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Deformation reinforcement theory and its application to high arch dams

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Science china(Technological Sciences) 2008年第S2期51卷 32-47页

作者： YANG Qiang,LIU YaoRu,CHEN YingRu & ZHOU WeiYuan state key laboratory of Hydroscience and hydraulic engineering,tsinghua university,beijing 100084,china 1. state key laboratory of Hydroscience and hydraulic engineering Tsinghua University Beijing 100084 China

In this paper,the deformation reinforcement theory(DRT) proposed by the authors is elaborated with a new definition of instability that an elasto-plastic structure is not stable if it cannot satisfy simultaneously equilibrium condition,kinematical admissibility and constitutive equations under the prescribed *** from the definition,a proof is established to the principle of minimum plastic complementary energy for failured *** is revealed that the principle of mini-mum plastic complementary energy results in relaxed constitutive equations,especially,yield *** is demonstrated with case studies that many key issues in arch dam design,e.g.,global stability,dam-toe reinforcement,dam-toe cracking,dam-abut-ment reinforcement,can be well solved within the framework of the deformation reinforcement *** structural global stability can be described by the curve of the plastic complementary energy vs overloading *** unbalanced-forces obtained by elasto-plastic FEM can be used as the basis of analysis of global stability,dam-heel cracking,dam-toe anchorage and reinforcement of faults of high arch dams and their foundations.

关键词： high arch dams global stability reinforcement unbalanced force plastic complementary energy

state of the art:Mechanical behavior of soil-structure interface

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Progress in Natural Science:Materials International 2009年第10期19卷 1187-1196页

作者： Ga Zhang,Jianmin Zhang state key laboratory of Hydroscience and engineering,tsinghua university,beijing 100084,china [a]state key laboratory of Hydroscience and engineering Tsinghua University Beijing 100084 China

The monotonic and cyclic behavior of a soil-structure interface has a significant effect on the mechanical response of a soil-structure interaction ***,the behavior of the interface should be investigated with focusing on the individual characters different from other geomaterials.A brief introduction and critical review are presented on the state of the art of monotonic and cyclic behavior of soil- structure interface,including the test device and measurement techniques,fundamental rules and deformation mechanism,constitutive models and their applications in the numerical *** tendencies of the investigation on the interface are also predicted in this paper.

关键词： Interface Soil Mechanical behavior Test Constitutive model Numerical analysis

Analysis micro-mechanism of burrs formation in the case of nanometric cutting process using numerical simulation method

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Science china(Technological Sciences) 2007年第2期50卷 129-137页

作者： HAN XueSong & HU YuanZhong state key laboratory of Tribology, tsinghua university, beijing 100084, china 1. state key laboratory of Tribology Tsinghua University Beijing 100084 China

Burrs (exit failure), being one of the important factors influencing the final precision of workpiece, have been widely studied. Today, with the development of manufacturing technology, the depth of cut falls into the range of nanometer or subnanometer, there may be some different disciplines dominating the burrs generation process. Molecular dynamics (MD) emthod, which is different from continuous mechanics, plays an important role in describing microscopic world. Take the example of single crystal copper, this paper carries out MD analysis micro-mechanism of burrs generation process. The results show that the burrs geometry depends on the type of workpiece (ductile or brittle). The depth of cut is decreased in the case of positive burrs generation process while the depth of cut is increased in case of negative burrs generation process. keywords burr - molecular dynamics - micro-mechanism Supported by china Postdoctor Science Foundation (Grant No. 20060390458)

关键词： burr molecular dynamics micro-mechanism

Sediment pollution and its effect on fish through food chain in the Yangtze River

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International Journal of Sediment Research 2008年第4期23卷 338-347页

Suspended sediment adsorbs pollutants from flowing water in rivers and deposits onto the bed. However, the pollutants accumulated in the river bed sediment may affect the bio-community through food chain for a long period of time. To study the problem the concentration of heavy metals (Cr, Cd, Hg, Cu, Fe, Zn, Pb and As) in water, sediment, and fish/invertebrate were investigated in the middle and lower reaches of the Yangtze River during 2006-2007. The concentrations of heavy metals were 100-10,000 times higher in the sediment than in the water. Benthic invertebrates had relatively high concentrations of heavy metals in their tissues due to their proximity to contaminated sediments. Benthic invertivore fish had moderately high concentrations of heavy metals whereas phytoplanktivore fish, such as the silver carp, accumulated the lowest concentration of heavy metals. The concentrations of Cu, Zn, and Fe were higher than Hg, Pb, Cd, Cr, and As in the tissue samples. The concentration of heavy metals was lower in the river sediments than in the lake sediments. Conversely, the concentration of heavy metals was higher in river water than in lake water. While a pollution event into a water body is often transitory, the effects of the pollutants may be long-lived due to their tendency to be absorbed in the sediments and then released into the food chain. The heavy metals were concentrated in the following order: bottom material > demersal fish and benthic fauna > middle-lower layer fish > upper-middle layer fish > water.

