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Temporal and spatial distribution of dam failure events in china

International Journal of Sediment Research 2008年第4期23卷 398-405页

作者： X.Y.HE 1,Z.Y.WANG 2,and J.C.HUANG 31 Senior Engineer,Department of water Hazard Research,china Institute of water resources and hydropower Research,Beijing 100038,china2 Prof.,State Key Laboratory of Hydroscience and engineering,Tsinghua university,Beijing 100084,china 3 Prof.,Department of water Hazard Research,china Institute of water resources and hydropower Research,Beijing 100038,china [a]Senior Engineer Department of water Hazard Research china Institute of water resources and hydropower Research Beijing 100038 china [b]Prof. State Key Laboratory of Hydroscience and engineering Tsinghua university Beijing 100084 china [c]Prof. Department of water Hazard Research china Institute of water resources and hydropower Research Beijing 100038 china

Reservoirs play a vital role in economic development and flood control. Nevertheless, both human and natural factors may lead to dam failures with catastrophic consequences. Analyzing the data of dam failure events from 1954 to 2003 and using the method of energy spectrum analysis, this paper studies the periodicity of dam failures. The rate of failure of different dam ages is analyzed. The climate is the main factor affecting the rate of dam failure. Climate diagrams are used to analyze the spatial distribution of dam failure events in china. High rate of dam failure occurs with 25-year and 12.5-year periods. The distribution of the percentage of dam failure shows an L-shape as a function of service age. The first 5 years of operation is known as the "infant period", during which, the probability of dam failure is much higher than during any other periods. The failure rate in areas near or north to the 400 mm annual isopluvial line is notably higher than other areas. In areas with high temperature difference among seasons have a high annual average dam failure rate.

关键词： Dam failure Temporal and spatial distribution Service age Climate diagram

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Characterization of Pozzolanic Reaction and Its Effect on the C-S-H Gel in Fly Ash-cement Paste

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Journal of Wuhan university of Technology(Materials Science) 2011年第2期26卷 320-325页

作者：王磊何真 State Key Laboratory of water resources and hydropower engineering Science Wuhan University

High resolution solid-state 29Si MAS NMR,combined with XRD,SEM and FTIR were used to characterize the pozzolanic activity of FA,type of main pozzolanic reaction products,and the effect of pozzolanic reaction on the C-S-H microstructure in fly ash-cement （FC） *** experimental results indicate that in the hydrated FC paste with 30% dosage of FA at 3 d,FA partially participated in the pozzolanic reaction,while,at 120 d,FA largely *** the hydration of FC paste at laboratory temperature,the pozzolanic reaction products are C-S-H gel rather than zeolitic ***,after the covalent bonds of Si-O-Si,Si-O-Al and Al-O-Al in the structure of FA are broken,monosilicates Si-OH and Al-OH groups form,these chemical species can connect C-S-H dimers,thus producing more Al-free C-S-H and aluminous C-S-H than in the plain cement *** increased content of Al for Si substitution in the bridging tetrahedra of C-S-H may decrease the stability of C-S-H,which results in a rather obvious loss in the mechanical strength of hardened FC paste.

关键词： NMR C-S-H microstructure dimer polymerization

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Preparation and performances of bulk porous Al foams impregnated with phase-change-materials for thermal storage

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Progress in Natural Science:Materials International 2012年第5期22卷 440-444页

作者： Jinghua Jiang a,b,Yingying Zhu b,Aibin Ma a,b,Donghui Yang b,c,Fumin Lu b,Jianqing Chen b,Jun Shi b,Dan Song a,b a National engineering Research Center of water resources Efficient Utilization and engineering Safety,hohai university,nanjing 2.0098,china b college of Mechanics and Materials,hohai university,nanjing 2.0098,china c Department of Mechanical and Aerospace engineering,North Carolina State university,Raleigh,NC 27695-7919,USA [a] National engineering Research Center of water resources Efficient Utilization and engineering Safety Hohai University Nanjing 210098 China [b] college of Mechanics and Materials Hohai University Nanjing 210098 China [c] Department of Mechanical and Aerospace engineering North Carolina State University Raleigh NC 27695-7919 USA

