基于水力层析法的渗漏通道反演研究

渗漏通道反演研究对探测堤坝渗漏起着非常重要的作用。通过数值抽水试验,运用水力层析法对含水层渗漏通道进行了反演研究。建立了一个二维垂直饱和渗漏含水层,含水层大小为18 m×18 m,渗漏含水层布设3口斜井。通过非稳定流抽水试验,在监测点监测不同时刻的水头响应数据,运用连续线性估计方法(SSLE)对含水层储水系数进行反演,结果表明:通过非稳定流抽水试验刻画渗漏含水层储水系数的详细分布,能够有效识别渗漏通道分布情况;斜井多的情况下,可以揭露更多的含水层信息,获得更多的水头响应数据,最终的识别效果好于斜井少的情况;地质资料齐全的情况下,非稳定流水力层析法能够准确探明渗漏通道的位置。     

一种基于MATLAB的渗透系数确定方法

地下水资源评价与地下水可开采量计算需要对地下含水层参数进行分析确定。结合托克托县地区抽水试验,运用MATLAB软件优化传统的Jacob直线图解法和标准曲线配线法,在单孔非稳定流抽水试验中确定承压含水层导水系数T和渗透系数K,计算结果符合当地水文地质条件,且比传统方法精确可靠。     

抽水试验反演水文地质参数的多线全程加权法

抽水试验是反演场地水文地质参数的重要依据,针对多观测井全程抽水试验的水文地质参数反演问题,提出了描述观测井数据可靠性的权重概念,构建了利用多个观测井的抽水阶段与水位恢复阶段实测数据、反映观测井数据可靠性的多线全程加权法,并利用遗传算法杂交策略改进的杂交粒子群算法,实现了多线全程加权目标函数的最优求解。在此基础上,以南京江北新区现场抽水试验为背景,基于场地水文地质条件概化的越流承压含水层计算模型,反演了场地含水层的导水系数、贮水系数和越流因数,分析了多观测井抽水试验反演水文地质参数问题引入观测井权重的必要性,验证了多线全程加权法反演水文地质参数的合理性,探讨了杂交粒子群算法求解多线全程加权目标函数的有效性。研究表明,多线全程加权法与杂交粒子群算法结合,为利用多观测井现场抽水试验合理反演水文地质参数提供了一条新的途径。     

基于井水位潮汐响应探讨含水层的水力特征及其变化

为了科学地认识应力荷载对地下水渗流运动规律的影响,揭示井孔-含水层系统与地震活动的响应关系,以华蓥山断裂带附近的大足井和北碚井为例,基于潮汐响应推求观测段含水层水力特征参数,探讨汶川地震对含水层水力特征及地下水流运动状态的影响,并对其变化机制进行解释。结果表明：大足井附近含水层中地下水运动以径向流为主,利用潮汐径向流模型计算出含水层水平渗透系数与以往抽水试验的结果基本一致;北碚井孔-含水层系统中地下水垂向流和径向流并存,引入越流含水层系统模型得到越流系数范围为1.5×10-8~2.5×10-8 s-1;汶川地震后,北碚和大足井水位均发生了阶降变化且含水层中地下水垂向流运动增强,分析认为原因是该区域侏罗系砂岩含水层在较大范围内存在着统一的水力联系,且局部裂隙发育,倾角较大,地震导致含水层发生膨胀变形和裂隙疏通,在重力作用下地下水顺层或沿裂隙通道流动。研究结果有助于提高对含水层受力变形与渗流相互作用的认识,进一步深化井孔-含水层系统对地震活动响应机制的研究     

双孔干扰非稳定流抽水试验确定承压含水层水文地质参数

在大型地下水资源论证开发过程中,常通过群孔抽水试验以确定目标含水层相应水文地质参数,从而进一步探求地下水储量。而该方法对于一些小型地下水资源的开发而言其钻孔成本较高。为控制项目,采用双孔干扰抽水试验以获得目标含水层渗透系数。通过抽水试验数据以及水位恢复数据计算得到目标承压含水层导水系数为20.5~41.4 m~2/d。该结果表明双井干扰抽水试验既能有效获取目标含水层水文地质参数,也能大幅降低项目成本,较适用于小型地下水资源的论证及开发。     

阶梯状抽水试验水文地质参数确定

针对传统阶梯状抽水试验参数计算过程中,通常只选择抽水阶段的部分试验数据等问题,应用Theis公式及叠加原理,利用抽水试验所有降深数据(抽水和水位恢复阶段全部资料)求解水文地质参数,利用承压含水层抽水试验数据计算得出导水系数、储水系数,利用潜水含水层抽水试验数据计算得出渗透系数和给水度,此外在低效率抽水井中利用抽水试验数据计算得出井损系数和井流量指数。计算过程中,利用Excel计算并绘制计算水位降深和观测水位降深的拟合曲线,计算过程简单快捷。整个抽水试验过程中,不必再分别提出抽水、水位恢复期的计算公式,可以避免人为选择单个水位降深数据对参数求解带来的影响。     

