渗渠产水量与滤管开孔率的关系研究

渗渠是一种传统的取水方式,广泛应用于生产和生活中。产水量是渗渠设计的重要指标。结合渗渠取水常用公式,在其他条件一定的情况下,就渗渠滤管开孔率对渗渠产水量的影响进行分析,得出相应的关系曲线图,拟合出渗渠产水量与滤管开孔率的经验公式。     

滤管长度对渗渠产水量的影响

渗渠取水作为一种传统的取水方式,广泛地应用于工农业生产和日常生活中,因而对渗渠产水量影响因素的研究就尤为重要.滤管长度是影响渗渠产水量的重要因素之一,将采用室内模型试验的方法,根据试验所得数据点绘出滤管长度与渗渠产水量关系图,对滤管长度与渗渠产水量的关系进行定量分析.提出渗渠滤管长径比、产水量比的概念,确定了渗渠滤管长宽比与产水量比的经验公式,可供实际工程参考.     

支流水沙作用下干流床面冲淤特征试验研究

 通过一系列的水槽试验,研究了交汇角为30°时不同水沙条件下干流床面冲淤特性,获得了在支流有无来水、来沙时不同主支汇流比下的干流床面冲淤二维等值线图,初步揭示了干流床面冲淤随主支流量比及支流是否来沙的变化特性。研究成果对了解交汇区的冲淤变化及河床演变具有积极的作用。     

西塞山电厂取水口河段河床冲淤研究

电厂取水口布置和正常运用受到所在河段河床冲淤变化的直接影响.对西塞山电厂二期工程取水口河段近期冲淤进行了分析,并讨论了取水口局部河床冲淤变化可能对工程带来的影响.结果表明:取水口河段近几十年来河床冲淤交替,无明显单向变化.回流区内虽有一定的冲淤变化,但在多数情况下不会给电厂取水设施造成影响,近岸取水基本可行.但为避免极少数年份回流区泥沙淤积较大,建议取水口进水底槛高程适当上提,同时将取水口平面位置向江心外移.     

明渠水沙条件对渗渠产水量影响分析

针对渗渠取水过程中明渠水沙条件对渗渠产水量的影响,结合模型试验,运用泥沙运动力学理论研究分析了同种来水量、不同水深条件下明渠水流泥沙运动变化,以及由此引起渗渠产水量变化的情况。试验结果表明:水流能保持一定的流速,满足明渠水流含沙颗粒推移运动并实现泥沙颗粒向下游输送的条件,就可以避免渗渠反滤层结构的改变以及渗透系数的减小,从根本上防止反滤层淤塞,避免反滤层翻修,实现渗渠工程的长期安全正常运行。     

淤泥质河床冲淤分析计算

根据床面剪切力和水流挟沙力对床面冲淤的影响,针对处于冲淤平衡状态下的床面,利用权重法建立了剪切力和水流挟沙力共同作用下的床面冲淤计算公式,可以广泛地应用于淤泥质河床的冲淤计算。采用剪切力、挟沙力以及二者所引起床面冲淤率的比值等3个参数,整理得出床面冲淤类型,用以分析床面冲淤形态和床面冲淤特点。通过开敞航道淤积、顺岸式港池冲淤以及滩面流速改变引起的床面演变等3个实例,说明本研究成果有较好的实用价值。     

黄河班多水电站渗渠的设计与计算

黄河班多水电站施工供水系统采用渗渠取水,渗渠设计产水量为1 620 m~3/h.介绍了这种取水方式的设计思路和具体计算方法,以及进水孔、检查井和渗渠接口的设计特色.     

180°弯曲水槽内床面冲淤演化过程数值模拟

为准确掌握180°弯曲水槽内床面冲淤特征及其演化过程,采用基于非结构化三角形网格的三维流动和地形冲淤数值模型对180°弯曲水槽内床面的冲淤演化过程进行复演。运用标准k-ε紊流模型和显式2步投影方法求解RANS方程,推移质输沙率选取VanRijn输沙公式计算,对于二次流强度较强、横向坡度对输沙方向影响较大的强弯曲水槽,采用方便实用的Engelund方法计算横向底坡所引起的输沙方向的偏移,同时对河床变形所引起的河床临界起动切应力变化进行修正及对流动和地形冲淤相同时间步模拟非恒定的河床冲淤演化过程。与试验测量结果对比显示数值模型对强弯曲水槽冲淤特征有较好的模拟效果;Engelund方法对计算输沙方向偏移角度具有明显的改进;模型同样也具备复演内床面非恒定冲淤演化过程的能力。     