Shape-stabilized phase change materials(PCMs) exhibit desirable thermal storage properties and are used for energy conservation *** study is focused on the preparation and thermal-/dynamic-mechanical properties of the bulk porous Al foams impregnated with organic PCMs such as paraffins and stearic *** results indicated that the new shape-stabilized PCMs composites could be produced by a simple and eco-friendly constant-pressure impregnation *** filling fraction of PCMs was approximately more than 80% for the impregnated samples with vacuuming or without *** shape-stabilized PCMs/Al-foam composites exhibited considerable latent thermal storage potential for good interface,desirable phase-change temperature range and latent heat values(72.9kJ/kg for the paraffin/Al-foam composite and 66.7kJ/kg for the stearic acid/Al-foam composite).Moreover,the impregnation of PCMs improved the dynamic-compression yield strength,durability and resistance to oxidation of Al foams and made its ideal energy-saving materials.

关键词： Phase change materials Porous Al foams Composites Thermal storage Dynamic mechanical properties

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Variational iteration method for solving time-fractional diffusion equations in porous the medium

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Chinese Physics B 2012年第12期21卷 118-122页

作者：吴国成 Key Laboratory of Numerical Simulation of Sichuan Province Neijiang Normal UniversityNeijiang 641112China college of water resources and hydropower Sichuan UniversityChengdu 610065China

The variational iteration method is successfully extended to the case of solving fractional differential equations, and the Lagrange multiplier of the method is identified in a more accurate way. Some diffusion models with fractional derivatives are investigated analytically, and the results show the efficiency of the new Lagrange multiplier for fractional differential equations of arbitrary order.

关键词： time-fractional diffusion equation Captuo derivative Riemann-Liouville derivative,variational iteration method Laplace transform

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Simultaneous Recrystallization and Oxidation Behavior of Mn-Containing IF Steel

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Journal of Iron and Steel Research International 2012年第8期19卷 67-74页

作者： ZHANG Zuo-tai, ZHANG Ying-yi (Department of Energy and resources engineering, college of engineering, Peking university, Beijing 100871, china) Department of Energy and resources engineering College of Engineering Peking University Beijing 100871 China

The recrystallization and oxidation of a Mn-containing interstitial free (IF) steel were investigated simultaneously using confocal scanning laser microscope (CSLM) under controlled atmosphere of Ar 95% and H2 5% (in volume percent) at different temperatures. It was found that the grain boundary played a significant role in controlling recrystallization and oxidation in overall oxidation kinetics of the steel. The surface morphology was composed of two networks along the original and new grain boundaries respectively, which did not coexist. The grain boundary moved in different directions with different velocities during annealing process. The recrystallization processes were studied by CSLM motion video through observing the moving grain boundary to estimate the time for 50% recrystallization, and the activation energy for recrystallization was therefore calculated. The oxidation mechanism was discussed through comparison of the fluxes among mass transfer of water vapor, dissociation of water vapor and outward diffusion alloying elements. The results indicated that the oxidation was controlled by the mass transfer from the bulk gas to the surface, or dissociation rate, or outward diffusion of manganese, which depended on the temperature to form a grain boundary ridge or groove.

关键词： IF steel oxidation recrystallization grain boundary

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CHARACTERISTIC ANALYSIS OF THE PLUNGING OF TURBIDITY CURRENTS

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Journal of Hydrodynamics 2010年第2期22卷 274-282页

作者： AN Rui-dong LI Jia State key Laboratory of Hydraulics and Mountain River engineering Sichuan University Chengdu 610065China college of water Recourse and hydropower Sichuan University Chengdu 610065 China

Turbidity currents are flows driven by suspended sediment of flood-induced turbid river water with excess *** currents are often the governing factor in reservoir sedimentation by transporting fine materials over long distances and delivering the majority of deposition,which thus reduces the storage ***,the design and operation of a reservoir requires an accurate prediction of its occurrence condition and plunging position,which is the objective of the present *** article presents a verified algebraic slip mixture model including momentum,continuity and algebraic velocity expressions to simulate 2-D turbidity *** experiments in a multiphase flume were carried *** number,sediment concentration and densimetric Froude number were used as parameters in the occurrence condition *** plunging of turbidity currents may produce reflux and backflow due to the diving flow at the surface of the clear *** similar experimental results were also obtained by PIV measurements

