Runoff Variation and Its Impacting Factors in the Headwaters of the Yangtze River in Recent 32 Years
ZHU Yan-long1 , CHEN Jin2a , CHEN Guang-cai2b
(1.Qinghai Hydrology Bureau, Xi’ning 810001, China; 2.Yangtze River Scientific Research Institute, Wuhan 430010, China)
Abstract: The runoff data measured from 1978 to 2009 at Zhimenda hydrological station in the headwaters of Yangtze River are analyzed by Mann-Kendall test and slide T test to study the trend of runoff variation. Impacting factors including precipitation, temperature, and underlying surface condition are also elaborated in this paper. The results show that the overall annual runoff increased slightly during 1978-2009; while there was an abrupt change around 2004 according to slide T test. With regard to the impacting factors, the annual precipitation witnessed slight changes in general and a sudden change around 2002, and the annual air temperature series within the basin increased remarkably. It is concluded that the runoff increase during 1978-2009 is mainly caused by the increase of precipitation and ice melting.
Key words: headwaters of the Yangtze River; runoff variation; climate change
Multidimensional Weighted Dynamic GM(1,1) Model Applied in the Prediction of Dam Deformation Degree
CUI Dong-dong, CHEN Jian-kang, WU Zhen-yu, CHENG Li-ming
(College of Water Resource and Hydropower, Sichuan University, Chengdu 610065, China)
Abstract: The prediction result of GM(1,1) grey model is subject to be disturbed by outdated information previously measured in the system, while one-dimensional dynamic GM(1,1) model is restrained by the selection of the dimension. To overcome these problems, this paper studies the content and the modeling of Multidimensional Weighted Dynamic GM(1,1) model (MDWD-GM(1,1) model) in detail. Based on the prediction results of all the dimensions calculated by this model, the weight value of each dimension is obtained by Sa function weighting method and BP neural network, then the final predictive value is obtained by weighting. Moreover, the MDWD-GM(1,1) model has been applied to the dam monitoring system and the application manifests that it offers better prediction results than traditional GM(1,1) model and one-dimensional dynamic GM(1,1) model as it takes the effect of different dimensions into account and increases the white degree of the grey range by updating the data in time.
Key words: GM(1,1) model; one-dimensional dynamic GM(1,1) model; multidimensional weighted dynamic GM(1,1) model; weight; BP neural network; the Sa function
Critical Technical Issues of Diversion and River Closure Construction Under Deep-Thickness Covering Layer Condition
GUO Xi-ling, HUANG Guo-bing, LI Xue-hai
(Yangtze River Scientific Research Institute, Wuhan 430010, China)
Abstract: By theoretical analysis and model experiment, the features of different kinds of covering layers and the problems existing in the construction of diversion and river closure are analyzed. Critical technical issues under deep-thickness covering layer condition such as the covering layer stability , the covering layer protection, the stability calculation of closure block, the artificial block stability and the preventive measures against embankment collapsing in alluvial riverbed are studied also. In addition, the practical computation formula for block stability is improved, and the empirical equations for the stability calculation of hexahedron steel reinforcement cage are deduced. It is the first to put forward that the stop- move stability of tetrahedron steel reinforcement cage is obviously better than that of hexahedron steel reinforcement cage, yet their start- move stability differs slightly.
Key words: deep-thickness covering layer; diversion and river closure construction; bottom protection measures; block stability; steel reinforcement cage; stability calculation
A Random Sampling Algorithm for Identification of Turbulent Prandtl Number
ZHU Song1 , LIU Guo-hua2 , CHENG Wei-ping2 , HUANG Yue-fei3
(1.Water Engineering Department, Guangdong Electric Power Design Institute, Guangzhou 510663, China; 2.College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China; 3.State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China
Abstract: Turbulent Prandtl number (Pr) is a key parameter for controlling the temperature distribution in the research of thermal discharge water and other environmental hydraulics involving heat transfer. For a given problem, turbulent Pr number generally comes from previous experiences or trial-and-error method, which is blindfold and inefficient. To increase the reliability of turbulent Pr number for a given problem, Metropolis-Hastings algorithm, a Markov Chain Monte Carlo (MCMC) random sampling method was employed in this paper to identify turbulent Pr number. In the numerical simulation, steady standard k- ε model was used for turbulence flow field computation, while unsteady heat transfer equation was adopted for computing the temperature field. The computation results manifested that MCMC method is suitable and can offer precise results for the identification of turbulent Pr number.
