Concrete splitting tensile strength and failure criterion for different loading rate and lateral stress

SONG Yu-pu, LU Pei-yin, HOU Jin-pen
(Dalian University of Technology)

Abstract: The splitting test result of 64 concrete specimens under four kinds of lateral stress and four loading rates is presented. The effect of loading rate on concrete splitting tensile strength for different lateral stresses is studied. The regression formula of concrete failure criterion for various lateral stresses and loading rates is obtained on the basis of experimental data.

Key words: concrete splitting tensile strength; lateral stress; loading rate; failure criterion; experimental study.

A preliminary study on sediment-removing capacity and river motion dynamics

WANG Zhao-yin^1,2, WU Yong-sheng², LIU Fang²
(1.International Research and Training Center on Erosion and Sedimentation;2.Tsinghua University)

Abstract: Sediment-removing capacity is defined as the capacity of the flow to remove sediment from per unit length of a river section to other places per time.Differing from the well defined sediment carrying capacity,which is the feature of the mean flow and explains how much sediment load the flow can transport through the channel,the sediment removing capacity is the feature of unsteady,non equilibrium flow and represents the capability of the flow to change the channel shape and location.Measurement of the sediment removing capacity was performed at 12 cross sections of the wandering lower Yellow River.Analysis demonstrates that the removing capacity depends mainly on the fluctuation intensity of the flow discharge.The power spectrum of discharge is presented with Fourier transformation and it revealed the mechanism of high measurement frequency high sediment removing capacity.The movement of a river channel within the fluvial plain is defined as the river motion.The patterns of river motion are aggradation,degradation,widening,translation,rotation,wandering,bifurcation,and migration from one channel to another channel.The speed of the river motion is given as a function of the sediment removing capacity.

Key words: sediment-removing capacity; river motion; fluctuation intensity of flow discharge; power spectrum; Lower Yellow River.

Optimized operation scheme for deposition reduction and enhancement flood control capacity
of Three Gorges Project reservoir

ZHOU Jian-jun¹, LIN Bing-nan², ZHANG Ren¹
(1.Tsinghua University;2.China Institute of Water Resources and Hydropower Research,)

Abstract: Based on the previous double flood control level scheme of operation proposed by the authors, a new scheme for further reducing the deposition and enhancing the flood control capacity of the TGP reservoir is presented.It is suggested that the impounding level should be raised to 148-150m in flood season when discharge is smaller than 35000m³/s and lowered to 143m otherwise,and furtter lowered to 135m when large flood of frequency smaller than 10% is predicted.The advantage of this new scheme is to further enhance the sluice capacity and minimize the possibility of blocking up of navigation due to sediment deposition.At the same time,the flood control capacity and power generation may also be increased.

Key words: The Three Govges project;flood control level; deposition reduction; flood control capacity; optimization

Localization analysis of arch dams

YANG Qiang, CHEN Xin, ZHOU Wei-yuan
(Tsinghua University)

Abstract: Based on the Ottosen'to-plastic material,the localization analysis of arch dams is incorporated with the FEM package TFINE.The analysis of a thin concrete plate under the action of compression is given as an example for demonstration.The calculation shows that a shear failure band exists.The analyses for two arch dams are also carried out.The results show that localization will firstly occur at dam heel and dam toe,but the final failure mode depends on the dam shape.

Key words: strain localization; critical hardening modulus; critical bifurcation direction

3-D feedback analysis based on the observational deformation of concrete face rockfill
dam in Tianshengqiao Project

GAO Lian-shi¹, SONG Wen-jing¹, ZHANG Zong-liang², FENG Ye-lin²
(1.Tsinghua University;2.Kunming Design Institute of State Power Corporation)

Abstract: According to the observed data both in the period of construction and in the process of first impounding,the feedback analysis of the CFRD dam in Tianshengqiao Project was carried out using 3-D FEM incorporated with K-G model.The result accords with the deformation measured in-situ.The result also illustrates the mechanical properties of rockfill material and reveals the complicated characteristics of high CFRD having different areas of material and many construction stages.On this basis,the authors suggested that it is improtant to improve the compaction of the material in the downstream side of the dam,particularly to optimize its temporary sections during construction,so as to control the differential deformation and to prevent from occurrence of cracks in cushion and voids between the cushion and concrete face plate.