集取地表水渗渠取水量影响因素探讨

取水量是否达到设计要求是衡量渗渠成功与否的指标,而影响渗渠取水量的因素是多方面的。结合渗渠取水常用公式,就渗渠上部明渠水深、含水层渗透特性以及渗渠的结构尺寸等因素对其取水量的影响进行了分析:渗渠上部明渠水流深度的变化会改变渗渠取水时的有效水头;反滤层的渗透特性和能力直接决定渗渠的出水水质和取水量;渗渠结构尺寸和埋设方式的合理选择是关键。     

河床浅层地下水取水相关问题探究

本文以江西省广昌县水厂的取水工程为例,分别对渗渠、辐射井、以及大口井+渗渠这三种河床浅层地下水的取水方式进行了布置、结构设计和进水量计算。通过比较分析,大口井+渗渠取水方式的进水效果较好,平面布置更符合河道特点,并对其进行了优化。     

联合取水技术在江水源热泵中的应用

江水源热泵系统以江水作为热泵系统的热源为建筑物供热或供冷,在建设节约型社会、国家节能减排的形式下,在沿江有条件的地区已推广使用。该文通过重庆江北城CBD天然河床渗滤＋人工河床渗滤＋直取水联合取水工程,提出了一种适合江水源热泵的取水技术。     

联合取水技术在江水源热泵中的应用

江水源热泵系统以江水作为热泵系统的热源为建筑物供热或供冷,在建设节约型社会、国家节能减排的形式下,在沿江有条件的地区已推广使用.该文通过重庆江北城CBD天然河床渗滤+人工.河床渗滤+直取水联合取水工程,提出了一种适合江水源热泵的取水技术.     

On the process of fine sediment infiltration into static gravel bed: A CFD–DEM modelling perspective

The gravel bed clogging, caused by infiltration and accumulation of fine sediment, degrades the river ecology. A proper understanding of the infiltration process, and underlying mechanism and causes, are necessary to take preventive measures. The process of fine sediment infiltration into static gravel bed is studied by distinguishing between bridging and percolation behaviours, as they affect the river ecology and physical processes occurring in the river system differently. However, several contradicting observations, concerning their occurrences, are reported. We employed the unresolved CFD–DEM method to simulate and investigate the infiltration process. The theoretical size ratios, corresponding to different geometrical configurations for a binary mixture of mono-disperse spherical particles, representing bridging and percolation processes, are considered and simulated with and without flowing water effects. The effects of several turbulence models on the infiltration process are also studied. We found that fine sediment infiltration in fluvial deposits is mainly gravity-dominated, supporting Cui's hypothesis that fine sediment infiltration through intra-gravel flow is similar to fine sediment infiltration driven by gravity. In contrast to consensus in the field, our results demonstrate that the occurrences of different infiltration processes (bridging and percolation) seem to be independent of gravel bed thickness, rather depend only on the relative grain size distribution of fine sediment and gravel. However, a precise definition of a ‘thick enough’ gravel bed is necessary to distinguish between bridging and percolation behaviours. Here, we hypothesize a suitable gravel bed thickness, which might be regarded as a ‘thick enough’ gravel bed.     

滹沱河大型入渗试验地下水补给量计算

通过采用水均衡法计算了滹沱河入渗试验期间的河道入渗补给量,并求取了滹沱河水源地一带获得的河道入渗补给量。研究表明:试验期间河道入渗水量为1 482.75万m3,河道入渗补给地下水量为1 382.89万m3,河道渗漏补给系数为93%;滹沱河水源地接受的补给量为742.53万m3,水源地范围内的观测井最大水位上升幅度6.823m,地下水补给效果明显。     

FINE SEDIMENT INFILTRATION DYNAMICS IN A GRAVEL‐BED RIVER FOLLOWING A SEDIMENT PULSE

Pulses of fine sediment in gravel‐bedded rivers can cause extensive fine sediment infiltration (FSI) into void spaces in coarse bed material, potentially altering river morphodynamics and aquatic ecosystems. Previous work suggests a conceptual model of FSI whereby FSI occurs to a limited depth as a function of the relative grain size of bed sediment compared with infiltrating sediment and is influenced by fine sediment supply and local flow dynamics. Our study applies this conceptual model to a complex reach of a wandering, medium‐sized, gravel‐bed river to investigate the spatial and temporal controls on FSI. To constrain the timing of FSI, we use the release of contaminated sediment from an upstream dam removal and complementary field methods (bulk sampling, freeze cores and infiltration bags) to capture sediment across varied depositional settings. Our results indicate that, even in a morphologically complex reach, fine‐sediment content in the bed does not vary significantly among deposition settings or vertically below the bed surface. We also found that the most contaminated fine sediments released into our study river by a dam removal are not present within the bed material and that substrate has likely been reworked over the period between the release of contaminated sediment and sampling. Our observations also suggest that seals of fine sediment causing void pore space at depth, which have previously been associated with FSI, are not evident in our field area. This suggests that in natural systems, high sediment supply and mobile beds may limit seal formation and persistence. Copyright © 2013 John Wiley & Sons, Ltd.     

