XU Jiong-xin
(Institute of Geographical Sciences and Natural Resources Research, CAS)
Abstract: In the history of China, two historic turns took place in the lower Yellow River. The first was the construction of artificial levee beginning from the middle Warring States Period thereby making the river suspended over the land. The second was beginning from 1990s because of excess exploitation of water resources leading to the changing of the river into a man-induced seasonal river or shrinking river. This paper deals with the analysis of the cause, process and the environmental impact of the second turn and aims at the resolution of the severe problems we are facing.
Key words: lower Yellow River; historic turn; river evolution; flood protection; geographical environment
Application of statistics of extremes of flood hazard risk evaluation
FU Xiang,WANG Li ping,JI
Chang ming
(Wuhan University)
Abstract: Based on the statistics of extremes,this paper studies the applicability of extremes in calculating hazard risk of flood damage.According to the limited information of extreme event the extremes risk function can be established to evaluate the expected value of flood damage,which is used to descibe the potential risk tendency of flood damage.The feasibility of the proposed method is verified by case study.
Key words: statistics of extremes;flood damage;risk evaluation
Review of studies on the hydrodynamic pressure and its effects on the seismic response of dams
DU Xiuli1 WANG
Jinting2
(1.Beijing Polytechnic
University;2.China Institute of Water Resources and Hydopower Research)
Abstract: A review of the development in the study of hydraulic dynamic pressure acting on dams during earthquake and its effects on seismic response of dam is given in detail.The study in this aspect was initiated in 1933 since the creative work of Westerguaad.In the early stage,some simplified models,for example rigid dam impounded water rigid foundation model,was used,because of the limittion of calculation tools.Now,by using computer,many numerical methods have been widely applied and the models for simulation are getting much more perfect,in which the interaction between dam and impounded water,the effects of flexible foundation,compressibility of water,sedimentaion as well as the non linearity of response are being considered.
Key words: earthquake;hydrodynamic pressre;review
Refraction-diffraction combined numerical model for random wave in unsteady non-uniform current
ZHU Zhi-xia1, HAN
Qi-wei1, BAI Yu-chuan2
(1.China Institute of Water Resources
and Hydropower Research;2.Tianjin University)
Abstract: Based on the mild slope equation considering the influence of current and according to the wave motion accumulation principle, a refraction-diffraction combined numerical model for random wave in tidal unsteady non-uniform current, appropriate to the condition of mild topography in large scale, is derived. The model is applied to the numerical calculations of random wave propagation on a seabed with semi-ellipsis slant slope and in the western zone of the Bohai gulf. Satisfactory results are obtained.
Key words: mild slope equation; random wave; tidal current; refraction-diffraction combined numerical model.
Performance prodiction and viscous flow analysis for Francis turbulence runner
GAO Zhong-xin, ZHOU
Xian-jin,ZHANG Shi-xiong,TANG Shu
(China Institute of Water Resources and Hydropower Research)
Abstract: A 3-D computational algorithm based on time average Navier-Stokes equations is proposed to predict the performance of a Francis runner, the governing equations are solved using a finite volume technique in a general curvilinear co-ordinate system. The standard k e turbulence model is applied to estimate the Reynolds stress.Numerical calculations are conducted for 4 operating conditions.Based on the calculated results of flow field,the efficiencies corresponding to these operating conditions are obtained.The performance predicted is in good agreement with model test.
Key words: Francis runner;viscous flow£»performance;predict;numerical analysis;k e turbulence model
Discussion on some problems in design of high pressure tunnel for hydro projects
HOU Jing1,HU Min
yun2
(1.East China Investigation and Design Institute;2.Zhejiang University of Technology)
Abstract: At present,the novway rwle and the minimal ground stress rule is adopted in the design of high pressure tunnel for hydro projects in China.Surface force theory and physical force theory are being applied in the calculation.However,the surface force theory fails to reflect the actual working conditions of the tunnel and the physical force theory takes no considerfation of the impact of high pressure consolidation grouting.According to the comparison of the calculation results and combining with the engineering practice,the application conditions of surface force theory and physical force theory are discussed.It is found that the physical force theory is suitable for the case when water head is over 150m.It indicates that the water pressure is mainly supported by the surrounding rock and high pressure consolidation grouting is very important for tunnel design.For intact surrounding rock with grade ¢ò or ¢ó,the rational grouting depth is recommended to be 0.75 times of the tunnel diameter.
Key words: high pressure tunnel;hydro project;surface force theory;physical force theory;consolidation grouting
Law of grouting penetrating through fracture network of rock mass
YANG Mi-jia1, HE Yong-nian2, CHEN Ming-xiong3
(1.Hohai University; 2.China University of Mining and Technology;3.College of Civil
Engineering)
Abstract: Based on the simulation of fracture structure,a new seepage model for non-Newton fluid in fracture network is developed.The approach for determining the parameters of grouting is proposed.Furthermore,the coupling of seepage and stress in the process of grouting as well as the effect of the coupling to the procedure of grouting are investigated.
Key words: fracture simulation; non-Newton fluid; seepage; stress; grouting parameters
The cause and prevention of cracking in high strength concrete of Xiaolangdi Project's outlet works
LIAO Bo
(Xiaolangdi Engineering Consulting Company)
Abstract: The cause of cracking in C70 silica fume concrete of outlet works in the Xiaolongdi Project is investigated.It is concluded that the cracking in early stage is mainly related to the temperature difference due to cement hydration heat and moisture difference due to drying.The cracking in later stage is due to the foundation temperature difference.The cracking can be effectively prevented if the fly ash is 20-40%,the temperature of the concrete is carefully controlled and the length of placement block is shortened.The epoxy resin injection and extra fineness cement grouting are adopted for cracking remedy and is proved to be very effective.
