中国和美国的推移质泥沙采样器野外比测试验

中国和美国已研制出多种推移质采样器 ,用以在变化范围很大的水流、泥沙条件下采样。由于采样器的设计原理不同和缺乏现场比测资料 ,这些采样器采样结果的可比性不明确。本文给出了五种采样器的输沙率及其它性能的现场比测结果。这五种采样器包括美国地质调查局设计的刚性框架的赫尔—斯密斯采样器 (以下称HS -1型 )和它的加大型 (以下称HS -1a型 )、沱特尔河TR -2型采样器以及中国长江水利委员会 (长江委 )研制的Y78-1型刚性框架采样器和Y80 -2型软底网式采样器。在美国各采样点比测HS -1型采样器的输沙率为Y78-1型的 3.0倍 ,而在中国比测的仅为 1 .2倍。两国比测点上流速和推移质粒度的明显差别可能是导致这一差异的原因 ,两国在采样技术和比测方法方面的差别也稍有影响。在中国的比测 ,HS -1a型测定的输沙率平均为Y80 -2型的 4.4倍 ,TR -2型测定的输沙率平均为Y80 -2型的 2 .2倍。比测过程中取得的经验有助于增加对推移质采样器设计特性的理解 ,并强调了使用不同设计的采样器来测定沙粒或较大的砾卵石泥沙的推移质输沙率是必要的。     

EKL型水文缆道设备观测资料的对比分析

近几年来,新疆伊犁水文水资源勘测局先后引进6台EKL型水文缆道设备,并分别应用于不同特性的河流,选择沙质河床和卵石河床组成断面的四个水文站进行测深、测宽及流量比测试验,通过对EKL设备的测深、测宽功能及流量实测资料进行统计分析计算,分析了该设备在沙质河床和卵石河床河流上的应用。通过分析得出:河床组成和河床质的分布对测深的影响较大,河床质粒和分布不同,对断面面积测验的影响不同,测宽误差对流量测验精度的影响不大。     

Overestimated cod values for raw wastewaters extracted by vacuum sampling devices due to sedimentation effects

Automatic vacuum sampling devices are frequently used to obtain representative samples of raw wastewaters. As a relatively high frequency of sampling is desired to cover the full range of load fluctuations and the volume of a composite sample is generally limited, the volume used from each sampling event is significantly less than that actually extracted by the sampler. On S different wastewater treatment plants the authors have found that the COD concentration in the sample volume used for analyses was significantly higher than that in the sample volume wasted by the vacuum sampler. It is hypothesized that the observed change in sample quality after the excess sample volume has been wasted is due to the sedimentation of solids in the sample chamber. This leads to a significant overestimation of the COD in subsequent analyses. Subsequent tests, where samples from vacuum samplers were compared with samples drawn by hand and by a scoop sampler respectively, support this hypothesis.     

陕西省大中型水库推移质淤积量的估算

提出了利用水库实测淤积量和水库上、下游水文测站泥沙测验成果估算水库推移质淤积量的方法 ,并用此法对我省石泉等七座大中型水库的推移质淤积量进行了估算分析。     

条件概率在推悬比统计分析中的应用

本文依据概率论原理，通过建立条件频率曲线的方法，论证推悬比的频率曲线，即悬移质发生的条件，相应推移有条件频率曲线。以长江新厂站实测资料例，对如何建立频率的曲线的工作程序，方法、图表等，作了详细说明，为泥沙工程中确定推移量、延长推移质系列、改进泥沙测验布局，提供了一个新方法。     

双峰型非均匀沙粗细颗粒相互作用对推移质输移的影响

为研究粗细颗粒间相互作用对非均匀沙输移的影响,采用推移质动态采集、图像识别和多普勒测速技术,实现了瞬时输沙量、颗粒组成与近壁脉动流速的实时同步监测。针对双峰型非均匀沙进行了211组推移质系列水槽试验,分析表明:推移质输移量与粗沙拣选度的随机波动与紊动猝发引起的流速脉动具有响应关系;推移质中细粒基本保持持续输移,而粗粒输移则具阵发性,并遵循促发、触发与失怙3种模式;颗粒组成结构对3种模式的实施过程有重要影响;它制约着泥沙中细粒对粗粒的激励、碰撞和解怙强度,使得推移质总沙、细沙和粗沙输移率随床沙组成的改变各自呈现出不同的变化规律;水流强度一定时,随床沙粗细比的减小,输沙率呈驼峰型曲线变化;只有适宜的粗细颗粒搭配(ηc)才能使非均匀推移质输沙率达到峰值,且大于该床沙组成中任一均匀沙的输沙率。     