考虑下渗的河道与蓄滞洪区洪水演进过程模拟

基于霍顿(Horton)下渗和有限体积法,建立了考虑动态下渗的一二维耦合水动力学模型,并选择海河流域漳卫河系与大名泛区联合防洪体系作为典型应用区域,利用典型场次洪水对河道模型进行了率定和验证,同时探讨了下渗对于河道行洪、蓄滞洪区分洪以及洪水演进过程的影响。结果表明:考虑动态下渗的河道模型具有较高模拟精度,3场典型洪水洪峰误差都在10%以内;河道下渗会明显推迟蓄滞洪区的启用时间,并减小分洪流量和洪水总量;蓄滞洪区下渗对分洪过程影响较小,但会加快蓄滞洪区的退水速度。     

Environmental and biological responses of former channels to river incision: A diachronic study on the upper rhǒne river

The impacts of river incision should be a lowering of the river level, which would increase the rate of water flow from the hillslope aquifer to the river and its former channels. If this aquifer is nutrient-poor, it should favour the oligotrophication of the former channels. However, if the lowering of the water-table exceeds the depth of the former channels, then it should lead to the drainage of these channels. These hypotheses were tested on two former channels located in a degrading reach of the Rhǒne River (France); the former channels were influenced by floods, seepage water from the river and hillslope groundwater in 1989. The rate of river incision in this reach has increased since 1980 because of gravel extraction from the river bed (0.5 m between 1989 and 1993). Between 1989 and 1993, the reduction of river infiltration and the increase in the amount of water from the hillslope aquifer in the former channels were demonstrated by the decrease in the phosphate and ammonia content of the water, and its increased alkalinity and conductivity. The responses of aquatic vegetation to river incision depended on the vegetation zone investigated. Two floristic zones that were frequently flooded and species-poor in 1989 remained species-poor in 1993. Two floristic zones, which were species-rich and patchily organized, became dry or very shallow in 1993; as a consequence, aquatic vegetation disappeared, and was replaced by helophytes and terrestrial species. In the last vegetation zone, the increase in the amount of water coming from the hillslope aquifer caused the appearance and development of Chara hispida, an oligotraphent species. Unforeseen impacts of river incision were a decrease in the spatial and temporal heterogeneity of the former channels and lower aquatic macrophyte richness.     

南水北调引江济汉工程取水口位置比选研究

重点研究了南水北调引江济汉工程后三峡水库运用50年内,不同取水口河段泥沙冲淤、河势、水位的变化趋势,为合理选择进水口提供了科学依据。研究成果表明,由于三峡水库的拦沙及调节作用,改变了下游河道的来水来沙条件,使下游河段冲淤发生变化,河床处在不断调整过程中。在三峡水库运用50年内,各取水口河段河床冲刷主要集中在前10年,随后出现冲淤平衡、淤积等。兴建取水口工程后,工程对河段上、下游的影响是有限的,但其影响仅限于工程附近;各取水口的取水条件,均呈现出随着三峡水库运用年限的增加而发生变化。     

考虑径流补给的滑坡渗流三维有限元模拟

现有数值模拟方法在模拟边坡降雨入渗时通常不能考虑径流流量补给对滑体渗流的影响,当滑床和滑带的渗透性相对于滑体极低时,会出现低估降雨入渗量、高估滑坡稳定性的现象。以Richards方程、运动波方程和有限元法为基础,提出了一种降雨时滑坡渗流数值模拟方法。该方法忽略滑床和滑带的渗流而只考虑滑体渗流过程,从而减小计算规模,也避免了因滑体与滑床(滑带)渗透性差异过大引起的数值计算困难;依据地形和滑体降雨入渗边界饱和情况,修正降雨入渗边界类型和流量,实现了考虑径流流量补给的滑坡降雨入渗简化数值模拟。对简单土质边坡降雨入渗进行数值模拟,从水量平衡与边坡渗流场两个角度,对比了考虑和不考虑径流流量补给的区别;结果表明,考虑径流流量补给时才能保证计算结果水量平衡,正确反映降雨入渗对基质吸力大幅降低的作用。