Key words: high strength concrete; cracking; epoxy resin injection; extra fineness cement grouting
Optimal operation of cascade reservoirs in upper reaches of Yellow River for preventing ice jam
LI Hui an1,HUANG
Qiang2,SHEN Jin2
(1.Irrigation Bureau,Institute of Hydraulic
research,YRCC;2.Xi'an University of Technology)
Abstract: The relation between the storage of Liujiaxia Reservoir ready for ice jam prevention and the power output of the cascade hydroelectric power stations is analyzed using system analysis method.The principle and approach for determination of storage and optimal operation of cascade power stations are proposed and a self optimization simulation model is established.The validity of the model is verified by the observation data.
Key words: cascade reservoirs;upper reaches of Yellow River;storage;optimal operation;ice jam prevention;simulation
The mechanism of corroded expansion force of reinforced concrete members
JIN Wei-liang, ZHAO Yu-xi,
YAN Fei
(Zhejiang University)
Abstract: In this paper,the formulas of corroded expansion expansion force(CEF) are established based on mechanics of elasticity.Some factors related to CEF are discussed¡£It is concluded that:the corrosion rate of steel bars is the most important factor that affecting the expansion fore;the concrete grade has nothing to do with the CEF but it affects the ultimate force during cracking.With the increaxse of the thickness of protective covering,the CEF increases slightly;whereas,with the increase of the bar diameter,the CEF decreases.The influence of abr diameter is stronger than the thickness of concrete protective covering layer.
Key words: reinforced concrete; reinforcing bar corrosion; corrosion; corrosion expansion force; durability
The flow structure along the vertical line under the interaction of current and wave
SUN Hong,HAN Guang, TAO
Jian hua
(Tianjin University)
Abstract£ºThe effect of wave on vertical distribution of horizontal flow velocity under the interaction of current flow and wave is studied. The current eddy viscosity model is applied to close Navier Stokes equations. A model is developed to predict the velocity distribution. The results from this model are in good agreement with the experimental data.
Key words£ºcurrent and wave combined flow£»Navier Stokes equations; eddy viscosity model; current velocity distribution.
Influence of reservoir operation on deposition in Wanan Hydro project
LIU Chen1, WAN Jian guo2
(1.Tianjin Research Institute of Water Transport Engineering;2.Design Institute for Water
Transport, Jiangsi Province)
Abstract£ºA 1-D sediment mathematical model for reservoir of Wanan Project is established. In the model a new mode of suspended transport of sedimentation for better describing the exchange mechanism between suspended load and bed material is proposed. The model is applied to study the influence of reservoir operation on deposition, water level variation during flood season as well as the changes of water depth for transport in dry season.
Key words£ºoperation; reservoir; deposition; flood control; transportation.
On sediment abrasion of deep level outlet in the Three Gorges Project
SUN Shuang-ke1£¬ ZHOU Sheng1, SHI Qi-sui2
(1.China Institute of Water Resources and Hydropower Research)
Abstract: Based on the experience accumulated and observation data in Liujiaxia Hydro project,the quantitative forecast of the sediment abrasion in deep level outlet of the Three Gorges Project is investigated. Measures for mitigation are also suggested.
Key words: Three Gorges Project£»deep level outlet; sediment abrasion; forecast
The structural strength and shear strength of unsaturated loess
DANG Jin-qian£¬LI Jing
(Northwest Science and Technology University of Agriculture and Forestry)
Abstract: The constitution and source of structural strength for unsaturated loess is analyzed. The method to determine the structural strength is proposed and the variation law of strength is studied.It is shown that the structural strength of unsaturated loess can be measured by the strength lost due to destruction, the relationship between strength and initial water content is exponential and the strength is linearly related to unsettled cohesion. The concept of terminative water content is suggested and the calculation formula for shear strength of unsaturated loess is obtained based on the experimental data.
Key words: unsaturated loess; structural strength; shear strength£»water content
Direct optimal dispatch of large scale water supply system
LU Mou1, ZHANG Tu-qiao1,
ZHAO Hong-bin2
(1.Zhejiang University;2.Harbin Institute of Technology)
Abstract£ºThe direct optimal dispatch model and corresponding calculation algorithm for large scale water supply system are proposed.The objective function and constraint equations are deduced.The technique of constraint condition softening is adopted to meet the need of engineering application.The software for solving the mixed discrete variables is developed.The applications to several cities show that this method is feasible and practical.
Key words£ºwater supply system; dynamic model; direct optimization; operation schedule
Computation model for interaction of soil and geogrid under dynamic load
ZHANG Xing-qiang1, DENG
Wei-dong2, CHEN Wen-jin, YAN Shu-wang1
(1.Tianjin University; 2.Chongqing Highway Scientific Research Institute,Ministry of
Communication;3.CODEC)
Abstract£ºA 2-D plane strain finite element interface model for analyzing interaction of soil and geogrid under dynamic load is proposed.The behaviors of dynamic interaction between the transverse bars,the longitudinal ribs and soil is simulated by a system consisting of nonlinear spring,damper and mass in order to study the deformation properties of reinforced soil.The equivalent siffness and damping ratios can be determined form the test on shaking table¡£A program for conputing the dynamic response of reinforced soil is proposed and the FEM analysis results agree well with the observation data.It shows that the model and the program are feasible.
Key words£ºreinforced soil; soil-geogrid; dynamic interaction; deformation properties; interface model