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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.

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.

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.

Cao X.,Wuhan University | Cao X.,Huaneng Lancang River Hydropower Co. | He Y.,Wuhan University | Feng R.,Wuhan University | And 2 more authors.
Journal of Hohai University | Year: 2013

The influence of the downstream turning point on the seismic performance of a gravity dam was studied through earthquake projects and finite element calculation. The results show that a position of the downstream turning point that was too low had adverse effects on the seismic performance of the gravity dam. The stress of the neck of the dam increased with the descending position of the downstream turning point and the ascending height of the dam. To ensure good seismic performance of the dam, the position of the downstream turning point should not be too low in project design; it should not be lower than 20% of the height of the dam for a 100 m-high gravity dam in areas with an earthquake intensity of eight or an even higher degree. Linear elastic and nonlinear dynamic finite element analysis were conducted for a practical project in a hydropower station in Yunnan Province. The calculation results show that, under the design earthquake effects, obvious stress concentration and cracks appeared in the neck of the dam. When the earthquake overload coefficient was 1.17, the upstream cracks joined the downstream cracks in the neck of the dam, indicating that the seismic performance of the dam was very poor. The downstream turning point should be reasonably improved in project design.

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.

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