Key words : turbulent Prandtl number; parameter identification; turbulent heat transfer; Metropolis-Hastings algorithm; MCMC random sampling
Dumping Materials for Reducing the Difficulty of River Closure and Dike Protection
CAI Ying, HUANG Guo-bing, CHE Qing-quan, YANG Wen-jun
(Yangtze River Scientific Research Institute, Wuhan 430010, China)
Abstract: To select applicable dumping materials and optimize their performance is one of the measures of reducing the difficulty of river closure. In light of the physical properties of cylindrical material and hydraulic model tests of river closure, the cylindrical wire materials are dumped along the slope surface, rolling down to the deep trough of the closure gap easily and remaining quite stable underwater. Cylindrical wire dumping material proves to be capable of protecting the closure dike from collapsing and preventing river closure materials from losing. Moreover, it has apparent advantages in terms of material saving, production, storage and transportation. It is also presented that cylindrical wire dumping material can be used in the emergent construction and supporting of river embankments and dams.
Key words: dumping material; river closure difficulty; dike protection; cylindrical wire material; collapse; loss
Scouring Mechanism in Front of the Sluice of Low-Head Hydro-Projects
FANG Sen-song , LIU Xiao- ping , WU Guo-jun, ZHOU Qian- kai, QIAN Dong-yue
(School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410076, China)
Abstract: To elaborate on the river bed scouring in front of the sluice of low-head hydro-projects, physical and mathematical models are built to study the three dimensional flow in front of the sluice. Movable bed physical model is used to observe the development process of the scouring pit. Furthermore, fixed bed physical model and three-dimensional turbulence model are employed to simulate the 3-D flow field at the initial, middle and steady period of the scouring. The main conclusion is obtained as follows: at the beginning of scouring, as the flow is obstructed by the sluice, vortexes are formed by the diving flow and a complicated three dimensional flow is generated, thereby causing a large amount of sediment activating in front of the sluice structures. Accordingly, it results in scouring in front of sluice structures rapidly. During the middle and later period, the diving flow in the scouring pit is gradually weakened along the water depth direction, hence the vortex disappears, and the development of the scouring pit slows down and finally reaches equilibrium.
Key words: low-head hydro-project; sluice; scouring pit; diving flow
Flow Measurement Methods Under Low Flow Velocity at the Tributary Bays of Three Gorges Reservoir
MA Jun1 , LIU De-fu1, JI Dao-bin2 , YANG Zheng-jian1 , YI Zhong-qiang1
(1.School of Hydraulic & Environmental Engineering of Three Gorges University, Yichang 443002, China; 2.School of Water Resources & Hydropower, Wuhan University, Wuhan 430072, China)
Abstract: After the impoundment of Three Gorges Reservoir, parts of the tributaries in Three Gorges Reservoir area are influenced by the backwater of Yangtze River mainstream, giving birth to tributary bays. The water flow pattern changes from typical river pattern to lake-like pattern. Hydrodynamic conditions of the bay hence become extremely complex under the combined effect of factors like the upstream inflow and reservoir operation. In view of this, a unique flow velocity monitoring method is presented based on long-term field observation and the complex hydrodynamic condition of the bays. By using this method in Xiangxi River Bay, better flow measurement results have been obtained. It can better characterize the hydrodynamic property of water bodies of the bays under low-flow condition, and therefore proves to be an effective method.