关键词： turbidity current plunge suspend sediment algebraic slip mixture model densimetric Froude number

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A process-based model for sediment transport under various wave and current conditions

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International Journal of Sediment Research 2011年第4期26卷 498-512页

作者： Chi ZHANG,Jin-Hai ZHENG,Yi-Gang WANG, Meng-Tao ZHANG,Dong-Sheng JENG,and Ji-Sheng ZHANG 1 Dr.,State Key Laboratory of Hydrology-water resources and Hydraulic engineering,hohai university,1 Xikang Road,nanjing 2.0098,china, 2 Prof,Corresponding author,State Key Laboratory of Hydrology-water resources and Hydraulic engineering, hohai university,1 Xikang Road,nanjing 2.0098,china, 3 Prof.,4 Bachelor,6 Assoc.Prof.,college of Harbor,Coastal and Offshore engineering,hohai university,1 Xikang Road,nanjing 2.0098,china 5 Prof,Center for Marine Geotechnical engineering Research,Shanghai Jiao Tong university,Shanghai 200240, china Division of Civil engineering,university of Dundee,Dundee DD1 4HN,United Kingdom [a] Dr. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University 1 Xikang Road Nanjing 210098 China [b] Prof. Corresponding author State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University 1 Xikang Road Nanjing 210098 China [c] Prof. College of Harbor Coastal and Offshore Engineering Hohai University 1 Xikang Road Nanjing 210098 China [d] Bachelor College of Harbor Coastal and Offshore Engineering Hohai University 1 Xikang Road Nanjing 210098 China [e] Prof. Center for Marine Geotechnical Engineering Research Shanghai Jiao Tong University Shanghai 200240 China Division of Civil engineering University of Dundee Dundee DD1 4HN United Kingdom [f] Assoc. Prof. College of Harbor Coastal and Offshore Engineering Hohai University 1 Xikang Road Nanjing 210098 China

The purpose of this study is to investigate the capability of a newly developed process-based model for sediment transport under a wide variety of wave and current *** model is based on the first-order boundary layer equation and the sediment advection-diffusion *** particular,a modified low Reynolds number k-e model is coupled to provide the turbulence *** model verifications have been performed by simulating a number of laboratory experiments,covering a considerable range of hydrodynamic conditions such as sinusoidal waves,asymmetric waves and wave-current *** model provides satisfactory numerical results which agree well with the measured results,including the time-averaged/dependent sediment concentration profiles and sediment flux profiles,as well as the time series of concentration at given *** observed influences of wave orbital velocity amplitude,wave period and sediment grain size are correctly reproduced,indicating that the fundamental physical mechanisms of those processes are properly represented in the *** is revealed that the present model is capable of predicting sediment transport under a wide range of wave and current conditions,and can be used to further study the morphodynamic processes in real coastal regions.

关键词： Sediment transport Wave Current Numerical model

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Migration of Infiltrated NH_4 and NO_3 in a Soil and Groundwater System Simulated by a Soil Tank

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Pedosphere 2008年第5期18卷 628-637页

作者： WANG Chao WANG Pei-Fang State Key Laboratory of Hydrology- water resources and Hydraulic engineering Key Laboratory of Integrated Regulationand Resource Department on Shallow Lakes Ministry of Education Environmental Science and Engineering CollegeHohai University Nanjing 210098 （China）.

