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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 Engineering,hohai university,Nanjing 2.0098,china {2. of Water conservancy and hydropower Engineering,hohai university,Nanjing 2.0098,china State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing China College of Water conservancy and {2. Engineering Hohai University Nanjing 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

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Thermal Conductivity and Heat Transfer Coefficient of Concrete

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Journal of Wuhan university of Technology(Materials Science) 2011年第4期26卷 791-796页

作者：郭利霞 North china university of Water Resources and Electric Power

A very simple model for predicting thermal conductivity based on its definiensis was presented. The thermal conductivity obtained using the model provided a good coincidence to the investigations performed by other authors. The heat transfer coefficient was determined by inverse analysis using the temperature measurements. From experimental results, it is noted that heat transfer coefficient increases with the increase of wind velocity and relative humidity, a prediction equation on heat transfer coefficient about wind velocity and relative humidity is given.

关键词： thermal conductivity heat transfer coefficient relative humidity wind velocity

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Research on stability of the accumulated rock-soil body of reservoir bank under rainfall condition

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Science china(Technological Sciences) 2009年第9期52卷 2528-2535页

作者： GU ChongShi1,2.WU HaiZhen1,2.& SU HuaiZhi1,2.1 College of Water Resources and hydropower Engineering,{2.,Nanjing 2.0098,china 2.National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety,{2.,Nanjing 2.0098,china 3 Jiangxi Water conservancy Research Institute,Nanchang 33002.,china College of Water Resources and hydropower Engineering Hohai University Nanjing China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing China Jiangxi Water conservancy Research Institute Nanchang China

The shear strength parameters property of rock-soil aggregates in embankment slope of reservoir,that is,the relationship between cohesion and gravel content,between friction angle and gravel content,and the relationship between cohesion and water content,between friction angle and water content,is studied based on the direct shear test results,the shear strength change law of the rock-soil aggregates is given,and the unsaturated shear strength formulation of rock-soil aggregates that could consider suction and saturation degree influence is put forward in this paper,through which the sliding or failure physical mechanism of this type of slope under the condition of rainfall infiltration is studied. Also the 3D unsteady saturated-unsaturated seepage field and its FEM resolving mode are established based on the analysis of the slope rainfall infiltration process. Case study with this method indicates that the minimum safety factor of the accumulated rock-soil aggregates dose not arrive at the moment of rainfall cessation,but appears several hours after the rainfall cessation,this phenomenon is in accordance with the practical slope engineering's failure process and could explain appropriately the slope failure caused by rainfall infiltration. Research results in this paper have an important reference value for the research on stability of the accumulated rock-soil aggregates in embankment slope of reservoir,and can enrich the stability analysis method and relevant theory of reservoir embankment slope.

关键词： reservoir bank slope rock-soil aggregates rainfall infiltration saturated/unsaturated seepage

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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 China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing 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

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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 College of Water conservancy and {2. Engineering Hohai University Nanjing China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing 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

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Review on hidden trouble detection and health diagnosis of hydraulic concrete structures

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Science china(Technological Sciences) 2007年第Z1期50卷 34-50页

作者： WU ZhongRu1,2., LI Ji1, GU ChongShi1,2.& SU HuaiZhi1,2.1 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 China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing China

A large number of hydraulic concrete structures have hidden defects such as cracks, erosion, freeze and thaw, thermal fatigue, carbonization. These hidden defects seriously affect the strength, stability and durability of structures. These problems are studied mainly by single monitoring or diagnosis methods at present. The integration of multiple monitoring and diagnosis methods is not applied widely. Besides, the analysis theory on these problems is not developed very well. The systemic study on the aging mechanism of hydraulic concrete structures, time- variation model and health diagnosis is still not enough. The support for engineering practice is limited. Aimed at these major scientific and technological problems and combined with specific projects, study on detection of hidden defects and health diagnosis of hydraulic concrete structure has been carried out. This study includes the following content: field non-destructive examination of hidden defects of hydraulic concrete structures, seepage detection, the construction of in-situ sensing system, the combination of field detection and in-situ monitoring, the mechanism of crack, freeze and thaw, erosion and carbonization of hydraulic concrete structure, mechanism of combination aging; time-variation model of hydraulic concrete structure, theories and methods for health diagnosis of hydraulic concrete structures.