Key words: high CFRD; observational deformation; nonlinear uncouple K-G model; feedback analysis; optimization of temporary section

Numerical simulation for the flow field of vertical round turbulent jet entering the cross current

ZHANG Xiao-yuan, LI Wei, LI Chang-cheng
(Wuhan University)

Abstract: The standard κ-εmodel and hybrid finite analytic method(HFAM) are applied to numerically analyze the flow field of the vertical turbulent round jet entering the uniform cross free stream. The calculated trace of the jet is in good agreement with experimental data and theoretical analysis. The universal mathematical expressions of the jet trace and its boundaries for various jet flow ratio(the ratio of jet emitting velocity to cross flow velocity) are deduced. Furthermore, the dependence between maximum width of effective region of tracer with jet flow ratio, the relationship between deflection of maximum concentration point from jet center and jet flow ratio in different elevation are deduced. The conditions for occurrence of the jet stick to the wall and probability of jet bifurcation are also investigated.

Key words: vertical round turbulent jet; flow field; cross flow; numerical simulation.

The effect of flap height on wall pressure distribution

ZHANG Pan feng, WANG Jin jun, ZHAN Jing xia
(Beijing university of Aeronautics and Astronautics)

Abstract: The effects of flap height and the gap between flap and wall on pressure distribution are investigated experimentally in wind tunnel. The result shows that the height of flap does not influence the relative location of separation point, reattachment and main vortexes in case no gap exists but the relative height of the secondary vortex increases with the height of the flap resulting in the decrease of non dimensional pressure coefficient in the vicinity rear to the flap. When the relative gap height (the ratio of flap height to gap width) is in the range of 0.8-2.0, the mean pressure will reduced 30% if the flap height is smaller than the thickness of boundary layer. The influences of gap with different height on pressure distribution are in the same manner.

Key words: separation; flow reattachment;flap; pressure distribution

Application of damage interface model for 3-D FEM analysis

HU Li-ming, PU Jia-liu, WANG Gang
(Tsinghua University)

Abstract: The damage interface model proposed is briefly introduced and the implementation of 3-D interface element is discussed.The slippage problem is analyzed and the rationality and advantage of the model are demonstrated by comparison of calculation results of different interface models.In addition,the deformation and stress of cutoff wall in a cofferdam are analyzed and the result is verified to be reasonable.It is shown that the damage interface model is able to well describe the problems of soil-structure interaction and can be used in numerical analysis in engineering practice.

Key words: soil-structure interface; strain softening; damage model FEM analysis

Comparison of crop water requirements computed by single crop coefficient approach and
dual crop coefficient approach

PAN Yin-qin, CAI Huan-jie
(Northwest Science and Technology University of Agricultural and Forestry)

Abstract: This study is to evaluate the water requirement of crop(ET) using single coefficient approach and dual crop coefficient approach under the condition of Shannxi Province and to compare ET estimation with observation data measured by lysimeter.The differences are analyzed.The result shows that dual crop coefficient approach is better than single crop coefficient approach in case the field is partly covered.However,the difference is insignificant if the field is fully covered.

Key words: crop water requirement; lysimeter; single; dual; crop coefficient

Application of ecology engineering to solving environmental problems in construction of hydro project

CHENG Fei
(Daao Water Conservancy and Hydroelectric Development Company)

Abstract: Based on the basic theory of ecology engineering and combining with the theories of construction for hydro project,some principles for solving environmental problems in hydro project construction are proposed.According to the theory of ecology economics the ecology engineering system for hydro project construction is established.The successive order analysis method is applied for solving.An example is given for demonstration.The problems to be solved are planning of land utilization,storing of material and dump,etc.

Key words: hydro project; environmental problem; ecology engineering; construction planning

Algorithm for reverse proposition of fuzzy optimization and its application in flood control decision-making

CHEN Shou-yu, LIU Jin-lu, FU Guang-tao
(Dalian University of Technology)

Abstract: The algorithm for solution of the reverse proposition of multi-objective decision-making fuzzy optimization model,proposed by CHEN(1993),is studied.Two approaches matching the intention of decision maker for computing objective weight are suggested:1)the algorithm for linear equation set based on Hamming range;2) the formula for computing objective weights in fuzzy pattern-recognition.Meanwhile,two approaches are applied to compute objective weights in Fengman Reservoir flood control decision-making.