The infiltration of water contaminants into soil and groundwater systems can greatly affect the quality of groundwater. A laboratory-designed large soil tank with periodic and continuous infiltration models, respectively, was used to simulate the migration of the contaminants NH4 and NO3 in a soil and groundwater system, including unsaturated and saturated zones. The unsaturated soil zone had a significant effect on removing NH4 and NO3 infiltrated from the surface water. The patterns of breakthrough curves of NH4 and NO3 in the unsaturated zone were related to the infiltration time. A short infiltration time resulted in a single sharp peak in the breakthrough curve, while a long infiltration time led to a plateau curve. When NH4 and NO3 migrated from the unsaturated zone to the saturated zone, an interracial retardation was formed, resulting in an increased contaminant concentration on the interface. Under the influence of horizontal groundwater movement, the infiltrated contaminants formed a contamination-prone area downstream. As the contaminants migrated downstream, their concentrations were significantly reduced. Under the same infiltration concentration, the concentration of NO3 was greater than that of NH4 at every corresponding cross-section in the soil and groundwater tank, suggesting that the removal efficiency of NH4 was greater than that of NO3 in the soil and groundwater system.

关键词： breakthrough curve migration NH4 NO3 soil tank experiment

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Study on real working performance and overload safety factor of high arch dam

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Science china(Technological Sciences) 2008年第S2期51卷 48-59页

作者： ZHANG GuoXin,LIU Yi & ZHOU QiuJing Department of Structures and Materials,china Institute of water resources and hydropower Research,Beijing 100038,china 1. Department of Structures and Materials China Institute of Water Resources and Hydropower Research Beijing 100038 China

Considering the fact that high arch dams have problems such as complicated stress,high cost,and hazards after being damaged,this paper intends to study the effects of load,material strength,and safety analysis method on dam safety and working performance of arch *** this article,the effects of temperature,self weight exaction way and water loading on structure response are first discussed,and a more reasonable way of considering is then put *** taking into consideration the mechanical property of materials and comparing the effects of different yield criteria on overloading safety of high arch dams,this paper concludes that brittle characteristics of concrete should be fully considered when conducting safety assessment for high arch dams to avoid overestimating the bearing capacity of the *** comparing several typical projects,this paper works out a safety assessment system of multiple safety and relevant engineering analogical analysis methods,which is closer to the actual situation,and thus is able to assess the response of high arch dam structure in a more comprehensive way,elicit the safety coefficients in different situations,and provide a new way of considering the safety assessment of high arch dams.

关键词： high arch dam real working performance safety load strength safety assessment method

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Effects of landuse change on surface runoff and sediment yield at different watershed scales on the Loess Plateau

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International Journal of Sediment Research 2010年第3期25卷 283-293页

作者： ZHANG Xiaoming1, CAO Wenhong2, GUO Qingchao3, and WU Sihong41 Assoc. Prof. Dr., china Institute of water resources and hydropower Research, Beijing 100048, china, 2,3 Prof. Dr., china Institute of water resources and hydropower Research, Beijing 100048, china, 4 Dr., Department of Land and water resources engineering, Royal Institute of Technology, Stockholm, SE-100 44, Sweden [a] Assoc. Prof. Dr. China Institute of Water Resources hydropower Research Beijing 100048 China [b] Prof. Dr. China Institute of Water Resources hydropower Research Beijing 100048 China [c] Prof. Dr. China Institute of Water Resources hydropower Research Beijing 100048 China [d] Dr. Department of Land water resources engineering Royal Institute of Technology Stockholm SE-100 44 Sweden

Erosion and sediment yield from large and small watersheds exhibit different laws. Variations in surface runoff and sediment yield because of landuse change in four watersheds of different scales from 1 km2 to 73 km2 were analyzed. Due to reforestation and farmland terracing, surface runoff and sediment yield reduced by 20-100% and 10-100% respectively. Reductions in surface runoff were differed significantly under different precipitation regimes. For the large watershed (73 km2) landuse change had similar effects on surface runoff regardless of changing of precipitation. For the small watershed (1 km2) landuse change had fewer effects on surface runoff under high precipitation. The relative changes of sediment yield in the four watersheds under reforestation and farmland terracing decreased as precipitation increased from 350 mm to 650 mm, then increased as precipitation increased from 650 mm to 870 mm. Where initial forest coverage rate was below 45%, sediment yield decreased dramatically as forest coverage rate increased. watershed management with aiming at reducing both surface runoff and sediment yield should be conducted both on sloping surfaces and in channels in large watersheds.

关键词： Soil erosion Land use change Scale effect Surface runoff and sediment yield watershed Loess Plateau

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