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Detection of subcritical crack propagation for concrete dams

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Science china(Technological Sciences) 2009年第12期52卷 3654-3660页

作者： BAO TengFei1 ,2.YU Hong 1,2.1college of water Conservancy&{2. engineering,Hohai university,Nanjing 2.0098,china 2.ational engineering Research Center of water resources Efficient Utilization and engineering Safety,Nanjing 2.0098,china college of water Conservancy & {2. engineering Hohai University Nanjing 210098 China National engineering Research Center of water {2. Efficient Utilization and engineering Safety Nanjing 210098 China

Subcritical propagation of cracks is a warning sign of *** such propagation is detected at an early stage,timely maintenance measures can be taken to prevent the failure of *** detect the subcritical propagation of a crack,the crack needs to be monitored continuously in a long term, which is not realistic under certain ***,cracks in concrete dams can be monitored continuously by dam monitoring to offer possible detection for subcritical *** this paper, with measured crack openings from dam monitoring,a state equation for characterizing crack development is established based on the grey system *** relation between the stability of the equation and the subcritical crack propagation is investigated,then a criterion is proposed for detecting subcritical *** example demonstrates the validity of the criterion and its potential for practical application.

关键词： crack subcritical propagation criterion concrete

Development of distributed time-variant gain model for nonlinear hydrological systems

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Science china Earth Sciences 2005年第6期48卷 713-723页

作者： XIA Jun1, 2. WANG Gangsheng1, TAN Ge1, YE Aizhong2.& G. H. Huang3 1. Key Laboratory of water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural resources Research, Chinese Academy of Sciences, Beijing 100101, {2. 2. State Key Laboratory of water resources & hydropower engineering Sciences, wuhan university, wuhan 43.072. china 3. Faculty of engineering, university of Regina, 3737 Wascana Parkway, Regina, Sask., S4S 0A2. Canada Correspondence should be addressed to Xia Jun 1. Key Laboratory of water Cycle & Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing China 2. State Key Laboratory of water resources & {2. engineering Sciences Wuhan University 430072 Wuhan China 3. Faculty of engineering University of Regina 3737 Wascana Parkway S4S 0A2 Sask Regina Canada

In this paper, a rainfall-runoff modeling system is developed based on a nonlinear Volterra functional series and a hydrological conceptual modeling approach. Two models, i.e. the time-variant gain model (TVGM) and the distributed time-variant gain model (DTVGM) that are built on the platform of Digital Elevation Model (DEM), Remote Sensing (RS) and Unit Hydro-logical Process were proposed. The developed DTVGM model was applied to two cases in the Heihe River Basin that is located in the arid and semiarid region of northwestern china and the Chaobai River basin located in the semihumid region of northern china. The results indicate that, in addition to the classic dynamic differential approach to describe nonlinear processes in hy-drological systems, it is possible to study such complex processes through the proposed sys-tematic approach to identify prominent hydrological relations. The DTVGM, coupling the advan-tages of both nonlinear and distributed hydrological models, can simulate variant hydrological processes under different environment conditions. Satisfactory results were obtained in fore-casting the time-space variations of hydrological processes and the relationships between land use/cover change and surface runoff variation.

关键词： hydrological process, nonlinearity, time-variant gain model, distributed hydrological model.

Experiments on Development of Channel Pattern in the Process of River Reformation

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四川大学学报（工程科学版） 2005年第S1期37卷 128-132页

作者： ZHANG Junyong CHEN Li LIU Yucheng DING Zhiliang(State Key Lab.of water resources and {2. Eng.Sci.,wuhan Univ.,wuhan 43.072.china) Lab. of water resources and {2. Eng. Sci. Wuhan Univ. Wuhan 430072 China

The changing of flow conditions caused by construction of hydro-projects will result in river's refor- mation and development of channel *** this paper,the development of channel pattern in the process of reformation is studied by means of flume *** of slope,grain size,angle-of-inflow,dis- charge and discharge process are comprehensively analyzed according to the experimental *** was found that the channel would be widened as the river slope or discharge increased and grain s...