Changes in benthic sediment in the thomson river,Southeastern Australia,during construction of the thomson dam

The particle-composition (0.15 to >64 mm) of the stream-bed was monitored by Surber sampling at sites above and below the site of the Thomson Dam during the two years of most active construction. Levels of particles between 0.5?2 mm were highest 9.5 km below the dam site, and increased throughout the study. Levels of these grades at sites above and well below the dam site were variable, but showed no consistent trends. Material greater than 2 mm showed no substantial variation either over time or between sites spanning approximately 70 km of river length and 250 m of elevation. Artificial substratum samplers were used to estimate the rate of sediment input (0-2 mm) between sampling dates. Sediment input was clearly highest 1 km and 9.5 km below the dam site. Input was seasonal, with maxima in winter and spring of each year. Size classes 1-2 mm and <0.063 mm contributed over 60 per cent of the total deposited sediment. Over the second year of the study, high levels of sediment <0.063 mm were deposited at a site 33 km below the dam site, indicating the progressive movement of material down the river. Some fine sediment was found to penetrate unconsolidated bed material to depths down to 60 cm. It is suggested that such material, resulting from land disturbance, is capable of filling interstitial spaces in the stream-bed, and that major disturbance of the bed may be necessary to dislodge it.     

An Estimation of the Suspended Sediment Load Using Adaptive Network Based Fuzzy Inference System,Support Vector Machine and Artificial Neural Network Models

Sediment transport in streams and rivers takes two forms as suspended load and bed load. Suspended load comprises sand + silt + clay-sized particles that are held in suspension due to the turbulence and will only settle when the stream velocity decreases, such as when the streambed becomes flatter, or the streamflow into a pond or lake. The sources of the suspended sediments are the sediments transported from the river basin by runoff or wind and the eroded sediments of the river bed and banks. Suspended-sediment load is a key indicator for assessing the effect of land use changes, water quality studies and engineering practices in watercourses. Measuring suspended sediment in streams is real sampling and the collection process is both complex and expensive. In recent years, artificial intelligence methods have been used as a predictor for hydrological phenomenon namely to estimate the amount of suspended sediment. In this paper the abilities of Support Vector Machine (SVM), Artificial Neural Networks (ANNs) and Adaptive Network Based Fuzzy Inference System (ANFIS) models among the artificial intelligence methods have been investigated to estimate the suspended sediment load (SSL) in Ispir Bridge gauging station on Coruh River (station number: 2316). Coruh River is located in the northern east part of Turkey and it is one of the world”s the fastest, the deepest and the largest rivers of the Coruh Basin. In this study, in order to estimate the suspended sediment load, different combinations of the streamflow and the SSL were used as the model inputs. Its results accuracy was compared with the results of conventional correlation coefficient analysis between input and output variables and the best combination was identified. Finally, in order to predict SSL, the SVM, ANFIS and various ANNs models were used. The reliability of SVM, ANFIS and ANN models were determined based on performance criteria such as Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Efficiency Coefficient (EC) and Determination Coefficient (R²).     

风化基岩抗压强度统计分析研究与探讨

随着超大型荷载工程项目增多,利用基岩作为深基础或浅基础持力层,且混凝土强度增大,对基岩承载力准确性判断要求更高,准确提供基岩承载力值就显得尤为重要.如何把握好从钻探、取样、试验、成果统计等多方面是岩土工程师具备的基本素质.结合哈尔滨市三环路西线跨松花江大桥工程风化基岩,研究了哈尔滨地区松花江漫滩场地基岩承载力标准值的确...     