Key words: Three Gorges Reservoir; tributary bays; flow measurement; acoustic Doppler 3D velocimeter; ADCP 4
Influences on Navigation Conditions of Yichang Yangtze River Bridge on Yichang-Wanzhou Railway
(China Railway Fourth Survey and Design Institute Group Co., Ltd., Wuhan 430063, China)
Abstract: To minimize the adverse impact of bridge construction on the navigation in bridge area, two bridge sites to be selected for Yichang Yangtze River Bridge are compared in the first place, and the impacts of different bridge types on the channel in the bridge area are studied by real ship test and navigation hydraulics and ship model test. The study manifested that for both the sites, flow regime change caused by bridge construction only happens near the bridge pier and in the downstream area of the bridge pier; while the water level rises only in a short distance of the upper reaches(the free-surface increment at 150 m upstream of the bridge is 0.1 m, yet with no obvious change downstream before and after the bridge construction). Finally, comprehensive analysis showed that the optimized No.2 bridge site scheme is more appropriate. The study provides scientific basis for the design of this project, and serves as a reference for the construction of other large cross -river bridges as well.
Key words: Yichang-Wanzhou railway; Yichang Yangtze River bridge; navigation
Further Discussion on Dilatancy Model for Coarse-Grained Soils
CHENG Zhan-lin1 , CHEN Ou1,2, ZUO Yong-zhen1 , DING Hong-shun1
(1. Key Laboratory of Geotechnical Mechanics and Engineering of MWR, Yangtze River Scientific Research Institute, Wuhan 430010, China; 2. College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China)
Abstract : The test results of large triaxial test and plane strain test for two kinds of coarse-grained soils are firstly described. Soil strain is assumed as two parts composed of elastic strain and dilatancy strain. The relationship of elastic strain and stress is supposed to obey generalized Hooke's law; while the dilatancy strain obeys Rowe dilatancy law, and the elastic Poisson’s ratio is assumed as constant. Based on these assumptions, the relationship between stress and three parameters including volumetric strain module Kp, dilatant module Kq , and shear module G is established, and a new nonlinear dilatancy model which is simple and practical with clear physical concept is preliminarily proposed. Subsequently, the collation method of the model parameters is given, and finally the mechanical significance of Poisson’s ratio of the general nonlinear elastic model is demonstrated. The tests indicate that the model can well simulate the stress-strain curve for different coarse-grained materials. As for the same coarse-grained soils, the model parameters from the triaxial test and plane strain test are consistent except for the strength index. Model parameters for two kinds of coarse-grained soils are also offered.
Key words: stress-strain relationship; constitutive model; plane strain test; dilatancy; coarse-grained soils; earth and rockfill dam
Seepage Stability Analysis for the Overburden Layer of Dam Foundation at a Hydropower Station
WANG Zhi-hong1 , REN Guang-ming1 , ZHAO Hai-ying2 , LIU Yan-ling2
(1.State Key Laboratory of Geological Hazard Prevention and Geological Environment Protection, Chengdu University of Technology, Chengdu 610059, China; 2.Northwest Investigation Design and Research Institute, Gansu 730050, China)
Abstract : The seepage stability of the overburden layer of a dam foundation is studied in this paper to provide basis for seepage control for the dam. Firstly, according to the geologic and hydrogeologic characteristics of the dam foundation overburden layer, the seepage deformation type is preliminarily estimated based on hydrogeological parameters obtained from site and indoor tests. A 3-D numerical model of the overburden layer is subsequently built to get the characteristics of seepage field and hydraulic gradient based on the above parameters and seepage theory so as to analyze the leakage amount of reservoir water permeating through the overburden layer under different operation conditions. In view of the above study, the simulation results of hydraulic gradient under different conditions are analyzed to assess the seepage stability of the dam foundation, which is further compared with the preliminary estimate so that the final conclusion can be derived.
Key words: overburden layer; leakage amount; seepage stability; hydro-geologic model; hydraulic gradient
Microevolution Algorithm for Inversion of Non-stationary Parameters in Rock Creep Model
PENG Ru-fa, XU Xiao-jian
(Wuhu Geotechnical and Survey Design Institute, Wuhu 241000, China)
Abstract: Rock creep model generally contains several parameters. To obtain the global optimal solution of the parameters, Microevolution Algorithm (MA) was employed for the inversion of non-stationary parameters. In this paper, parameters of the creep model are directly inversed with the least square error between measured creep values and calculated creep values as the optimization criterion function. The computation results demonstrate that microevolution algorithm can maximize the use of all test data and avoid the difficulty of selecting initial parameters in traditional optimization algorithm. Moreover, microevolution algorithm is simple and effective, and offers higher accuracy than Chaos Particle Swarm Optimization (CPSO). In this sense, it can be applied to the inversion of parameters in other creep models and has high application value for engineering.
