Abstract: Theoretical analysis shows that the fine material transported as wash load is not only determined by flow intensity and particle size, but also strongly influenced by its concentration. It is demonstrated in this paper that rivers have a maximum transport capacity for fine material at a certain flow intensity, under which fine material can keep its fraction in bed load composition as zero. Otherwise, it behaves as bed material load. A new criterion of differentiation for wash load and bed material load is also proposed based on the theory of this paper.
Key words: wash load; maximum transport capacity; lift force; concentration gradient.
ZHONG De-yu,
WANG Shi-qiang, WANG Guang-qian
(Tsinghua University)
Abstract: The experimental result on wash load transport is reported in this paper. It shows that not only the grain size and flow intensity, but also the concentration of fine material plays important role on its mutual transformation between wash load and bed material load. The experiment demonstrates that there exists a maximum trasport capacity of stream for wash load under which fine material keeps its fraction in bed as zero and plays no part in river evolution process. Based on the theory established in Part Ⅰ of this paper, formulas for stream's maximum transport capacity of stream wash load and criterion for distinguishing wash load from bed material load are proposed. Comparison between the calculation result of the formula and the field data shows that the agreement is satisfactory.
Key words: wash load; maximum transport capacity; distinction criterion.
ZHU Da-yong1,
QIAN Qi-hu2, JIANG Hong-dao1
(1.Hohai University;2.PLA University of Technology)
Abstract: By extending and promoting the critical slip field method for slope analysis, passive critical slip fields in retaining structures are numerically computed along with passive earth pressure. The limit equilibrium equations are established with inter-slice force function introduced. The scheme for solving such equations and numerical technique for simulation critical slip field are presented. A monographic chart for determination of passive earth pressure is given.
Key words: retaining structure; earth pressure; critical slip field; passive critical slip field.
WANG Dang
xian,WANG Hao,MA Jing
(1.China Institute of Water Resources and Hydropower Research)
Key words: water resources;regional development;supporting capacity
DONG Xing lin1,GUO
Jun1,XIAO Bai yun2,ZHOU Zhong2
(1.China Institute of Water Conservancy and Hydroelectric Power Research；
2.Chengdu hydroelectric Investigation & Design institute)
Abstract: Based on the theory of free vortex and momentum equation the calculation formulas for discharge capacity,velocity and pressure distributions of vortex drop spillway are deduced.The design principles are verified in hydraulic model tests.
Key words: vortex drop spillway;vortex momentum torque;annular hydraulic jump
QIU Jin wei1,LI
Na1,CHENG Xiao tao1,XIA Xiang ao2
(1.China Institute of Water Resources and Hydropower Research；2.Meteorological Institute of Tianjin)
Abstract: A simulation system for heavy rainfalls in Tianjin City,including a numerical model system and an information system,is developed.The numerical model for heavy rainfall simulation,based on the theory of 2-D unsteady flow,is able to consider the variation of topography in urbanized area as well as the features of buildings.It can directly simulate the flooding in the urban area according to the rainfall information and realize the combination simulation of flooding on the ground and in drainage system.
Key words: Tianjin City;heavy rainfall; simulation model;drainage system;information management system
WANG
Wen-sheng,YUAN Peng,DING Jing
(Sichuan University)
Abstract: Signal composed of different frequencies can be decomposed into a series of signal by wavelet analysis.Based on the principle of decomposition and reconstruction of wavelet,the daily flow series are decomposed into sub-series with different scale.The wavelet coefficients and scale coefficients are stochastically reconstructed according to the main periods illustrated by the observed data.Thereby different daily flow graphs can be obtained through reconstructing signal curves with appropriate mode.When wavelet function and scale function are determined the parameters estimation is not necessary in the process of decomposition and reconstruction.At the same time no pre-analysis or assumption is needed.The stochastic simulation of daily flow at Ping-Shan hydrological station shows that wavelet analysis is feasible.
Key words: wavelet analysis; decomposition; reconstruction; stochastic simulation; verification of model
LEI Ting-wu1,
Mark A Nearing2
(1.Institute of Soil and Water Conservation,Yangling Shaanxi;2.USDA-ARS National Soil
Erosion
Research Institute,Purdue University,Lafayette)
Abstract: A series of flume experiments were conducted to understand shallow water hydraulics,erosion in rills as well as morphological patterns of a rill as effected by rill bed slopes and inflow rates.The soil used was Cecil soil,a sandy loamy soil。Four flow rates:3.8,7.6,11.4and 15.2 l/min and 4 slopes:1%,3%,5% and 7% were adopted in the experiments.The velocities.rill widths and sediment concentrations at the outlet were recorded and analyzed with multivariable regression method as functions of slopes,inflow rate and/or their interactive terms.Rill widths changing along the rill with certain periodical patterns were visulally observed.A mathematical model was advanced to describe these changing patterns of rill width。Sampling length for transport capacity was determined with the analysis of both sediment yields and width patterns.
