ZHU Bo-fang
(China Institute of Water Resources and Hydropower Resources)
Abstract: A 3-D isoparametric joint element with keys of finite thickness in concrete dams for simulation calculation is introduced. It is pointed out that the magnitude of the initial clearance of joints due to shrinkage of grout is very small which can be neglected. Joints with keys can resist compression and shear but cannot resist tension. Since the horizontal stress in arch dam may be tensile or compressive the transverse joints, which can not resist tensile stress, will influence the distribution of stress in an arch dam. It is explained how this problem is related to the following factors:(1)depth of tensile stress region; (2)ratio of depth of tensile stress to spacing of transverse joints; (3)thickness of the dam and (4) climate condition at dam site. In cold region, the upper part of a thin arch dam may subject to tensile stress in full cross section during winter. In this case, the influence of transverse joints on the stress distribution in the dam is remarkable. On the contrary, the depth of tensile stress region is small for a thick arch dam in mild region, in this case the influence of transverse joints is little.
Key words: concrete dam; joint element; initial clearance; transverse joints.
LIN Gao1,CHEN
Jian-yun2
(1.School of Civil Engineering, State Key Laboratory of Coastal and Offshore
Engineering,Dalian University of Technology)
Abstract: The current practices and state-of-the-art of earthquake safety evaluation for large concrete dams with emphasis on high arch dams are reviewed. It is pointed out that the existing assessment criteria are based on the dynamic strength, especially the tensile strength of mass concrete, and linear-elastic dynamic analysis methods are used for the evaluation of earthquake stress response. However, the adopted design levels of earthquake ground motion and allowable tensile strength in different countries are diversified. In fact, every arch dam possesses its specific features and the maximum dynamic tensile stresses at some positions of the dam according to the linear-elastic response analyses is insufficient for the assessment of earthquake safety of the dam. The current criterion of concrete tensile strength is based on the limited experimental results obtained by Raphael for core specimens from five dams at a strain rate corresponding to 5Hz. Whereas, the dynamic forces at different parts in different dams will be generated with different strain rates during earthquake. In addition, the dynamic strength of mass concrete are affected also by various factors such as the loading history, the static compressive strength, the water content as well as the size effect. In this paper, the appropriate seismic safety assessment method of large concrete dams is proposed and the problems for further research are pointed out.
Key words: arch dam; gravity dam; seismic safety criteria; dynamic tensile strength of mass concrete.
NI Jin ren,LIAO
Qian,QU Yi zhong
(Center for Environmental Sciences,Peking University,The Key Laboratory of Water and
Sediment Sciences,Ministry of Education)
Abstract: Based on the conceptual two phase flow and PIC numerical method,the present paper further discussed the sediment sorting characteristics in the deposition process of the debris flow,particularly for the dilute debris flow.The model reviewed can be used for the simulation of natural debris flow of paroxysmal and unsteady characteristics.By combining the conventional Eulerian and Lagrangian methods,the E-L model can be used to describe the whole process of the typical debris flow in greater details through the elements.The present model is also proper for describing the sediment sorting accompanied with erosion and depositional processes.Varying slopes ranged from 2° to 5° were used for the input information of the model.The solid particles were divided into three groups,each corresponding to one average diameter of the particles.Other parameters were taken from the experimental data obtained in previous studies.The emphasis was laid on the sediment sorting process although other processes such as the motion and sedimentation were investigated.The modeling results show that the channel slope and the specific density of debris flow are key factors controlling the sorting process through modifying the sediment transport capacity.The larger the sediment transport capacity of the debris flow,the less solid particles are apparently sorted.The quantitative prediction of the sediment sorting characteristics is of primary importance for understanding of the deposititonal mechanism of debris flow and prevention of the debris flow disasters.
Key words: debris flow;modeling;deposition;sorting
JIN Feng, WANG
Guang lun,JIA Wei wei
(Tsinghua University)
Abstract: Employing the coupling model of distinct element boundary element,the static and dynamic analysis of underground power plant of Xiluodu Project is conducted.Some problems in distinct element simulation of underground structure are discussed.The conclusion that the distinct element method can simulate the deformation of underground structures is drawn.The effects of radiation damping can also be modeled,if distinct elements can be coupled with boundary elements.The seismic responses of underground structures will be much smaller than that of structures on the ground surface,due to effects of radiation damping.
