He J.,Wuhan University |
Gao Q.,Wuhan University |
Gao Q.,National Dam Safety Research Center |
Shi Y.,Wuhan University
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2016
Dam safety evaluation is a complicated and comprehensive evaluation problem involving multiple factors, multiple hierarchies and compound uncertainties. Through the introduction of the cloud model theory specialized in uncertainty problems into dam safety evaluation, the paper makes a research on the ubiquitous uncertainties of dam safety monitoring data, and proposes a multi-hierarchical comprehensive evaluation method for dam safety based on cloud model. By using a group of random numbers with stable tendencies to replace definite fuzzy degrees of membership and utilizing cloud generators to create membership clouds, the approach obtains a comprehensive dam safety evaluation result characterized by numerical features of cloud model and considering uncertainty of monitoring data. It not only gives a reasonable assessment to the state of dam safety, but also shows the credibility of this evaluation result and instabilities for the result created by uncertainties. Compared with the traditional fuzzy synthetic evaluation approach, examples show that the comprehensive dam safety evaluation method based on cloud model proposed in the paper is reasonable, feasible and superior. © 2016, Editorial Board of Journal of Systems Engineering Society of China. All right reserved.
Niu X.,Changjiang Institute of Survey Planning Design and Research |
Niu X.,National Dam Safety Research Center
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2017
Achievements in construction of concrete face rockfill dams (CFRDs) is remarkable in China, particularly in rapid development and large quantities of high dams. But certain dangerous situations have appeared with these dams: serious seepage, structural crack, vertical joint extrusion damage, etc., especially with high dams. This paper sums up the current situations of this type and challenges to the design and construction of high CFRDs, and identifies technical problems in the existing design theory, analysis method and technical standard. Our analysis reveals three major problems: insufficient research on design theory, low accuracy in analysis method, and lack of good integrity in technical standard. Therefore, we suggest a new design concept of high CFRDs that focuses on face panel reliability and considers four aspects: control of dam deformation, durability of the panels, adaptive capability of the panels, and repairing of dam body. © 2017 All right reserved.
Liu J.-L.,GD Yue Gang Water Supply Co. |
He Y.-L.,Wuhan University |
Xiong K.,Changjiang Institute of Survey Planning Design and Research |
Xiong K.,National Dam Safety Research Center |
Li J.-C.,Chengdu Hydroelectric Investigation And Design Institute
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2013
Hardfill material is a new material with low strength in which the granular materials are solidified with some cementing material. The nature of the special material is between RCC and soil, which has typical features as elastic-plastic material in its stress-strain relations and obvious behavior of strain softening. On the summary of the early researches, a non-linear elasticity constitutive model for Hardfill material was put forth. The constitutive model can indicate the strain softening behavior accurately and all of the six parameters have specific physical interpretation and can be determined by material uniaxial and triaxial test using the given solution procedure. The verified constitutive model was applied to the Oyuk dam, a typical Hardfill dam at 100 m level. The results show that the distribution of the stress and deformation is mainly accordant in both the non-linear and linear elastic calculation, and there is little difference because of the low stress level. However, the stress is obviously smaller in the non-linear calculation than the linear elastic result in the high stress level at the toe of the dam.
Su P.,Changjiang Institute of Survey Planning Design and Research |
Su P.,National Dam Safety Research Center |
Weng Y.,Changjiang Institute of Survey Planning Design and Research |
Weng Y.,National Dam Safety Research Center |
And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2014
The lift joint segments which distribute in the roller compacted concrete(RCC) are difficult to be simulated in the temperature field analysis. Based on the principle of composite element method(CEM), the composite element model for temperature field of RCC is built. The preprocessor is simple and convenient and the lift joint segments are contained in the composite elements, thus the mesh generation of lift joint can be considerably simplified. The quantity of mesh can be easily controlled and the shape of mesh can be improved. The composite elements may contain sub-elements of arbitrary shape whose temperature can be interpolated from their corresponding mapped nodal temperatures. The temperatures in lift joint segments are calculated from mapped nodal temperatures of their neighboring sub-elements. In composite element method, the solving procedure of the mapped nodal temperatures is similar to that in conventional finite element method, and the elements containing no lift joint are degenerated to conventional finite elements automatically. The programs for composite element algorithm can be incorporated into the conventional finite element analysis procedure with intrinsic coherence. The comparative study between the composite element method and the conventional finite element method has been illustrated to verify the composite element algorithm for temperature of RCC.
Yan Q.,National Dam Safety Research Center |
Gao Z.H.,China Three Gorges University |
Song Z.C.,China Three Gorges University
Applied Mechanics and Materials | Year: 2014
Sensitivity analysis of model parameters is a rock fill parametric inversion analysis method to determine the unknown parameters. Traditional sensitivity analysis is basically a lot of trial or the method of single factor analysis based on a large amount of calculation, but, unable to reflect the real situation. The method of particle swarm optimization based on neural network based nonlinear mapping relationship between model parameters and displacement to finite elementsimulation of dam deformation. Basing on the orthogonal design, the methods of range analysis and variance analysis method were used for sensitivity analysis of the parameters of Duncan E-B model and the impact of various parameters on the dam displacement, and then it can be as the parameters of rock fill dam provide basis for determining the unknown parameters inversion. © (2014) Trans Tech Publications, Switzerland.