Analysis of Bed Load Equations and River Bed Level Variations Using Basin-Scale Process-Based Modelling Approach

Bed load transport is a key process in maintaining the dynamically stable channel geometry for restoring the form and function of river ecosystems. Bed load consists of relatively large sediment particles that are moved along the streambed by rolling, sliding or saltation. Currently, various empirical correlations are used to estimate bed load transport rates since no single procedure, whether theoretical or empirical, has yet to be universally accepted as completely satisfactory in this aspect. Bed load particles are primarily sourced from river bed materials or banks. The amount of bed load and its spatial distribution contributes significantly to river bed level changes. Hillslope sediment contribution, mostly available to the river in the form of suspended load, also plays an important role in river bed level changes. This study aims to analyse different bed load equations and the resultant computations of river bed level variations using a process-based sediment dynamic model. Analyses have revealed that different bed load equations were mainly deduced from the concept of relating bed shear stresses to their critical values which are highly factored by the slope gradient, water discharge and particle sizes. In this study, river bed level variations are calculated by estimating total surplus or deficit sediment loads (suspended loads and bed loads) in a channel section. This paper describes the application of different widely used bed load equations, and evaluation of their various parameters and relative performances for a case study area (Abukuma River Basin, Japan) using a basin-scale process-based modelling approach. Relative performances of river bed level simulations obtained by using different bed load equations are also presented. This paper elaborates on the modelling approaches for river bed load and bed level simulations. Although verifications were not done due to unavailability of field data for bed load, qualitative evaluations were conducted vis-à-vis field data on flow and suspended sediment loads as well as the bed loads presented in different past studies.     

Predicting bed load transport of sand and gravel on Goodwin Creek

Bed load transport rates are difficult to predict in channels with bed material composed of sand and gravel mixtures. The transport of bed load was measured on Goodwin Creek, and in a laboratory flume channel with a similar bed material size distribution. The range of bed load transport rates measured in the laboratory channel were similar to those measured in the channel of Goodwin Creek; however, the shear stresses calculated on Goodwin Creek were three times greater than in the laboratory channel for similar bed load transport rates. Much of this difference in shear stress was removed by applying the drag partitioning technique of Einstein, although significant differences between the two sets of data remain. Predictions of bed load transport rates using three previously published transport relations were good for most flows for the laboratory data. For the Goodwin Creek bed load data, predicted transport rates were close to measured ones for low flows but diverged by an order of magnitude or more for high shear stresses. Improved methods of shear stress partitioning are needed to improve the performance of bed load transport relations on streams of this type.     

Evaluation of suspended load transport rate using transport formulas and artificial neural network models （Case study： Chelchay Catchment）＊

Accurate estimation of sediment load or transport rate is very important to a wide range of water resources projects. This study was undertaken to determine the most appropriate model to predict suspended load in the Chelchay Watershed, northeast of Iran. In total, 59 data series were collected from four gravel bed-rivers and a sand bed river and two depth integrating suspended load samplers to evaluate nine suspended load formulas and feed forward backpropagation Artificial Neural Network (ANN) structures. Although the Chang formula with higher correlation coefficient (r = 0.69) and lower Root Mean Square Error (RMSE = 0.013) is the best suspended load predictor among the nine studied formulas, the ANN models significantly outperform traditional suspended load formulas and show their superior performance for all statistical parameters. Among different ANN structures two models including 4 inputs, 4 hidden and one output neurons, and 4 inputs, 4 and one hidden and one output neurons provide the best simulation with the RMSE values of 0.0009 and 0.001, respectively.     

