超标总历时沿程逐渐增大,污染物最大浓度沿程逐渐降低。模拟及计算结果显示:突发污染事故后,加大上游的下泄流量,对加快污染团下移、稀释污染团从而降低污染物浓度的作用非常明显,模拟结果可为处理突发性水污染事故提供提供重要的理论依据。     

分汊型河道水流运动特性和污染物输移规律研究进展

对分汊型河道的水流运动特性和污染物输移扩散规律的相关研究进行综述,分别从分汊型河道中分汊口、交汇口、整个分汊河道的水流特性及分汊型河道中的污染物输移特性等4个方面进行总结。介绍分汊口和交汇口处的水流从其能量损失、水位变化、水流分离等一维、二维过流特征到三维流动结构和紊动特性的研究过程;从野外现场试验、室内物理模型试验和数学模型模拟等角度出发阐述了整个分汊河道的水流特性;认为污染物在分汊河道中的输运规律研究主要集中在数值模拟上,并进行了回顾和分析;提出分汊河道水流水质输移特性研究中一些有待深入探究的问题,尤其亟待加强不同排放方式、不同污染物密度和不同分汊形态下污染物输移机制的试验研究。     

基于GPU加速的污染物输移高分辨率数值模型

为了高效准确地模拟水污染事件中污染物输移过程,该文引入了一套基于GPU加速的水动力及污染物输移的GAST(GPU Accelerated Surface Water Flow and Associated Transport)高分辨率数值模型,并对水污染事件中污染物的输移进行了模拟。模型采用Godunov格式的有限体积法求解二维浅水方程和污染物输移方程,利用HLLC(Harten-Lax-van Leer-Contact)近似黎曼求解器计算单元网格界面通量,应用MUSCL限坡线性重构和龙格-库塔时间积分法实现了时空二阶精度,有效地解决了输移方程中对流项产生的数值阻尼过大和剧烈的数值振荡等问题,可准确地模拟复杂地形上干湿界面变化。同时模型引入图形处理器GPU(Graphics Processing Unit)加速计算技术。算例结果表明:模型精度高且稳定性好,能有效抑制数值阻尼和数值振荡,大幅提升了计算效率;模型可用于水污染事故的预警和评估,以期为突发水污染事件的决策提供基础数据和科学支撑。     

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。