Zhang C.H.,Chang Jiang Survey Planning Design and Research LLC |
Zhang C.H.,National Dam Safety Research Center |
Zhou S.D.,Chang Jiang Survey Planning Design and Research LLC |
Zhou S.D.,National Dam Safety Research Center |
And 3 more authors.
Applied Mechanics and Materials | Year: 2014
Considering topographic and geologic conditions, project layout and investments, concret arch dam is adopted in a hydropower plant and underground powerhouses are arranged in mountains on left and right banks. However, the minimum distance between the excavation boundary of abutment of arch dam on elevation 850m and underground powerhouse is only 110m. Abutment load created by reservoir storage, permeability and earthquake may affect general stability of underground caverns in operation period. Thus, using elasto-plastic finite difference method, three dimensional numerical simulation models of underground caverns and slope of abutment of arch dam is establised and proposed key issues are systemly studied. The calculation results show that, under reservoir storage and dam vibration subject to earthquke, abutment load has small effect on plastic zone, displacement and stress around opennings and the caverns would be stable in operation period. © (2014) Trans Tech Publications, Switzerland.
Wang J.,Hohai University |
Wang J.,National Dam Safety Research Center |
Qiao Q.,Hohai University |
Qiao Q.,National Dam Safety Research Center |
Leng F.,Hohai University
Applied Mechanics and Materials | Year: 2013
It is one of the most important issues for finite element analysis of lining structures that how to describe anchor rod reasonably and effectively and simulate the interaction between rod and concrete or rock. Virtual nodes are constructed in concrete/rock element at the ends of anchor rod and bond-slip element is set between virtual nodes and beam element which describes anchor rod. An embedded combined element with bond slip and shear deformation is established through the transformation of nodal force at nodes of bond-slip element to those of concrete/rock element via shape functions. The element is convenient for meshing element because the location and direction of anchor rod are not necessary to be considered. Meanwhile, the element has the advantage of low computing cost. Finally, the validity and efficiency are verified by numerical examples. © (2013) Trans Tech Publications, Switzerland.
Su P.F.,Changjiang Institute of Survey Planning Design and Research |
Su P.F.,National Dam Safety Research Center |
Lu X.L.,CAS Wuhan Institute of Rock and Soil Mechanics
Applied Mechanics and Materials | Year: 2013
In order to analysis thermal stress of mass concrete accurately, material properties of mass concrete are studied by numerical simulation method, and the equivalent age is introduced to describe the mechanical properties of concrete. The calculation models of concrete mechanical parameters are summarized, and then the calculation procedures are established on the basis of equivalent age. In this way, the temperature and temperature history are considered in these models. Meanwhile, the governing equation and computer program of the thermal stress based on the equivalent age are developed. The comparison of the numerical example using proposed method and conventional FEM method shows that the proposed method performs more adaptable and accurate. © (2013) Trans Tech Publications, Switzerland.
Niu X.,Changjiang Survey Planning Design and Research Co. |
Shi H.,Changjiang Survey Planning Design and Research Co. |
Shi H.,National Dam Safety Research Center |
Li H.,Changjiang Survey Planning Design and Research Co. |
And 4 more authors.
Hedongli Gongcheng/Nuclear Power Engineering | Year: 2016
The influencing factors of radioactive waste water underground migration are analyzed, the radioactive waste water migration protection conditions of underground and ground nuclear power plant is contrasted, and the ideas and specific engineering protection measures for radioactive waste migration protection of underground nuclear power plant are systematic proposed, that is, all radioactive waste water security measures of ground nuclear power plants are completely preserved and make full use of the natural protective properties of the rock, the additional closed, dewatering and other reliable engineering measures are set in the surrounding rock mass, the migration channel of radioactive waste water is blocked, at the same time, the collection, disposal and monitoring system are also set. The effect of above protective measures is remarkable by numerical analysis, and the produced radioactive waste water of underground nuclear power plant is controlled in severe accident condition. © 2016, Editorial Board of Journal of Nuclear Power Engineering. All right reserved.
Leng F.,Hohai University |
Leng F.,National Dam Safety Research Center |
Wu G.,Jiangsu Provincial Communications Planning and Design Institute
European Journal of Environmental and Civil Engineering | Year: 2013
A thermodynamics-based damage constitutive model is developed for concrete, which describes tensile and compressive damage well and follows the second thermodynamic law. Constitutive model should meet general thermodynamics, while it describes behaviour characteristic of concrete material, which are often not able to be satisfied by existing models because of various of hypotheses. Generalised stress functions and dissipative generalised stress functions are constructed from free energy function and energy dissipation function according to the physical meaning of the thermodynamic potential and the characteristic of the constitutive model of concrete. Then, a damage constitutive model of concrete is developed and the parameters of the model are identified. The numerical method of the model is also presented. The model in the paper can satisfy the second thermodynamic law automatically and simulate the tensile and compressive behaviour of concrete well. Finally, the feasibility and practicality of the model is verified by the analysis of classical experiments and Koyna dam. © 2013 Taylor and Francis.