Key words: flume experiment; rill erosion; periodical pattern; sampling length; transport capacity
ZHANG Bo-yan,
CHEN Hou-quan, DU Xiu-li, ZHANG Yan-hong
(China Institute of Water Resources and Hydropower Research)
Abstract: The traditional rigid body equilibrium method is used to incorporate with finite element method in analyzing the abutment aseismic stability of high arch dam.The mesh nodes should be arranged at the surface of potential slipping body during FEM calculation.By Integrating the static and dynamic stresses at the nodes on the slipping surface the thrust force and seismic load acting on the body are deduced.Thereby,teh aseismic stability safety coefficient of the arch dam abutment can be determined by rigid body limit equilibrium method.
Key words: arch dam; abutment aseisic stability; rigid body limit equilibrium method; FEM
WANG Yuan1,
JIANG Pu1, ZHU Jun-gao1，KONG Cai-fen2
(1.Hohai University)
Abstract：On the basis of experimental research on strain-softening behavior of loose sand under undrained condition,the steady-state strength concept and a strain-softening model are proposed.The effective stress FEM is adopted to analyze the post-earthquake stability of the liquefaction expanding zone as well as the whole section of a typical dike including its foundation,in consideration of the redistribution of stress and pore-water pressure.The result shows that the proposed method is feasible for practical use.
Key words：steady state strength; stability;dike; post-earthquake analysis; liquefaction
DU Qiang1,WAN
Li2,HU Fu-sheng2
(1.China Institute of Water Resources and Hydropower research;2.China University of
Geoscience)
Abstract：The stochastic simulation is applied to analyze the reliability of numerical simulation of seepage flow field at dam site.The sequence indicator simulation approach is applied to simulate the hydraulic conductivity of the fractured rock and a model for describing the 3-D seepage flow field is established.One hundred realizations of groundwater table are generated and the groundwater are statistically analyzed.The result shows that the conditional simulation of hydraulic conductivity well expresses the seepage characteristics of the fractured rock in the vicinity of dam site and the stochastic simulation can use to analyze the reliability of the simulation results.
Key words：heterogeneity;conditional simulation;groundwater flow modeling;reliability
GAO Dan-ying1,
Brahim Benmokrane2
(1.Zhengzhou University of Technology;2.University of Sherbrooke)
Abstract：The bonding properties of fiber reinforced polymer(FRP) rebars in concrete are experimentally studied through direct pullout and beam tests.The effects of concrete compressive strength,embedded length reinforcement diameter as well as concrete cast depth on bonding properties are investigated.The mechanism of the stress transferred from FRP rebars to concrete is analyzed.Finally,the design guideline for calculating the anchorage length of FRP rebars is recommended.
Key words：FRP rebar; concrete; bonding strength; anchorage length
PENG Qin-ge, LIU
Xing-nian, CAO Shu-you
(Sichuan University)
Abstract: The Back Propagation (BP) model of artificial neural networks is applied to predict the annual average sediment concentration in a watershed。The area of tree felling, quantity of felled trees, quantity of rainfall and annual average runoff reflecting the vegetation and climate of the watershed are selected as the main factors to establish the annual average sediment concentration model for prediction. The result shows that the delay effects of tree felling area and quantity of felled tree on annual average sediment concentration are obvious. The BP model not only possesses high accuracy of fitness but also attains precise prediction as well.
Key words: artificial neural networks; BP model; watershed;annual average sediment concentration; prediction
ZHOU Jian-jun1,
LIN Bing-nan2, ZHANG Ren1
(1.Tsinghua University,China;2.China Institute of Water Resources and Hydropower Research)
Abstract: A diversion canal connecting the Yangtze and Han river to utilize the Three Gorges Project and Danjiangkuo Project jointly dispatching the flood in the Jingjiang inundated area is proposed. The 60km long canal can divert 8000～9000m3/s flood discharge from Yangtze River to the lower Han River, or in reverse, diverts the flood to Yangtze River if serious flood is happened to Han River. Thereby the flood disaster in Jingjiang inundated area can be greatly mitigated. The feasibility as well as the additional advantages in water resources and navigation development of the canal are discussed. Some negative affairs pending for further investigation are also pointed out.
Key words: flood diversion canal; Yangtze River; Han River; TGP; Danjiangkuo Project
WU Cong lin,
HUANG Jie sheng, SHEN Rong kai
(Wuhan University of Hydraulic and Electric Engineering)
Abstract：A numerical model for analyzing the heat and water flow in the SPAC system under transparent polyethylene mulch is studied. A system consists of four layers including atmosphere, canopy, mulch and soil is established in the model. Energy balance equations are derived for each layer. Soil heat and water flow are described by one dimensional equations in which the interaction between heat and water is considered through the coefficients. Newton Raphson and finite difference methods are used to solve these equation. The model is verified by comparing the simulated soil temperature and soil pressure head profiles with measured data. The result shows that the agreement is satisfactory.
Key words：transparent polyethylene mulch; SPAC system; evapotranspiration; heat and water flow