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Sediment transport capacity of hyperconcentrated flow

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 961-975页

作者： SHU AnPing1,2 & FEI XiangJun2 1 School of Environment & key laboratory of Water and Sediment Sciences,Ministry of Education,beijing Normal university,beijing 100875,china 2 state key laboratory of hydroscience and engineering,tsinghua university,beijing 100084,china School of Environment & key laboratory of Water and Sediment Sciences Ministry of Education Beijing Normal University Beijing 100875 China state key laboratory of hydroscience and engineering Tsinghua University Beijing 100084 China

As one of the most important components of river mechanics,sediment transport capacity of sediment-laden flows has attracted much attention from many researchers working on river mechanics and hydraulic engineering. Based on the time-averaged equation for a turbulent energy equilibrium in solid and liquid two-phase flow,an expression for the efficiency coefficient of suspended load movement was derived for the two-dimensional,steady,uniform,fully-developed turbulent flow. A new structural expression of sediment transport capacity was achieved. Using 115 runs of flume experimental data,which were obtained through two kinds of sediment transport experiments in the state of equilibrium,in combination with the basic rheological and sediment transporting characteristics of hyperconcentrated flow,the main parameters in the structural expression of sediment transport capacity were calibrated,and a new formula of sediment transport capacity for hyperconcentrated flow was developed. A large amount of field data from the Yellow River,Wuding River,and Yangtze River,etc. were adopted to verify the new formula and good agreement was obtained. These results above contribute to an improved theoretical system of river mechanics and a reliable tool for management of rivers carrying high concentration of sediments.

关键词： hyperconcentrated flow turbulent energy equilibrium efficiency coefficient sediment transport capacity

Effects of fluvial processes and human activities on stream macro-invertebrates

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International Journal of Sediment Research 2011年第4期26卷 416-430页

作者： Xue-hua DUAN,Zhao-Yin WANG,and Meng-zhen XU 1 Ph.D.,state key laboratory of hydroscience and engineering,tsinghua university,beijing 100084,china Jiangyin Water Conservancy and Farm Machinery Bureau,Jiangyin 214431 china, 2 Prof,state key laboratory of hydroscience and engineering,tsinghua university,beijing 100084,china, 3 Doctoral candidate,state key laboratory of hydroscience and engineering,tsinghua university,beijing 100084,china, [a] Ph.D. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Jiangyin Water Conservancy and Farm Machinery Bureau Jiangyin 214431 China Tel: 86-*** (M) [b] Prof. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China [c] Doctoral candidate State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

Benthic macro-invertebrates are vital components of river *** effects of fluvial processes and human activities on the distribution of macro-invertebrates were studied through field investigations and ***-one sampling sites on 31 rivers in china were selected to investigate the structures of macro-invertebrate *** rivers,according to their fluvial conditions,are classified as streams with a stable channel bed,degrading channel bed,aggrading channel bed,and intensive bed load *** structures of macro-invertebrate fauna for the four types of rivers are very *** rivers have a large number of individuals,abundant fauna, and high biodiversity;while the density and taxa richness for degrading rivers are small,and those for aggrading rivers are much less;whereas the ecology of rivers with intensive bed load motion are the *** paper proposes that streambed stability is the primary influential factor shaping the structure of benthic macro-invertebrate *** pollution can obviously result in the decrease of biodiversity,in the simplification of macro-invertebrate structures,and in the distortion of functional feeding group *** a river with high total nitrogen content,the relative abundance of collector-gatherers is high,and that of collector-filterers,scrapers,shredders,and predators are ***,shredders,and predators disappear in severely polluted *** isolation of aquatic habitat results in a distinct decrease of individual numbers and taxa *** result demonstrates that the connectivity of aquatic habitat significantly affects macro-invertebrate assemblages.A practical method to calculate a Habitat Suitability Index(HSI) is proposed,integrating the effects of the primary physical(including biotic and abiotic) and chemical *** biodiversity and taxa richness increase non-linearly with HSI.