Einstein推移质公式的改进研究

很多学者对Ｅｉｎｓｔｅｉｎ推移公式建立过程中的冲刷概率，泥沙无因次单步运行蹁和泥沙交换时间等方面进行了深入研究与改进，并得到了改进后的推移质输沙率公式。     

"戽底设窄缝混合消能"在桥巩水电站低坝的应用

收缩式消能工与挑流、底流、戽流相联合的消能方式，在高坝上已获得广泛应用，最近将其应用到中坝上，也取得良好效果。红水河桥巩水电站低坝，作了把收缩式消能工用在低坝戽式消力池里进行混合消能的尝试．水工模型验证结果表明，同样取得显著的消能效果，还使消力戽具有自我清理推移质的能力。     

悬移质涡管排沙分析

涡管排沙措施以前主要是解决推移质泥沙问题。本通过对悬移质涡管排沙的近似分析，建立了悬移质涡管排沙分流比与截沙率之间的关系，并指出了其适用范围，从而将涡管排沙技术由解决推移质问题扩展到解决悬移质泥沙问题，试验基本上验证了理论分析结果。为了提高悬移质涡管排沙效果，中还建议了几项技术措施。     

蒋家沟流域非泥石流活动期的输沙特征

实测2008—2009年间蒋家沟非泥石流时期推移质和悬移质的总量,分析非泥石流时期蒋家沟的输沙特征,结果表明:非泥石流活动期推移质含量极大,年输沙量达3.6万t,相当于一次中等规模泥石流的固体物质总量;泥石流对推移质和悬移质含量影响很大,泥石流之后,河道内悬移质和推移质含量呈衰减趋势,其中悬移质呈负幂指数衰减y=y0exp(-bx),推移质衰减速度大于悬移质;推移质粒径范围雨季和旱季差别较大,悬移质则相对一致,悬移质和推移质粒径分布均满足对数高斯分布y=aexp(-(x-b)2/c2);悬移质具有良好的分形特征,能得到其分维值范围,并确定悬移质分形的无标度区的界限,即划分床沙质和冲泻质的临界粒径为16μm,大于和小于该粒径的颗粒组成均具有较好的分形特征。     

长江河口涨潮槽泥沙运动规律

30年来，在对涨潮槽性质和水沙条件有所了解的基础上，于2001年洪季和2003年枯季又一次对长江口新桥水道和南小泓两条典型涨潮槽及与其相邻的南支和南港主槽(落潮槽)的水流、泥沙和河床沉积物进行观测，并进行了专题研究。结果表明：潮流历时涨潮比落潮短；潮流和单宽潮量涨潮比落潮大，优势流小于50％，净水流向槽顶方向：涨潮含沙量、单宽输沙量大于落潮，优势沙小于50％，净输沙向槽顶方向；悬沙粒径组成较细，河床泥沙粒径组成较粗，河床存在推移质泥沙运动，并形成微地貌沙波。     

赣江中下游河道床沙分析

本文通过赣江中下游河道普遍的床沙取样和实地调查,对河床组成、地貌形态及其与泥沙运动的关系进行了分析,指出了推移质运动在赣江江心洲分汊河道形成中的重要性,对研究分汊河道成因有一定的参考作用。     

沙波运动与推移质输沙率

本文依据沙波运动尺度，从沙波运动角度建立了推移质输沙率表达式，该式既能用于均匀沙又能用于非均匀沙的输沙率计算，并经百余组室内外实测资料的验证，同时与其他公式进行了对比，结果表明，在各种强度的输沙情况下都能较好的吻合。     

Auswirkungen von Baggerungen und Verklappungen hochwasserbedingter Feinsedimentablagerungen am Fallbeispiel Winterhafen Linz/Donau

In the case study “Winterhafen Linz” the effects of dredging/excavating fine sediments previously deposited by flood events and their subsequent dumping into the Danube mainstream were investigated. While this maintenance work was in progress, the temporal and spatial extent of the sediment plume and the changes in bed topography were measured. By employing air-lift samplers and grab samplers in the dredging and dumping areas, the question as to whether, and if so to what extent, the benthic invertebrate community was disturbed by the maintenance work. It could be clearly demonstrated that the sediment dredging severely affected the benthic invertebrates (an 82 % decline in biomass), while the dumping of the material had no effects on the Danube biota. Numerical modeling was used to simulate discharges and dumping locations other than those actually encountered during the monitoring campaign, thus making it possible to extrapolate and draw conclusions beyond the concrete results. These findings in turn provided the basis for recommendations on how to optimize dredging and dumping procedures on the Danube in future.