锅称子抽水试验及地下水可采资源的评价

抽水试验是目前各种水文地质勘察中经常用来确定含水层水文地质参数的一种主要手段,在详细勘察阶段,更是其工作的主要内容。通过抽水试验来确定含水层的钻孔涌水量及其与水位降深之间的关系；含水层的水文地质参数；影响半径的大小、降落漏斗的形状及其扩展情况；含水层与含水层之间及其含水层与地表水之间的水力联系等。并通过多孔抽水试验及历年降雨和地下水动态观测与分析,初步对我地区地下水可开采资源做出评价,指导工农韭生产中的地下水开发利用,制定合理的灌溉制度,扩大灌溉面积。     

基于抽水试验的渗流问题摄动随机反演方法

针对地下水渗流随机参数反演问题，在正演随机模拟方法的基础上，结合非平稳随机过程变量的一阶Taylor展开式和随机参数的摄动方程，讨论了多随机参数反演问题，提出了基于抽水试验的渗流问题摄动随机反演方法，给出一阶均值反演准则，得到多随机变量的均值和方差的近似表示方法。该方法在计算均值时采用改进的遗传算法，在计算方差时采用分组统计的方法。最后给出了一个基于Thies模型反演导水系数和贮水系数的例子，计算结果表明，该方法可以较好的求取参数的均值，近似地求取参数方差。     

基于VBA和群井叠加原理的水文地质参数反演和降深预测

在基坑排水和水源地开采时多为群井抽水,一般采用数值模拟的方法能够准确地反演水文地质参数及预测抽水后的降深,但数值模拟的方法对水文地质资料要求较高,建模和调参的过程繁琐,工作量较大。文章基于群井叠加原理提出一种水文地质参数反演的方法,结合VBA程序可预测抽水后任意时刻的流场。该方法适用于抽水孔距离较近、水文地质参数差异不大的承压含水层地区。将此方法应用于乌鲁木齐市地铁2号线某试验场地的群井抽水试验中,对比了试验的观测数据与计算结果,表明此方法能够有效地反演水文地质参数并能预测水源地开采后的地下水流场,为水文地质参数获取及计算提供了新方法,也为解决地下工程排水问题提供了新思路。     

基于MCMC和ES-MDA方法的地下水数值模型非均 质参数场及开采量的反演研究

马尔科夫链蒙特卡罗方法(MCMC)和多重数据同化集合平滑器方法(ES-MDA)近年来在地下水参数反演得到广泛应用，但对三维多层非均质含水层参数反演精度和计算效率还缺乏对比分析。本文构建了含有基于Karhunen-Loève展开的非均质参数场的潜水和多层承压水含水层案例，并建立了地下水数值模型和基于Kriging方法的替代模型，模拟含水层分层水头变化，探讨了基于替代模型的MCMC、替代模型和数值模型相结合的两阶段MCMC以及ES-MDA方法反演的含水层渗透系数以及开采量。结果表明，针对本文算例，在非均质参数和开采量的反演中，相比而言，两阶段MCMC反演参数精度更高，ES-MDA方法计算效率更高。本研究为地下水数值模型参数反演方法选择提供参考依据。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明:库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

Site modelling methods for detecting hydrologic alteration of flood frequency and flood duration in the floodplain below the carlyle dam,lower Kaskaskia River,Illinois, USA

Reports concerning the influence of dams on river hydrology vary among researchers, interest groups and government agencies. These often contradicting statements may occur because changes in hydrology caused by dams are distinct for each dam and river watershed. The objective of this research was to use site specific techniques to determine if the 1967 installation of the Carlyle Dam, lower Kaskaskia River, Illinois, altered flood frequency and duration within the forested floodplain located below the dam. Results indicated a decrease in flood duration and frequency, and a decrease in annual flood frequency variation at a site 6.4 km below the dam. Pre‐dam versus post‐dam differences in flood frequency and duration at the site 32.2 km below the dam were related to climate rather than dam effects. Although dam impacts are a concern, this research shows that distance downstream from the dam and downstream tributary and watershed characteristics should be considered before assuming that the dam has changed hydrologic parameters for portions of rivers. This research also indicates that areas of the lower Kaskaskia River may still maintain hydrologic ecological integrity, and could be targeted for restoration and adaptive management purposes. Hydrologic modelling combined with river gage and on‐site well measurement techniques presented in this study could provide detailed flood frequency and duration information for land use, sociological and geomorphological questions in focus areas within river floodplains. Copyright © 2008 John Wiley & Sons, Ltd.     