关键词： Macro-invertebrate Streambed stability Substratum Isolation Habitat suitability Water pollution

Effect of streambed sediment on benthic ecology

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International Journal of Sediment Research 2009年第3期24卷 325-338页

作者： Xuehua DUAN1, Zhao-Yin WANG2, Mengzhen XU3, and Kang ZHANG41 Ph.D., Jiangyin Environmental Monitoring Station, Jiangyin 214431, china, Dept. of Hydraulic engineering, tsinghua university,2 Prof., state key laboratory of hydroscience and engineering, tsinghua university, beijing 100084, china, 3 Doctoral candidate, state key laboratory of hydroscience and engineering, tsinghua university, beijing 100084, china,4 Doctoral candidate, state key laboratory of hydroscience and engineering, tsinghua university, beijing 100084, china [a] Ph.D. Jiangyin Environmental Monitoring Station Jiangyin 214431 china Dept. of Hydraulic engineering tsinghua university [b] Prof. state key laboratory of hydroscience and engineering tsinghua university beijing 100084 china Tel: 86-10-62773448(O) [c] Doctoral candidate state key laboratory of hydroscience and engineering tsinghua university beijing 100084 china [d] Doctoral candidate state key laboratory of hydroscience and engineering tsinghua university beijing 100084 china

Benthic macroinvertebrates have been commonly used as indicator species for assessment of aquatic ecology. Streambed sediment, or substrate, plays an important role in habitat conditions for macroinvertebrate communities. Field investigations were done to study the benthic diversity and macroinvertebrate compositions in various stream substrata. Sampling sites with different bed sediment, latitude, and climate were selected along the Yangtze River, the Yellow River, the East River, and the Juma River, in china. The results show that benthic community structures found in different substrata clearly differ, while those found in substrata of similar composition and flow conditions but in different macroclimates are similar. The study, thus, demonstrates that the benthic macroinvertebrate community is mainly affected by substrate composition and flow conditions, but is generally unaffected by latitudinal position and macroclimate. Taxa richness of the macroinvertebrate community was found to be the highest on hydrophyte-covered cobbles, high on moss-covered bedrock, and low on clay beds and cobble beds devoid of plant biomass. Sandy beds are compact and unstable, thus, no benthic macroinvertebrates were found colonizing such substrata. Aquatic insects account for most of the macroinvertebrates collected in these rivers. Different insects dominate in different types of substrata: mainly EPT species (Ephemeroptera, Plecoptera, Trichoptera) in cobble, gravel, and moss-covered bedrock; and Chironomidae larvae in clay beds. The relation between the number of species in the samples and the size of the sampling area fits a power function of the species area. One square meter (1m2) is suggested as the minimum sampling area. A substrate suitability index is proposed by integrating the suitability of sediment, periphyton, and benthic organic materials for macroinvertebrates. The biodiversity of macroinvertebrates increases linearly with the substrate suitability index. Benthic ta

关键词： Streambed sediment Macroinvertebrates Benthic ecology Substrate suitability Biodiversity

A multiphase mesostructure mechanics approach to the study of the fracture-damage behavior of concrete

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Science china(Technological Sciences) 2008年第S2期51卷 8-24页

作者： TANG XinWei1,ZHANG ChuHan1 & SHI JianJun2 1 state key laboratory of hydroscience and engineering,tsinghua university,beijing 100084,china 2 Department of Urban Construction,Nanhua university,Hengyang 421001,china 1. state key laboratory of hydroscience and engineering Tsinghua University Beijing 100084 China 2. Department of Urban Construction Nanhua University Hengyang 421001 China

A multiphase mesostructure mechanical model is proposed to study the deformation and failure process of concrete considering its heterogeneity at the meso scopic ***,concrete is taken as a type of three-component composite material composed of mortar matrix,aggregates and interfaces on the ***,an efficient approach to the disposition of aggregates of concrete and a state matrix method to generate mesh coordinates for aggregates are ***,based on the nonlinear continuum damage mechanics,a meso-scale finite element model is presented with damage softening stress-strain relationship for describing the mechanical behavior of different components of *** this method,heterogeneities of each component in the concrete are considered by assuming the material properties of three components conform to the Weibull distribution ***,based on this multiphase meso-mechanics model,a simulation analysis of fracture behavior of a rock-fill concrete(RFC) beam is *** study includes experimental tests for determining basic mechanical parameters of three components of RFC and four-point flexural beam tests for verification of the *** is preliminarily shown that the numerical model is applicable to studying failure mechanisms and process of concrete type material.