Key words: reverse proposition; multi-objective; objective weight; reservoir flood control operation

Water saving mechanism for promoting water use efficiency by using alternate furrow irrigation techniques

SUN Jing-sheng^1,2, KANG Shao-zhong², CAI Huan-jie², HU Xiao-tao²
(1.Farmland Irrigation Research Institute; 2.Northwest Sci-Tech University of Agriculture & Forestry)

Abstract: Based on the research finds at home and abroad,the water saving mechanism to promote water use efficiency by using alternate furrow irrigation technique was discussed in the aspects of field water storing efficiency,the efficiency of sol water storage changing into water absorbed by root system,the leaf stomatal behavior,the transformation of photosynthetic output among the different crop organs,etc.It is shown that alternate furrow irrigation technique obviously reduces the inter-row evaporation,optimizes the stomatal behavior,decreases the crop transpiration and influences the photosynthesis unremarkably so as to elevate the crop water use efficiency greatly.

Key words: alternate furrow irrigation; water use efficiency; water saving mechanism

Numerical-analytic method for reservoir backwater storage flood routing

XU Hai-jun, CHEN Shou-yu
(Dalian University of technology)

Abstract: The effect of back-water storage on flood routing of reservoir is theoretical explained and demonstrated by examples.The numerical-analytic method is applied to solve the problem.By using this method,the calculation of flood routing will be more convenient and more accurate.An example is given for demonstration.

Key words: reservoir; back water storage effect; flood rooting; numerical-analytic solution

Simplified analysis of transverse vibration for inhomogeneous earth rock dams in triangular canyons

SHEN Zhen zhong, XU Zhi ying
(Hohai University)

Abstract: An approximate method is proposed for evaluating the transverse earthquake responses of inhomogeneous earth rock dams in triangular canyons. Assuming the shear modulus is varied with depth as an exponential function and based on the 3-D shear wedge theory, the control differential equation of transverse vibration for earth rock dams is derived. Using the variable separation and Bubnov Galerkin method, the algebraic formulas for calculating the free frequencies of the first, second and third mode are deduced. On the basis of technique for response spectrum, the formulas for calculating the maximum values of earthquake response such as maximum dynamic displacement, maximum velocity, maximum acceleration and maximum stress are obtained. An example is given for demonstration.

Key words: earth rock dam; transverse vibration; vibration mode; earthquake response; response spectrum

Rock-mass block index and its engineering practice significance

HU Xie-wen¹, ZHONG Pei-lin²,REN Zhi-gang³
(1.Southwest Jiaotong University;2.Sichuan Central Monitoring Station of Geological Environment；
3.Chengdu Hydroelectric Investigation and Deaigning Institute)

Abstract: Rock-mass block index (RBI) for indicating the properties of rock is proposed. The index is defined as the sum of weighted drill-core recovery ratio for differnet lengths. Based on the current code for classification of rock-mass structure in China, 5 grades of length are suggested, namely 3-10cm,10-30cm,30-50cm,50-100cm and >100cm. The correlation analyses of relationship between RBI and rock quality designation, RBI and coefficient of rock-mass sound-degree, RBI and deformation modulus of rock-mass show that the RBI can synthetically reflect the rock-mass block properties and its structure.
Key words: rock-mass structure; rock quality designation; rock-mass block index(RBI)

Experimental study on hydrodynamic dispersion of adsorption solute in saturated-unsaturated soil

ZHANG Fu-cang,KANG Shao-zhong,PAN Ying-hua
(Northwest Science & Technology University of Agriculture and Forestry)

Abstract: Experiments on hydrodynamic dispersion in saturated-unsaturated light loam and heavy loam soil are carried out. A method for calculation of definite hydrodynamic dispersion parameters for adsorption solute is deduced. According to the data of 1-D saturated dispersion experiment the saturated dynamic dispersion coefficient and retardation factor are obtained using simplified method.On the basis of theoretical analysis the formula for calculating the solute hydrodynamic dispersion of unsaturated soil is also attained.

Key words: adsorption solute; hydrodynamic dispersion coefficient; retardation factor

Optimal operation model for lagerge-scale water resources system having multiple resources and multiple users

HUANG Fang¹, XU Wen-bin², ZHENG Jian-qing³
(1.Zhejiang Design Institute of Water Conservancy & Hydropower;2.Zhejiang Provincial Bureau of Water Resources;
3.Wenzhou Municipal Bureau of Water Conservancy & Hydropower)

Abstract: A practical model namely distributive coefficient simulation model for optimization of large-scale water resources system having multiple resources and multiple users is proposed.It transforms the sequential decision making problem into the programming of restricted non-linear optimization.The model is applied to analyze the water supply system in Ningbao city having multiple water resources,multiple users and multiple steps of serial and parallel sub-system.The result is compared in contrast with that from mixed model including a simulation model and a multi-dimensional discrete differential dynamic programming model.

Key words: water resources system; simulation and distributive coefficient model