关键词： Sediment pollution Heavy metal Fish Invertebrate Yangtze River

Simulation of dam breach development for emergency treatment of the Tangjiashan Quake Lake in china

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Science china(Technological Sciences) 2008年第S2期51卷 82-94页

作者： WANG GuangQian,LIU Fan,FU XuDong & LI TieJian state key laboratory of Hydroscience and engineering,tsinghua university,beijing 100084,china state key laboratory of Hydroscience and engineering Tsinghua University Beijing 100084 China

The Tangjiashan Quake Lake is the largest quake lake triggered by the 5.12 Wenchuan Earthquake that happened on May 12,2008 in china,posing high risk of catastrophic flash flood hazards to downstream human life and properties.A physics-based numerical simulation approach is proposed for real-time prediction of dam breach development of the Tangjiashan Quake Lake in the case of emergency *** erosion and lateral development of the dam breach are represented through accounting for the underlying physics including selective sediment transport and gravitational *** breach erosion model that involves few parameters enables quick calibration based on the monitored hydrological data in emergency analysis where fully geotechnical information about the barrier dam is not *** process of dam breach development is found to be nonlinear in cascades due to the combined effects of headcutting and bank *** agreement between the simulation results and the observed data shows the applicability of the present approach for emergency analysis of quake *** will arise in the situation where the soil composition of barrier dam is significantly *** of circular arc failure for cohesive soil and lateral seepage in bank slope will also enhance its applicability to complex situations.

关键词： quake lake earthquake dam breach simulation numerical model erosion collapse headcutting

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

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

hydraulic design and pre-whirl regulation law of inlet guide vane for centrifugal pump

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Science china(Technological Sciences) 2010年第8期53卷 2142-2151页

作者： TAN Lei ,CAO ShuLiang&GUI ShaoBo state key laboratory of Hydroscience and engineering,Department of Thermal engineering,tsinghua university,beijing 100084,china 1. state key laboratory of Hydroscience and engineering Department of Thermal Engineering Tsinghua University Beijing 100084 China

A new hydraulic design method of three-dimensional guide vane for centrifugal pump is proposed on the assumption that the fluid at the outlet of guide vane satisfies the uniform velocity moment *** geometry of blade is controlled by the distributed rule of blade angles along the meridional streamline which is described by a fourth-order *** results demonstrate that the designed guide vane can overcome the drawback of two-dimensional guide vane,enlarge the high efficiency scope and improve the hydraulic performance of centrifugal pump on the off-design operation *** comparison with the performance of the centrifugal pump without inlet guide vane,the peak value of efficiency can be enhanced by 2.13% after the three-dimensional guide vane was being *** three-dimensional entire flow field of the centrifugal pump with inlet guide vane is simulated,and the basic principle and mechanism of inlet guide vane pre-whirl regulation are *** validity of design method has been proved.

关键词： centrifugal pump inlet guide vane pre-whirl regulation hydraulic design method experiment numerical simulation

PRINCIPLES OF RIVER TRAINING AND MANAGEMENT

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International Journal of Sediment Research 2007年第4期22卷 247-262页

作者： Zhaoyin WANG1, Shimin TIAN2, Yujun YI3, and Guoan YU4 1 Prof., state key laboratory of Hydroscience and engineering, tsinghua university, beijing, 100084, china 2 Ph. D., china Institute of Water Resources and Hydro-Power Research, beijing 100044, china. 3 Ph. D., state key laboratory of Hydroscience and engineering, tsinghua university, beijing, 100084, china 4 Ph. D., state key laboratory of Hydroscience and engineering, tsinghua university, beijing, 100084, china tsinghua Univ State Key Lab Hydrosci & Engn Beijing 100084 Peoples R China china Inst Water Resources & Hydropower Res Beijing 100044 Peoples R China

River regulation and river training have been performed for various purposes and negative effects have been shown in numerous cases. In some cases the negative effects are so serious that humans have to consider to "renaturalize" the regulated rivers. Only by using the strategy of integrated river management the diverse river uses and natural fluvial processes and ecological systems may be harmonized. Based on analysis of case studies and data collected from literatures this paper presents the concept of integrated river management and four principles of river training. The integrated river management comprises: 1) taking the watershed, upper stream basin including the tributaries, middle and lower reaches and the estuary as an integrated entity in the planning, design and management; and 2) mitigating or controlling the negative impacts on hydrology, erosion and sedimentation, fluvial processes, land use and river use, environment and ecology while in achieving economic benefit from water resources development, flood safety management and hydropower exploitation. River training and management should be in accordance with the four principles: 1) extending the duration of river water flowing on the continent, which may be achieved by extending the river course or reducing the flow velocity; 2) controlling various patterns of erosions and reducing the sediment transportation in the rivers; 3) increasing the diversity of habitat and enhancing the connectivity between the river and riparian waters; and 4) restoring natural landscapes.

关键词： River training Integrated river management Sediment Erosion control Ecological and landscape restoration