Key words: distinct element;boundary element;coupling model;underground structure;dynamic analysis
DUAN Wen
zhong,ZHENG Ya hui,LIU Jian jun
(Wuhan university,the Key Laboratory of Water and Sediment Sciences of Ministry of
Education)
Abstract: Since 80's the water level in Chenglingji Luoshan reach of Changjiang River is much higher than it was in 50's.The rising is 1.20-1.50m in the period without rainfall and 0.50 m-0.76m in flood season.To investigate the cause of water level rising,analysis on observation data of flow discharge and sedimentation in 40 years is carried on.It is concluded that the rectification of lower reach in Jingjiang River accelerates the atresia of debouchments.Consequently,the relation between the river and lake has been changed.
Key words: water level rising;flood control;relation between river and lake;cheng lingji-luo shan reach of chang jiang river
JIAN Jin-sheng,
HAO Ju-tao, LU Xiao-bin, QU Yang
(China Institute of Water Resources and Hydropower Research)
Abstract: A new type of waterstop is developed to meet the need of the 233m high CFRD in Shuibuya Project.It is predicted that the maximum opening of the perimeter joint is 500mm and maximum subsidence is 100mm.The experimental and calculation results as well as the engineering practice show that the proposed new type of waterstop is feasible and effective.
Key words: perimeter joint; high CFRD; waterstop
DENG Zong-cai
(Tsinghua University)
Abstract：The result of experimental investigation of failure behavior of carbon-steel fiber reinforced concrete under compressive loading is presented.The effects of fiber type,fiber volume and stress/strength ratio on fatigue resistance and energy adsorption are studied.The characteristics of damage accumulation in concrete are also studied.It is found that fiber reinforced concrete may dissipate much more additional energy under low stress level and has logner life than that of high stress level.
Key words：carbon fiber; steel fiber; reinforced concrete; fatigue; damage
ZHANG Yu
fang,ZHANG Wei zhen
(Wuhan University of Hydraulic and Electric Engineering)
Abstract：The methods for determining the drainage design criteria to meet the requirements of crop yield increase and environment protection, under the condition of planting paddy after winter wheat, are investigated. In this cropping pattern, winter wheat always suffers from water logging due to excessive rainfall and rise of groundwater in growth period. During the growth period of paddy, the unfavorable condition for soil aeration due to long term submergence of ponding irrigation causes the reduction of yield of paddy rice. However drainage system will increase the loss of fertilizer and contaminate the water in rivers and lakes. Thus, reasonable drainage criteria are needed.
Key words：cropping pattern；paddy；winter wheat; water logging; loss of fertilizer; drainage design criteria
CAI De-suo1，HE Xing-ji1,ZHANG Ling2
(1.Three Gorges University;2.Sichuan University)
Abstract: The distributed optical fiber sensing technology is applied to detect the cracks in the small scale plaster model test fo arch dam.The practice of this technology shows that the sensor network sticked on the downstream surface of the dam will not affect the strffness of the model,but it must be correctly distributed.By using OTDR the real time monitoring of cracks can be realized.
Key words: arch dam;plaster model;optical fiber sensing;crack; small scale
CAO Wen-hong,
ZHANG Qi-shun, HU Chun-hong
(China Institute of Water Resources and Hydropower Research)
Abstract: Based on the energy equilibrium principle and diffusion theory, the expressions of transverse distribution of suspension concentration inside and outside of the breaking wave zone are deduced. It is found that the concentration inside of the breaking wave zone near the coastline is not equal to zero, which is in agreement with the measured data. Since the setting velocity is included, these expressions are more reasonable than those deduced from Fick's model, in which the setting velocity is not being considered.
Key words: breaking wave zone; suspended sediment concentration; sediment setting velocity; particle lifting; sediment transport
FENG Shao-yuan1，DING Yue-yuan2,ZENG
Xiang-hui3
(1.China Agriculture University;2.Beijing Institute of Hydraulic Research;3.Beijing Water
Technology Center)
Abstract: Based on the theory of soil water dynamics and root water uptake of tomatoes,a mathematical model is developed to simulate the soil water infiltration,redistribution and extraction.The model is solved by ADI difference procedure coupling with Gauess-Seidel method.The calculation results of soil water pressure well agree with the observation data.