Key words: rock creep model; inversion of non-stationary parameter; microevolution algorithm
Characteristics of In-situ Stress Field in Baotashan Extra-long Tunnel
GUO Xi-feng1, ZHANG Ming-xin2 , YIN Jian-min1, LIU Yuan-kun1
(1.Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Yangtze River Scientific Research Institute, Wuhan 430010, China; 2.Shanxi Provincial Communications Planning, Survey and Design Institute, Taiyuan 030012, China)
Abstract: Baotashan tunnel is the longest highway tunnel in Shanxi province with a full length of 10 480 m and a maximum burial depth of 600 m . The complex topography and geomorphology and geological structures give rise to a complicated in-situ stress distribution in the tunnel area. To study the characteristics of rock in-situ stress field in the tunnel area, this paper firstly present the measured results of geostress by hydro-fracturing method, based on which the stress profile along the tunnel is obtained by FEM analysis, and finally the regional tectonic stress field is comprehensively analyzed from perspectives of topography and geomorphology, geologic structure, and geomechanics. The research manifested that in -situ stress in the test area can be defined as middle level stress, and the maximum horizontal principal stress in the tunnel design elevation is mainly concentrated in N42 ° E~N56 ° E, and regional tectonic stress field is consistent with in-situ stress field achieved by site test and numerical simulation.
Key words: tunnel engineering; stress measurement; finite element analysis; stress field characteristic
Risk Analysis for Tunnel Rockburst Based on Fracture Mechanics and Stochastic FEM
ZHAO Yan-xi, LI Hao
(Jiangsu Provincial Communication Planning and Designing Institute Co., Ltd., Nanjing 210005, China)
Abstract: Stress-strength ratio model is usually applied to rockburst prediction in China and abroad, but uncertainties in engineering are not taken into account in this method. A fracture mechanics model of rockburst mechanism is proposed in this paper. This model is based on the assumption that rockburst is caused by microcracks which parallel to the free surface. These microcracks will fracture, extend, and mutually connect under external load. Then visible macroscopic crack is formed and finally rockburst happens. Furthermore, a rockburst risk probability model is proposed using reliability theory and stochastic FEM method based on Lamination spallation buckling model. The model was applied to engineering project calculation and the result manifested its rationality.
Key words: rockburst; deep-buried tunnel; fracture mechanics; stochastic finite element method
Fluid-Solid Coupling Analysis of Dam-Reservoir Interaction
GONG Ya-qi, SU Hai-dong, CUI Jian-hua
(Yangtze River Scientific Research Institute, Wuhan 430010,China)
Abstract : Dam-reservoir interaction was analyzed in this paper using fluid-solid coupling method. The reservoir water was modeled respectively by two types of finite element, namely pressure-based element and displacement-based element. The fluid-solid coupling method was compared with traditional Westergaard additional mass method and the comparison showed that the former was closer to the theoretical solution than the latter. The displacement-based element demanded more regular element shape than pressure-based element. Moreover, sensitivity analysis of selected areas of the reservoir showed that satisfactory results can be obtained if the length of reservoir area to be modeled was designed only 3-5 times the height of the dam. Finally, the compressibility of water was also explored taking the gravity dam structured model with different dam crest widths as an example. The present results will be helpful for the following research.
Key words: fluid-solid coupling; hydrodynamic pressure; natural frequency; compressibility
Fuzzy Comprehensive Evaluation on the Stability of Reservoir Bank
LUO Yi, REN Guang-ming, WANG Zhi-hong, SONG-Yang
(National Key Laboratory of Geohazard Prevention and Geo-environment Protection, Chengdu University of Technology, Chengdu 610059, China)
Abstract: Quantitative assessment of the stability of reservoir bank is a complicated systematic engineering as the selection of evaluation index and the establishment of evaluation system are based on qualitative cognition; while the relevance and independence between evaluation factors and reservoir bank are reflected by mathematical indicators including weights and the degree of membership. In this paper, fuzzy comprehensive evaluation is used to evaluate a 72.4 km long reservoir bank of a hydropower station. Being consistent with the results of site survey and remote sensing, the evaluation results are highly valuable.