关键词： hydraulic concrete structure hidden trouble detection health diagnosis

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Numerical simulation of two-phase turbulent flow in hydraulic and hydropower engineering

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Science china(Technological Sciences) 2007年第Z1期50卷 79-89页

作者： DAI HuiChao1,2., WANG LingLing1, GAO JiZhang3, ZHANG XiaoDong3 & YANG ZhongHua2.1 College of Water conservancy and {2. Engineering, hohai university, Nanjing 2.0098, china 2.china Yangtze River Three Gorges Project Development Corporation, Yichang 443002. china 3 china Institute of Water Resources and {2. Research, Beijing 100044, china College of Water conservancy and {2. Engineering Hohai University Nanjing China china Yangtze River Three Gorges Project Development Corporation Yichang China china Institute of Water Resources and hydropower Research Beijing China

In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures, the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper. Furthermore the numerical method is proposed to treat bubbled flows. In addition, on the basis of air-water stratified twin flow model, the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface. Finally, the proposed model is used to calculate artificial aerated flows. The computed results coincide quite well with experimental results. This means that the proposed method can provide solid basis for practical engineering design.

关键词： high turbulence two-phase flow twin flow model aerated flow free surface

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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 China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing 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

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A general finite element model for numerical simulation of structure dynamics

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Science china(Physics,Mechanics & Astronomy) 2006年第4期49卷 440-450页

作者： WANG Fujun1, LI Yaojun1, Han K.2.& Feng Y.T.2.1. College of Water conservancy and Civil Engineering, {2. Agricultural university, Beijing 100083, {2. 2. Civil & Computational Engineering Centre, university of Wales Swansea, Swansea SA2.8PP, U.K. College of Water conservancy and Civil Engineering China Agricultural University Beijing China Civil & Computational Engineering Centre University of Wales Swansea Swansea UK

A finite element model used to simulate the dynamics with continuum and discontinuum is presented. This new approach is conducted by constructing the general contact model. The conventional discrete element is treated as a standard finite element with one node in this new method. The one-node element has the same features as other finite elements, such as element stress and strain. Thus, a general finite element model that is consistent with the existed finite element model is set up. This new model is simple in mathematical concept and is straightforward to be combined into the existing standard finite element code. Numerical example demonstrates that this new approach is more effective to perform the dynamic process analysis in which the interactions among a large number of discrete bodies and continuum objects are included.

关键词： finite element method, discrete element method, structure dynamics, numerical simulation.

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Hybrid method of limit equilibrium and finite element internal force for analysis of arch dam stability against sliding

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Science china(Technological Sciences) 2011年第4期54卷 793-798页

作者： BAO TengFei1,2.3,XU BaoSong1,2.3 & ZHENG XueQing1,2.3 1State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,hohai university,Nanjing 2.0098,china 2.ational Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety,Nanjing 2.0098,china 3College of Water conservancy and hydropower Engineering,hohai university,Nanjing 2.0098,china State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing China College of Water conservancy and {2. Engineering Hohai University Nanjing China

A hybrid method of limit equilibrium and finite element internal force for analysis of arch dam stability against sliding is *** finite element internal force method(FEIFM) is used to provide more accurate thrust forces acting on the faces of a slip body,and the limit equilibrium method(LEM) is employed to evaluate the factor of safety of the slip *** method presented can deal with a slip body with large amount of geometrically complex slip *** addition,compared with the traditional LEM,it can meet the balance condition of the forces in the slip *** example shows that the factor of safety obtained by the method presented agrees well with the theoretical solution.A practical example is also presented to demonstrate the application of the method in the stability analysis of an arch dam *** results from the examples show that the method is promising in analysis of arch dam stability against sliding.

关键词： arch dam stability against sliding limit equilibrium method finite element internal force method

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