关键词： concrete multiphase mesostructure mechanics numerical simulation experimental research

Experimental study on three dimensional movements of particles Ⅱ Effects of particle diameter on turbulence characteristics

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International Journal of Sediment Research 2009年第2期24卷 169-176页

作者： Limo TANG1 and Xingkui WANG2 1state key laboratory of Hydrology-Water Resources and Hydraulic engineering,Hohai university, Nanjing 210098,china 2 Prof.,state key laboratory of hydroscience and engineering,tsinghua university,beijing 100084,china state key laboratory of Hydrology-Water Resources and Hydraulic engineering Hohai University Nanjing 210098 China state key laboratory of hydroscience and engineering Tsinghua University Beijing 100084 China

Based on the 3D PTV(Particle Tracking Velocimetry) measuring system,the 3D movement characteristics of particles with four different diameters were investigated. Under specific flow conditions,the impact of particle diameters on 3D motion of particles was studied,and the turbulence characteristics were analyzed by different statistical methods. The results showed that the turbulence intensity of coarse particle decreased as the diameter increased. In near wall region,the probability density distributions of longitudinal and vertical fluctuation velocities both deviated from the normal distribution;while in the outer region,the probability density distribution of vertical fluctuation velocity approximately agreed with the normal distribution.

关键词： Particle diameter Turbulence Probability density distribution

Daily optimized model for long-term operation of the Three Gorges-Gezhouba Cascade Power Stations

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Science china(Technological Sciences) 2007年第z1期50卷 98-110页

作者： CAO GuangJing1, CAI ZhiGuo1?, LIU ZhiWu1 & WANG GuangQian2 1 china Three Gorges Project Corporation, Yichang 443002, china 2 state key laboratory of hydroscience and engineering, tsinghua university, beijing 100084, china china Three Gorges Project Corporation Yichang 443002 China state key laboratory of hydroscience and engineering Tsinghua University Beijing 100084 China

This paper presents the step-by-step genetic algorithm based on artificial intelligence guidance and builds a long-term daily optimized operating model for the Three Gorges-Gezhouba Hydropower Complex with single generating set as the based operating unit. Actual operating data from 2004 to 2006 are used to verify the model, and results show that the simulation accuracy determined by measuring the total amount of cascade power generation reaches 99.66%. Statistic hydrological data of normal years and actual data of three years of 2004―2006 are respectively used to perform an optimized prediction of the power generation process and benefits in future when the water stored in the TGP Reservoir reaches 175 m level and power generation benefits under different operation modes, such as delayed subsiding water level, advance water storage, and adopting of different flood-limited water levels, are forecasted. In the case of years with normal inflows, the total amount of cascade power generation running on current specifications reaches 107500 GWh per year. If the commencement of water storage after the flood season is moved forward by 20 days, the amount of power generation can be increased by 3400 GWh per year. If the limited water level in the flood season is raised by three to five meters, the amount of power generation can be increased by 1600 to 3200 GWh per year. If the commencement of water storage is moved forward while the maximum water level allowed in the flood season is raised, the amount of power generation can be increased by 6400 GWh per year.