Key words: stability of reservoir bank; fuzzy comprehensive evaluation; weight; degree of membership
Synchronous Replication Technology of Heterogeneous Database and Its Application
HU Jin-long1 , XU Wei2 , FANG Fu-long1 , LI Gang1 ,CAO Xiao-ning1
(1.Jiangsu Provincial Hydrology & Water Resource Survey Bureau, Nanjing 210029,China; 2.Geo-engineering Yangtze Australia Co.Ltd., Yangtze River Scientific Research Institute, Wuhan 430010,China)
Abstract: It is the basic requirement of daily business management and the main purpose of informatization construction to share information resources. Nonetheless, the lack of overall planning and technical standard stipulation during the informatization construction lead to the involvement of various database management systems of different types and structures, which makes it hard to unify the table structure, technical system and software application of the database management system, directly affecting the effective and extensive sharing of common information resources. Taking the automatic hydrological telemetry and precaution system integration in Jiangsu Province as an example, this paper analyzed the Heterogeneous Database(HDB) and then studied the synchronous replication technology and the application methods among the HDBs. The study was made by database replication of mature distributed database techniques in coalition with concentrated and autonomous control mechanism. The study was meant to solve the information sharing problems of the HDBs so that the distributed database system can be more reliable and timely, and be used universally. It is also aimed at providing an effective plan for data sharing and synchronization, as well as a mature, effective technique easy to use for the integration of systems among HDBs so that all data are synchronized and unified partly or completely. The data replication technology of distributed HDBs recommended in this paper is easy to operate and simple in terms of defining parameters and configurating the systems, and is also completely heterogeneous, DBMS independent, reliable, and can be used more widely.
Key words: heterogeneous; distributed; database; replication
Study on Flow Characteristics of Jingjiang River
QU Geng1,2 , ZHU Yong-hui1 , TANG Feng1 , SUN Gui-zhou1
(1.Key Laboratory of River Regulation and Flood Control of MWR, Yangtze River Scientific Research Institute, Wuhan 430010, China; 2.State Key Laboratory of Water Resource and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China)
Abstract: The Yangtze River Flood Protection Physical Model is employed to comprehensively measure the hydraulic elements for different flow discharges of Jingjiang river. Furthermore, the water sediment and topography data since the impoundment of Three Gorges Reservoir were taken to analyse the general laws and characteristics of flow movement. Based on the above analysis, different river regulation programs are studied and detailed solutions for different river regimes are offered. The study reveals the flow movement rules for Jingjiang River by clearly presenting the inherent laws of hydraulic elements variation including that of the water level, water surface longitudinal slope, breadth to depth ratio of cross section, flow velocity distribution and dynamic axis of flow, and consequently provides scientific basis for river regulation.
Key words: Yangtze River Flood Control Physical Model; Jingjiang River; flow characteristics; river regulation
Modeling Method of Flow Diversion of the Three Outlets in Jingjiang Reach Under Unsteady Flow Conditions
ZHU Yong-hui, QU Geng, GUO Xiao-hu
(Yangtze River Scientific Research Institute, Wuhan 430010, China)
Abstract : The Yangtze River Flood Protection Physical Model is built under the financial support of World Bank loan. Based on theoretical analysis and experimental study, a modeling method of flow diversion of the three outlets in Jingjiang Reach under unsteady flow conditions was established for the model. Validation tests under both steady and unsteady flow conditions manifested that with this modeling method, the experimental flow diversion proves to be consistent with that of the prototype and therefore meets the requirements for precision. Being validated, this modeling method has been applied to Yangtze River Flood Protection Physical Model to study the flood routing features in Jingjiang reach.
Key words: the three outlets in Jingjiang reach; flow diversion; unsteady flow; Yangtze River Flood Protection Physical Model; curved weir; modeling