关键词： reformation process channel pattern angle-of-inflow discharge process

Assessment model of dam operation risk based on monitoring data

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Science china(Technological Sciences) 2007年第z1期50卷 144-152页

作者： WU ZhongRu1,2., SU HuaiZhi1,2.& GUO HaiQing1 1 college of water Conservancy and {2. engineering, Hohai university, Nanjing 2.0098, china 2.National engineering Research Center of water resources Efficient Utilization and engineering Safety, Nanjing 2.0098, china 1. college of water Conservancy and {2. engineering Hohai University Nanjing 210098 China 2. National engineering Research Center of water {2. Efficient Utilization and engineering Safety Nanjing 210098 China

Although the dams produce remarkable social and economic benefits, the threat made by unsafe dams to the life and property of people who live in the lower river area is un-negligible. Based on the monitoring data which reflect the safety condition of dams, the risk degree concept is proposed and the analysis system and model for evaluating risk degree (rate) are established in this paper by combining the reliability theory and field monitoring data. The analysis method for risk degree is presented based on Bayesian approach. A five-grade risk degree system for dam operation risk and corresponding risk degree is put forward according to the safety condition of dams. The operation risks of four cascade dams on some river are analyzed by the model and approach presented here and the result is adopted by the owner.

关键词： dam monitoring data operation risk degree analysis model

THE ALGORITHMS AND APPLICATIONS FOR DETERMINING PERMEABILITY COEFFICIENTS BY PULSE SPECTRUM TECHNIQUE

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Journal of Hydrodynamics 2002年第2期14卷 112-115页

作者： Wang Ling-ling college of water Conservancy and {2. engineering, Hohai university, Nanjing 2.0098, china college of water Conservancy and {2. engineering Hohai University Nanjing 210098 China

The determination of inhomogeneous permeability coefficient was studied as a parameter-control inverse problem for parabolic-type equation in this paper. By virtue of PST, the solution of the inverse problem is converted into an iteration procedure of solving a direct problem and solving a Fredholm integral equation of the first kind. Besides, Tikhonov normalization method is introduced to treat the uncertainty caused by the integral equation. Thus an algorithm for determining inhomogeneous permeability coefficient has been formulated and implemented. Numerical results show: (1) The algorithm presented in the paper is suitable to strongly inhomogeneous seepagel; (2. The additional information needed for solution is merely the seepage velocity on partical boundary, so that drill works can be reduced remarkably; (3) The algorithm is applicable to determining inhomogeneous transmission coefficients in groundwater engineering or other engineering.

关键词： inverse problem Pulse Spectrum Technique (PST) permeability coefficient parameter identification

A 2.D HYDRODYNAMIC MODEL FOR THE RIVER,LAKE AND NETWORK SYSTEM IN THE JINGJIANG REACH ON THE UNSTRUCTURED QUADRANGLES

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Journal of Hydrodynamics 2010年第3期22卷 419-429页

作者： ZHANG Xi-bing HU De-chao WANG Min State Key Laboratory of water resources and {2. engineering Science Wuhan University Wuhan430072 China Yangtze River Scientific Research Institute Wuhan 430010 China State Key Laboratory of Hydroscience and engineering Tsinghua University Beijing 100084 China

The main river, the Dongting Lake and river networks in the Jingjiang reach of the Yangtze River constitute a complex water system, for which a full 2.D hydrodynamic model is established instead of the traditional 1-D or compound models for simulation of such complex systems, based on the latest developments of computer technologies and numerical methods. To better handle irregular boundaries and keep the computation cost well in a reasonable limit, unstructured grids of moderate scale are used. In addition, a dynamic boundary tracking method is proposed to simulate variable flow domains at different floods, especially, when the moderate scale gird can not describe flows in narrow river-network channels at low water levels. The t9 semi-implicit method and the Eulerian-Lagrangian Method （ELM） are adopted, which make the model unconditionally stable with respect to the gravity wave speed and Courant number restrictions. Properties and efficiency of the model are discussed, and it is concluded that the new model is robust and efficient enough for the simulation of a big, complex water system. Validation tests show that the simulation results agree well with field data. It takes about 0.96 h to complete the computation of a 76 d flood, which indicates that the model is efficient enough for engineering applications.