关键词： cascade operation Three Gorges Project genetic algorithm optimization forecast

Physically-based approach to analyze rainfall-triggered landslide using hydraulic gradient as slide direction

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Journal of Zhejiang university-Science A(Applied Physics & engineering) 2012年第12期13卷 943-957页

作者： Qi-hua RAN1,Dan-yang SU1,Qun QIAN1,Xu-dong FU2,Guang-qian WANG1,2,Zhi-guo HE3 (1Department of Hydraulic engineering,Zhejiang university,Hangzhou 310058,china) (2state key laboratory of hydroscience and engineering,tsinghua university,beijing 100084,china) (3Department of Ocean Science and engineering,Zhejiang university,Hangzhou 310058,china) 1. Department of Hydraulic engineering Zhejiang University Hangzhou 310058 China 2. state key laboratory of hydroscience and engineering Tsinghua University Beijing 100084 China 3. Department of Ocean Science and engineering Zhejiang University Hangzhou 310058 China

An infinite slope stability numerical model driven by the comprehensive physically-based integrated hydrology model(InHM) is *** this approach,the failure plane is assumed to be parallel to the hydraulic gradient instead of the slope *** method helps with irregularities in complex terrain since depressions and flat areas are allowed in the *** present model has been tested for two synthetic single slopes and a small catchment in the Mettman Ridge study area in Oregon,United states,to estimate the shallow landslide *** results show that the present approach can reduce the simulation error of hydrological factors caused by the rolling topography and depressions,and is capable of estimating spatial-temporal variations for landslide susceptibilities at simple slopes as well as at catchment scale,providing a valuable tool for the prediction of shallow landslides.

关键词： Shallow landslide Infinite slope stability model Hydraulic gradient Physically-based hydrology model Integrated hydrology model(InHM)

Deterioration Mechanisms of Sulfate Attack on Concrete under Alternate Action

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Journal of Wuhan university of Technology(Materials Science) 2010年第2期25卷 355-359页

作者：高润东 state key laboratory of hydroscience and engineering Tsinghua University

By micro- and macro-observations, the deterioration mechanisms of concrete under alternate action between repeated sub-high temperature/cooling by water and sodium sulfate solution attack （TW-SA） were studied; meanwhile, the single sodium sulfate solution attack （SA） was also done as comparison. Micro-observations included the analysis of attack products by thermal analysis method and the determination of sulfate-ion content from surface to interior by chemical titrating method （modified barium sulfate gravimetric method）. Macro-observations mainly included the mechanical behaviors such as compressive strength, splitting strength. The experimental results indicate, in both cases, the main attack product is ettringite, only in the first layer of case SA some gypsum is checked; in case SA, the sulfate ions mainly concentrate in the surface layer, so the attack is relatively mild; but in case TW-SA, the repeated sub-high temperature/cooling by water promotes the sulfate ions diffusing inwards, which leads to obvious strength degradation.

关键词： concrete sulfate repeated sub-high temperature/cooling by water attack product sulfate-ion content strength

Slope Debris Flows in the Wenchuan Earthquake Area

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Journal of Mountain Science 2010年第3期7卷 226-233页

作者： LI Yanfu WANG Zhaoyin SHI Wenjing WANG Xuzhao state key laboratory of Hydroscienee and engineering Tsinghua University Beijing 100084 China beijing Institute of Geology for Mineral Resources Beijing 100012 China

Avalanches and landslides,induced by the Wenchuan Earthquake on May 12,2008,resulted in a lot of disaggregated,solid material on slopes that could be readily mobilized as source material for debris *** triggered numerous slope debris flows with great damage to highways and rivers over the subsequent two *** debris flows(as opposed to channelized debris flows) are defined as phenomena in which high-concentration mixtures of debris and water flow down slopes for short distances to highways and river *** on field investigations and measurements of 19 slope debris flows,their main characteristics and potential mitigation strategies were *** rainfall intensity is the main triggering *** rainfall intensities for simultaneous occurrence of single,several and numerous slope debris flow events were 20 mm/day,30mm/day,and 90 mm/day,*** investigations also revealed that slope debris flows consist of high concentrations of cobbles,boulders and *** are two-phase debris *** liquid phase plays the role of lubrication instead of transporting *** particles collide with each other and consume a lot of *** velocities of slope debris flows are very low,and their transport distances are only several tens of *** debris flows may be controlled by construction of drainage systems and by reforestation.

关键词： Slope debris flow rainfall intensity Wenchuan Earthquake landslide avalanche