浅谈优化Vray渲染在制作三维场景的应用研究

用Vray三维渲染引擎来渲染三维场景,其质量和速度是由一些影响因素和参数设置决定的,不同的参数和因素,可以得出不同的三维渲染效果.因此,分析、优化三维渲染质量和速度的影响因素,正确、合理的选择参数对提高Vray最后渲染阶段的质量和速度非常重要.     

固结、渗流和沉积控制方程研究

本文从两相流体动力学的守恒方程出发，考虑固相、液相的相对运动，推导了可以考虑场的不均匀性和流体压缩性的统一形式的控制方程，并对方程所基于的物理概念和相互联系进行了必要的分析。通过对方程适当形式的表达，可导出用于大、小变形固结、渗流和沉积的简化方程，显示了在不同领域的三个理论存在一定的统一性。方程推导过程并未对本构关系加以限制，适用范围较广。依据实际问题的要求，作了不同形式的简化。     

四川省及重庆市中型水电站效益分析

该文分析了四川省及重庆市几座中型水电站的调查材料表明：四川省及重庆市中型水电站不仅在川渝主网和地方电网中起着很大的作用，并具有巨大的社会效益，同时还有综合利用效益，说明修建中型水电站的优越性．     

掺MgO混凝土的宏细观试验研究

利用MgO膨胀剂的延迟微膨胀效应能显著提高大体积混凝土的力学性能,产生的预压应力还能有效提高大体积混凝土抵抗温度开裂的能力,但目前对其微观机理研究不多。采用宏观与微观相结合的方式,研究了不同活性指数、不同掺量的MgO混凝土的力学性能,利用SEM/EDS微观分析手段揭示了MgO对混凝土性能影响的作用机理。试验结果表明:MgO取代部分水泥掺入混凝土中,混凝土的力学性能降低;掺量为4%～5%时,活性指数为100s的MgO混凝土的膨胀率大于活性指数为50 s的MgO混凝土;MgO混凝土的膨胀特性与Ca,Si,Mg,Al等元素的分布情况有关,掺入的MgO将改变界面区Ca,Si,Mg元素的富集特性,Ca元素和Mg元素更易于在界面区富集,导致混凝土宏观力学性能的降低。     

Statistical tools for thermal regime characterization at segment river scale: Case study of the Ste‐Marguerite River

Suitable thermal fish habitats are constrained by both maximum and minimum temperature tolerances. A multivariate and geostatistical approach was developed to estimate stream thermal characteristics at the river segment scale. Data from 22 temperature‐monitoring stations during summer 2007 were used to estimate monthly maximum temperature as well as thermal characteristics such as the number of events, the cumulative degree–days and the associated duration over specific temperature thresholds of 19 and 21°C. The probability of exceeding these temperature thresholds has also been interpolated. The methodology relies on the construction of a multivariate space using physiographic and hydrological characteristics of gauging stations as inputs in a canonical correlation analysis (CCA). A geostatistical interpolation technique, ordinary kriging, was subsequently used to perform interpolation in the physiographical space constructed using CCA. Results from this study were obtained for thermal characteristics estimated into two different interpolation spaces: (1) a 7 metrics space, and (2) an 8 metrics space. Cross‐validation technique has been performed and satisfactory results were obtained. Kriging thermal characteristics (magnitude and duration) into the 7 metric space for a 19°C threshold exceedance leads to best results with Relative Root Mean Square Error (RRMSE) ranging between 9.66 and 15.08%. The study shows that kriging in a multivariate space is a promising tool for water resources managers, especially in cases where risk mapping for lethal or sub‐lethal temperature thresholds may be required for a specific fish species. Copyright © 2010 John Wiley & Sons, Ltd.     

基于MIDAS软件探讨施工工序对深基坑稳定性的影响

基于武汉地铁名都站深基坑工程与水文地质勘察资料,建立了三维工程地质仿真计算模型。依据名都站深基坑开挖支护方案,利用有限元软件MIDAS的摩尔-库仑本构模型,对武汉地铁名都站深基坑施工过程中,不同施工工序下每步开挖之后,基坑的变形情况做仿真模拟计算,并对比分析其对基坑稳定性的影响。结果表明:基坑围护结构的变形情况与施工工序有很大的关系,施工工序越合理,上部土体变形越小,反之越大。因此,在基坑工程的施工过程中,要注重施工步骤的划分与合理安排,从而保证基坑工程的安全。研究成果为以后武汉地区基坑工程的施工设计提供了值得借鉴的经验。