Abstract: The concepts of grey probability, grey probability distribution, grey probability density, grey expectation and grey variance are defined based on the theory of probability and grey system approach. The method of grey-stochastic risk for system risk analysis is established. In this method, the uncertainty of system risk is attributed to grey uncertainty of system, the variables of system performance function are treated with grey probability distributions and the system hazard is quantified with grey-stochastic risk. The grey-stochastic risk can be transformed into ordinary stochastic risk and computed using advanced first-order second-moment method. An example of application is given.
Key words: risk analysis; grey uncertainty; grey probability; grey probability distribution; grey-stochastic risk
Abstract: The significant imbalance between demand and available supply of water in different regions of China leads to the requirements of water transfer. Three questions always occur:whether the transfer is necessary or not, how much water should be transferred and how to distribute the water. Keeping enough amount of water for people's living, ecological use and least production the decision making is always based on the economic objectives including yearly profit, period of investment regain. To this end, a series of model for optimizing the space and temporal distribution of water resources and allocation of different sectors are proposed. Four types of economic objectives, 7 combinations of different variables and 6 types of marginal benefit for water resources utility are considered. Consequently, 168 types of optimization are formed, which correspond to different problems in practical use. As examples, some analytic solutions are given.
Key words: Water transfer; distribution of water resources; optimization; economic objectives; model; analytical soulution
Abstract: Based on the elastic-plastic increment theory the bearing capacity of concrete gravity dam is studied using stability and analytic method expressed in strain space. Criterion for stability of concrete gravity dam and foundation rock system is proposed. Two kinds of material strength margin are considered in the study. This analytical method is able to reflect the physical mechanism of concrete gravity dam system if unstable state is occurred due to damage or softening of concrete and rock. The calculation result indicates that the method is rational and feasible.
Key words: concrete; gravity dam; stability; bearing capacity
Abstract: The leaching losses of indigenous and applied nitrate-nitrogen were monitored using non-weighting lysimeter in a field of loamy sandy soil under the condition of infiltration and redistribution.Ponded irrigation was treated as a pulse input to the soil volume within which an operational defined transport volume Vst exists.Within Vst nitrogenous fertilizer could experience various physical,chemical and biological reaction on its passage to the drains.The transfer function model developed by Jury etual and white was applied to simulate nitrate-nitrogen transport through the unsaturated soil under unsteady flow.The probability density functions of the travel time of the nitrate-nitrogen transport under the experimental condition were determined from the normalized rates of loss of nitrate-nitrogen mass to the drains.The parameters including the median and the mean travel time,fractional transport volume were calculated.Furthermore,the dynamics of nitrate-nitrogen concentration in the effluent and the cumulative quantity of nitrate-nitrogen leached during the experiment were estimated using the equations proposed by White.The predicted result is in good agreement with observation data.
Key words: unsaturated soil;nitrate-nitrogen;leaching;transport volume;transfer function model;stochastic simulation
Abstract: Two kinds of load combination model are proposed for different situations of external water and soil pressure. In the mean time three joint interaction models corresponding to different forms of joint between primary and secondary linings are suggested. Programs for FEM to calculate the stress of the linings are coded. The calculation results show that the assumption of secondary lining solely bearing the total water and soil pressure is not correct and may induce unsafe errors in lining design. It is recommended that the commended that the coupling bwtween primary and secondary linings must be reinforced forming an integrated structure to bear the external pressure.
Key words: shield pressure tunnel; secondary lining; interaction model of joint; FEM analysis
Key words: concrete; crack; fracture parameter; photoelastic coating
Abstract: The discontinuous deformation computational mechanics model for interaction analysis of multi-body system is developed.By using this model the transfer of interface interaction force and discontinuous deformation status of interface during loading can be accurately simulated.This method is applied to evaluate the stress and deformation of the concrete gravity dam with multiple vertical joints under static load.Numerical computational results of a dam including the normal and shear stresses along the vertical joints and dam-foundation interface are given for illustration.It is shown that the model is feasible for the behavior prediction of multi-body system with mutuple interfaces and joints of differentmaterials.
Key words: gravity dam; interfaces; contact stress; blocking of concrete dam; finite elements discontinuous deformation; computational mechanics; joints
Abstract: A statistical downscaling approach,including a stochastic weather generator and a downscaling technique,is developed to transfer daily rainfall in general circulation model (GCM) grid to local area.To analyze its reasonability,an area with grid of 2.5°in latitude and 3.75° in longitude in Guangdong Province is selected and daily precipitation series of 32 years in 7 stations are used.The statistical characteristics of daily precipitation series generated by the weather generator are compared with the observation data recorded both in local and grid scale.Based on the assumption of the future changed climate precipitation series from one set of history records, verification of the downscaling technique is also made by comparing the statistical characteristics as well as monthly and amount from downscaling way with those from assumed precipitation series.