关键词： 2.D numerical model river network unstructured grid semi-implicit Eulerian-Lagrangian Method (ELM) boundarytracking

Field experiments on greenhouse gas emissions and nitrogen and phosphorus losses from rice paddy with efficient irrigation and drainage management

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Science china(Technological Sciences) 2011年第6期54卷 1581-1587页

作者： PENG ShiZhang1,2.YANG ShiHong1,2.XU JunZeng1,2.& GAO HuanZhi1,2.1State Key Laboratory of Hydrology-water resources and Hydraulic {2.,Hohai university,Nanjing 2.0098,china 2.5} of water Conservancy and hydropower {2.,Hohai university,Nanjing 2.0098,china 1. State Key Laboratory of Hydrology-water resources and Hydraulic {2. Hohai University Nanjing 210098 China2. College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

Greenhouse gas emissions,nitrogen and phosphorous losses through ammonia volatilization,leaching and surface drainage from rice paddy under efficient irrigation and drainage were analyzed based on field experimental data in order to reveal the eco-environmental impacts of efficient irrigation and drainage on rice *** results showed that total methane emission from rice paddy under the controlled irrigation was reduced by more than 80% and total nitrous oxide emission increased by 15.9% compared with flooding *** comprehensive global warming potentials(GWP) of methane and nitrous oxide were 62.2. gCO2.m-2.for rice paddy under the controlled irrigation,reduced by 68.0% compared with flooding *** to large reduction in seepage and surface drainages,nitrogen and phosphorous losses through leaching were reduced by 40.1% and 54.8%,nitrogen and phosphorous losses through surface drainage were reduced by 53.9% and 51.6% from rice paddy under efficient irrigation and drainage compared with traditional irrigation and *** loss through ammonia volatilization was reduced by 14.0%.Efficient irrigation and drainage management is helpful to mitigate greenhouse gases emission,nitrogen and phosphorus losses and their pollution on groundwater and surface water.

关键词： efficient irrigation and drainage nitrogen and phosphorus greenhouse gas ammonia volatilization paddy field

C-S-H Cluster Microstructure and Bonding Force Investigation base on AFM Technology

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Journal of wuhan university of Technology(Materials Science) 2010年第4期25卷 592-595页

作者：张博何真 State Key Laboratory of water resources and {2. engineering Science Wuhan University

AFM （atomic force microscopy） technology was applied on C-S-H （calcium silicate hydrate phase） microstructure investigation. The topographies of hydrated C3S （Tricalcium silicate） samples were firstly acquired with AFM. Accordingly, C-S-H can be identified according its pattern. Then the hydrated pssortland cement samples at different curing time were scanned with AFM. The topographies and force displacement curve were acquired and its characters at different days were summarized and analyzed. These results are very meaningful for C-S-H microstructure further investigation and cement-base material macro scale properties improvement.

关键词： C-S-H atomic force microscopy microstructure tricalcium silicate

A new method of estimating the equivalent elastic modulus of RCCD

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Science china(Technological Sciences) 2007年第z1期50卷 136-143页

作者： GU ChongShi1,2., WU Yuan1, SU HuaiZhi1,2.& TANG LiHui1 1 college of water Conservancy and {2. engineering, Hohai university, Nanjing 2.0098, china 2.National engineering Research Center of water resources Efficient Utilization and engineering Safety, Nanjing 2.0098, china college of water Conservancy and {2. engineering Hohai University Nanjing 210098 China National engineering Research Center of water {2. Efficient Utilization and engineering Safety Nanjing 210098 China

Based on the composite material mechanic theory, the analysis method for the equivalent elastic moduli which are parallel and vertical to the construction interface of RCCD is studied in this paper. The differences between the equivalent elastic moduli which are vertical to the construction interface of RCCD gotten from different methods are discussed in detail. The variation range of the equivalent elastic modulus which is vertical to the construction interface of RCCD is studied based on the principle of minimum complementary energy and the principle of minimum potential energy. The effect of the related influential factors on the equivalent elastic modulus is analyzed. The estimation formula of the equivalent modulus which is vertical to the construction interface of RCCD is proposed. The feasibility of the approach proposed in this paper is analyzed through an example.

关键词： RCCD equivalent elastic modulus variation range estimation method