Modeling of rill evolution on loess slope in terms of concept of self-organization
NI Jin-ren, ZHANG Jian, HAN Peng
(Peking University)
Abstract: Rill erosion plays a very important role in the study of slope erosion. Based on the review of methods widely used in the study of rill erosion, characteristics of slope evolution are analyzed and a model is developed based on the concept of self-organization. The model could be used for simulating rill evolution processes on loess slopes, in which the rainfall and micro-landform are corresponding to the disarranged input and the rills are corresponding to the regular output. The modeling results are in good agreement with experimental data. The splash erosion is not considered in the model, but the effect of the simulation and other controlling factors in the model are analyzed.
Key words: loess slope; rill evolution; self-organization; model
Optimization analysis of large-scale underground reinforced concrete branching conduit
XIAO Ming
(Wuhan University)
Abstract: Based on failure conditions of reinforced concrete and elastoplastic principle of rock energy dissipation, an optimization analysis method to assess best structure of large-scale underground reinforced concrete conduit is developed. The combined effect of surrounding rock and lining is considered. An automatic program to generate various 3-D finite element mesh of the branching conduit is introduced which can automatically judge and create 3-D FEM net when several control parameters of the structure are imported. The application of this method shows that it sufficiently responses the influence of geological condition, geological stress and parameters of the branching conduit structure. The method is convenient, flexible and high efficiency.
Key words: underground; branching conduit; 3-D FEM; optimized structure.
Water pollution synergetic control
LI Jia1,ZHANG Jian
gao2
(1.Sichuan University;2.Chongqing Universtiy)
Abstract: The 1-D mathematical model of water pollution synergetic control in river for single contamination is established.It is based on the classical cooperative game model.The basic concept of synergetic control is that the total discharged volume and concentration of every contamination source are restricted according to the impartial principle and the pollution level in the river section should be controlled not to exceed the standard designated by the government.
Key words: water pollution; synergetic control; cooperative game; environmental capacity
Calculation method of the soil water upword flux at the botton boundary of the root zone
LIU Yu1, CAI Lin-gen1,
R.M.Fernando2, L.S.Pereira2
(1.China Institute of Water Resources and Hydropower Research;2.Institute of Agronomy,
Technical University of Lisbon, Portugal)
Abstract: A 1-D soil water dynamic model-WAVE (Vanclooster et al 1994) is calibrated and validated by comparing the simulation results with the field experiment data.The model is used to simulate the upward flux at the bottom boundary of root zone in different conditions of groundwater depth and potential crop evapotranspiration.A semi-empirical relation between the capillary rise to the root zone and the water stored in the root zone is derived.This relation is used to improve the soil water balance model to better consider the groundwater contribution to be applied in the irrigation scheduling studies.
Key words: groundwater; capillary rise; calculation method; water balance
Market mechanism of water resources allocation and its efficiency
WANG Xian jia1,XIAO
Wen2
(1.Wuhan Universtiy;2.Water Resources Bureau of Shenzhen City)
Abstract: The mathematical models for centralized mechanism and market mechanism of water resources allocation are established respectively.The problems existing in centralized mechanism are analyzed in term of the ideas of information economics.The efficiency of the market mechanism is revealed by an equilibrium price system.The efficiency implies that in the equilibrium price system the market mechanism can realize the maximum whole benefit of the centralized mechanism.Meanwhile,the problems in market mechanism of water resources allocation are also pointed out.
Key words: water resources; centralized mechanism; market mechanism; equilibrium price system;efficiency
Experimental study and numerical model of gas-liquid two-phase flow in aeration tank
CHENG Wen,SONG Ce,ZHOU Xiao de
(Xi'an University of Technolgy)
Abstract: Aeration plays an important role in the treatment of activated sludge and the velocity of bubble rising in water is of critical effect upon aeration.Based on the experimental study, a K ¦Å mathematical model for gas liquid two phase turbulent flow is established.The calculated result is in good agreement with experimental data.