Key words: general circulation model; stochastic weather generator; downscaling
Abstract: A new method for generating contours in rater graphics is presented in this paper.The method is based on the principle of connecting the pels with the same value in the graphics constructed by computer,which is composed of discrete points.No grid searching and swinging of isoline is needed.The calculation program for this method is simple and the map constructed possesses high precision.An example of applications is given.
Key words: raster graphics;interpolation;contour;influent domain,set of influent points;algorithm
Abstract：The integral equation is used to solve the problem of single pile in layered saturated soil considering the consolidation and rheology. Based on the fundamental solution of circular load in the interior of the layered half space, the second kind of Fredholm integral equation of the single pile in layered saturated viscoelastic soil is obtained. The integral equation can be simplified by means of Laplace transform. Furthermore, by using the corresponding inverse Laplace integral transform and numerical solution of integral equation, the displacement and axial force as well as the shear stress of the pile are obtained.
Key words：pile；layered soil; consolidation; integral equation; propagator matrix
Abstract: The comprehensive FEM analysis for the Shimen arch dam and its abutment is carried out as an example to demonstrate the proposed method utilizing the monitoring data for calculation.Based on teh back analysis of permeability coefficient and tensile strength of the seam between dam and foundation,the 3-D seepage flow and elastoplastic FEM analysis of arch dam and its abutment are conducted.The safety factor against sliding of arch dam is determined using some different methods to verify the stability of the dam.
Key words: arch dam; foundation; monitoring data; comprehensive analysis
Abstract：Based on Fenves' 3 D joint element model, a non linear analysis of the Xiaowan arch dam, having contraction joints, under the design earthquake is carried out. The convergence due to mesh size, interval and number of joints as well as the effect of grouting strength and reservoir levels are investigated in detail. There are 25 contraction joints with real interval being simulated. It is found that the Fenves's conclusion that simulation for 3 joints is enough for nonlinear analysis of arch dam is valid only for the stress result. In order to find out the reasonable joint opening at the important position of the dam, the simulation of sufficient number of contraction joints with real interval is necessary. Moreover, the reservoir level is having obvious effect on the nonlinear response of the dam.
Key words：arch dam；non linearity; contraction joints; seismic analysis
Abstract：Theoretical analysis and experimental data show that to increase the retrogressive erosion of the upstream river section and decrease the back deposition of the dredged channel are important to elevate the effect of deposition reduction in dredging.On this basis,the designed slope of the dredged channel must be large enough to overcome the friction and keeping the sediment transport capacity not to change.According to the data analysis,the critical slope is about 1%00
Key words：shriveling channel; deposition reduction; river dredging; critical slope
Abstract：Based upon the principle of least resistance,the stream passing around the Jiuduan sandbank is studied theoretically and the formula for predicting the development of the bank is derived.By using this formula,the evolution process of related river section is further analyzed.The calculation method is applied to predict the flow ratios between two branches around the sandbank is different stages of river regulation work and its validity is verified by the data of flow measurement.
Key words：Yangtze River estuary; river regulation; stream passing around sandbank; principle of least resistance
Abstract: On the basis of general principles of mechanics and critical state soil mechanics theory,a theoretical formula determining the coefficient of earth pressure at rest for cohesionless soil is derived by means of combining hypoplasticity with critical state soil mechanics.The formula has a simple form and is only related to the effective angle of internal friction of soil.There is a slight difference between the calculated value of the formula and that of other formulae.The further investigation of the formula shows that it can be used to determine the coefficient of earth pressure at rest of cohesionless soil.
Key words: hypoplasticity;critical state soil mechanics;cohesionless soil; coeffcient of earth pressure at rest
Abstract: Based on the dynamic response model of crop to water salinity,the relation between crop growing and soil salt movement is analyzed.The optimal design model of irrigation schedule for high yield,water saving and salinity control is proposed.It helps to promote the management of water saving and utilization of poor quality water.Case study shows that the model is reasonable and practical,the percentage of fresh water saved is 31.1% and the crop yield is optimized.
Key words: water saving; salinity control;salt water;irrigation schedule;optimal design model