Key words: drip irrigation;soil water movment;numerical simulation;ADI difference procedure;Gauess-Seidel method
MA Ke sheng1,GONG
Xiao nan2
(1.Taiyuan University of Technology;2.Zhejiang University)
Abstract：Based on the layered shear displacement method, perturbation method and random field theory, this paper presents a simplified method for calculating the settlement reliability index of flexible piles. The precision of this method is verified by SFEM and Monte Carlo method. It is found that the probability model has little effect on reliability index, if the variation of soil deformation modulus is small, and the normal distribution can be selected as the probability model of soil. When the deformation modulus of soil is logarithmic normal distribution, even if the variation is large, reasonable precision can be obtained by center point method, in which the deformation modulus of soil is normalized equivalently.
Key words：reliability; simplified formula; random；flexible pile
ZHENG Yong
hong,SHEN Yong ming,QIU Da hong
(Dalian University of Technology)
Abstract: Based on the original hyperbolic mild slope equation,a nonlinear dispersion relation is introduced to take the nonlinear effect of waves into account.The improvement of the numerical scheme elevates the calculation speed and efficiency in solving the hyperbolic mild slope equation.The nonlinear dispersion relation and the improved numerical scheme are applied to the calculation of water waves over an elliptic shoal.The result is satisfactory.
Key words: nonlinear dispersion relation;hyperbolic mild slope equation;numerical calculation;water waves
CHEN De-xin, XIE
Hui
(North China Institute of Water Resources and Hydropower)
Abstract：The pressure distributions of the Francis pump-turbine runner are measured in model test and the flow is visualized by using tracer method.The flow patterns are analyzed according to the receorded video pictures.The unstable flow in S-shape characteristic region is discussed.
Key words：pump-turbine; S-shape characteristic; image processng
ZHANG Hui
(Kunming Geotechnical Engineering Corporation)
Abstract：The expression of representative elementary volume(REV) for permeability of saturated rock is deduced by statistic analysis. The relation between saturation degree and representative elementary area(REA) for permeability of a single unsaturated fracture is discussed by mechanism analysis. Based on the hypothesis of “similar expansion from REA to REV”,the similar correspondent relationship between REV for permeability of saturated rocks and REA for permeability of a single unsaturated fracture is established. The results show that the REA for permeability of a single fracture under middle saturation degree is relatively small, and that for permeability of a single fracture under high or low saturation degree is relatively large. In case study, the relation between REA for permeability of a single unsaturated fracture and the saturation degree is analyzed quantitatively by using the stochastic homogeneous distribution of apertures. The REV for permeability of unsaturated rocks is derived based on the hypothesis of similar expansion from REA to REV.
Key words：rock masses；seepage flow；saturation;permeability; representative elementary volume; aperture
ZHANG Qina-fei,
GU Chong-shi, WU ZHong-ru
(Hohai University)
Abstract: The lag effect function is introduced to take lag effect of level and rainfall into account in establishing monitoring model for seepage flow in rockfill-earth dam.The calculation result shows that the proposed model correctly reflects the influence of lag effect and possesses high precision in seepage prediction.
Key words: lag effect; lag effect function; rockfill-earth dams; seepage flow; monitoring model
LUO Yi1, YU
Qiang, OU-YANG Zhu, TANG Den-ying
(1.Yucheng Comprehensive Experiment Station,CAS)
Abstract：An integrated model for simulating the interaction among soil water dynamics,soil evaporation and crop transpiration,CO2 flux as well as the photosynthesis in SPAC is established in this paper.In the model,sol profile is divided into adjacent compartments and the soil water dynamics is modeled with sets of water balance equations.Crop water uptake by root is modeled with a modified version of Feddes model.The soil evaporation and crop transpiration are calculated according to the Wallace formula.Two schemes for canopy resistance modeling are proposed.In the first scheme,canopy resistance and photosynthesis are modeled by scaling up leaf-scale model suggested by the authors.In the another scheme,Dickinson's canopy resistance model is proposed when it is not required to or the data are not enough to estimate the photosynthesis and CO2 flux.
Key words：SPAC; evaporation and transpiration; photosynthesis; CO2 flux; root water uptake