Key words: aeration tank;two phase turbulent flow;numerical model
Research on the criteria of combined comtrolling of surface and subsurface waterlogging
SHEN Rong-kai, WANG Xiu-gui,
ZHANG Yu-fang
(Wuhan University)
Abstract: During the rain season the waterlogged fields caused by rainfall will be submerged with surface water at first.After that,when surface water was removed,the field will be soaked by subsurface water.Consequently,the reduction of crop production is caused both by surface and subsurface waterlogging.The benefit-cost analysis of drainage project should neither based on the single crop yield reduction caused by surface waterlogging or subsurface water logging nor the simply sum up of both reduction.In this paper,the relationship between the cotton yield reduction due to both surface and subsurface waterlogging in Huaibei region,Anhui Province,is presented,based on three years experimental data.It is also presented that the index to reflect the degree of surface and subsurface waterlogging and the methods to determine the criteria of combined controlling of surface and subsurface waterlogging.
Key words: combined controlling; surface water; subsurface water; waterlogging; drainage; sythetic index; criteria
On-line fault diagnosis of water distribution systems
LIANG Jian-wen1, XIAO
Di2, ZHAO Xin-hua1, ZHANG Hong-wei1
(1.Tianjin University; 2. Nankai University)
Abstract: This paper proposed a methodology for fault diagnosis of a water distribution system by monitoring the water pressure on-line at three nodes in the water distribution system.A neural network-based inverse analysis method was established to detect the location and extent of the fault and the affected area based on the variation of water pressure.This paper also developed a method for hydraulic analysis of a water distribution system with drainage.It was shown through an example that the methodology is effective and practical.
Key words: water distribution system; fault; on-line diagnosis; inverse analysis; artificial neural network technique; supervisory control and data acquisition(SCADA)
Influence of specimen size upon new crack extension resistance curve of concrete
ZHAO Zhi fang1,2, XU
Shi lang2
(1.Yantai University;2.Dalian University of Technology)
Abstract:The influence of specimen size upon the new crack extension resistance curve (KR curve), based on the cohesive force of concrete, in the process of fracture is studied according to the experimental results. The shape of softening traction separation law must be determined which can reflect the softening property of concrete. With regard to the bilinear softening traction separation law, by which the coordinate on X axis of the breaking point is equal to the critical crack tip opening displacement, a parameter named ¦Ë which directly affect the shape of softening traction separation law is introduced. The shape of softening traction separation law for estimation of the new crack extension resistance curve can be obtained by means of adapting ¦Ë to the experimental results. It can be seen that the new KR curve does not have size effect.
Key words:concrete£»cohesive force; new crack extension resistance curve; double K fracture parameters; softening traction separation law;size effect
WANG Shao li,ZHANG You yi,LI Fu
xiang
(China Institute of Water Resources and Hydropower Research)
Abstract:On the basis of water balance principle, the drainage modules of surface and groundwater, under the condition of combining open channel and pipe drainage, are alalyzed. The calculation method is introduced. It shows that the proposed method can fully consider the function of subsurface drainage engineering. Consequently, the investment for surface drainage can be reduced.
Key words:waterlogging; water table rising; concurrent; separate; open channel; pipe; drainage; module
Study on the behavior of clay composite specimens with sand column under undrained cyclic loading
JIANG Jun, ZHU Xiang-rong
(Zhejiang University)
Abstract: The behavior of clay composite with sand column under cyclic loading is studied experimentally by triaxial test. The effects of cyclic stress ratio, number of cycle, over-consolidation ratio, history of loading and sand replacement ratio on the behavior under the condition of undrained are analyzed.
Key words: earthquake; deformation; cyclic loading; triaxial test; composite foundation
A review of study on effect of immobile water on solute transport in unsaturated zone
WANG Li1, WANG
Jin-sheng1, YANG Zhi-feng1, WANG Zhi-ming2
(1.Beijing Normal University; 2.China Institute for Radiation Protection)
Abstract:Some solute transport model considering the effect of immobile water,adsorption and degradation are reviewed in this paper.It is pointed that the study on immobile water has been extended from dead-end water to nonmoving intra-aggregate water and isolated water.The asymmetry of breakthrough curve can be well described by mobile-immobile mode.The disk pereameter is used to measure the immobile water content directly and it makes mobile-immobile model more operational.The further studies of immobile water will be focused on the complete classify of immobile water,The effect of immobile water on water flow ,the uncertainty of the parameters and the scale effect.
Key words:immobile water; unsaturated zone; solute transport; mobile-immobile model
LI Chang-zhi, LIU Xing-nian, CAO
Shu-you, ZHANG Zhi-xiang
(Sichuan University)
Abstract: The method of principal component analysis (PCA) is applied to study the factors of sediment yield in order to understand the contribution of ante-precipitation to the sediment yield of watersheds with different conditions of sediment supply. Three data groups of ante-precipitation, rainfall in the process, duration of sediment yielding, rain intensity of two typical watersheds (the Zhuanyao Gully basin, Shanxi Province and the Jiangjia Gully basin, Yunnan Province) and an experimental area are used as variables of PCA. The mechanism of ante-precipitation in sediment yield is studied in detail. The result shows that ante-precipitation is the main contributor of the second principal component and plays a minor role in gradual sediment yield in Zhuanyao Gully. However, it is the chief contributor of the first component and plays important role in abrupt sediment yield in Jiangjia Gully.
Key words: ante-precipitation; different source of sediment; gradual sediment yield; abrupt sediment yield; principal component analysis(PCA)
Axisymmetric Biot's consolidation problems for multi-layered saturated half space
FANG Shi-sheng1,2,
WANG Jian-guo2, YANG Yong-hua3, CHEN Lin-feng2
(1.University of Science and Technology of China; 2.Hefei University of Technology;
3.Nanjing Architectural and Civil Engineering Institute)
Abstract: In this paper axisymmetric Biot's consolidation problems for multi-layered saturated soil are studied. By means of state vectors, state space equation are formulated. Using the Laplace-Hankel transforms and matrix theory, the transfer matrix of axisymmetric Biot's consolidation problems for single layer saturated clay is deduced. The cases of surface permeable and impermeable for the saturated half space are considered. According to the continuity conditions of traction and displacements at layer interfaces, the solutions of axisymmetric Biot's consolidation problems for N Layers saturated half space are presented in the integral form. The numerical example is given. The time domain solutions are obtained by applying the numerical scheme proposed by Crump, Durbin, Stehfest and Schapery for Laplace inversion. Numerical example shows that the proposed method has the advantage of high calculation efficiency and accuracy.
Key words: multi-layered saturated half space; axisymmetric problem; transfer matrix; state vector
YANG Jing-ping, CHEN Jie, YAN
Li-jiao, FAN Xing-hai
(Zhejiang University)
Abstract:The crop growth model MACROS and soil water balance module developed by Penning de Vries are adopted and modified to establish the spring corn simulation model for excessive and shortage conditions.This paper describes the modification of model structure in soil water balance and water stress under excessive paddy field,data set adaptation and gives the comparison between the simulated and measured results and statistics.The modified model is in good agreement with the actual result for the single cropping corn,while the relay cropping corn is found with large deviation.The simulated results using the spring corn model indicate that under the whole controlled soil water within 90% of field capacity condition,the heading and booting stage of spring corn is the most sensitive stage in the soil waterlogging condition.With the influence of rainfall and soil condition without any control of soil water moisture,4th and 6th leaf stage of spring corn is the most sensitive stage,then followed by the booting stage and the 8th leaf stage.According to the simulation,the critical time of soil waterlogging effect on the spring corn yield is 5 days at 4-6th leaf stage,10-15 days at the 8th leaf and booting stage of spring corn.But the continuous waterlogging with duration of 20 days will reduce the yield of corn at any development stage.Thus that the drainage of the excessive water and lowering down the soil water table are important to spring corn production in paddy field.
Key words:waterlogging; spring corn; paddy field; simulation analysis