Catastrophic Analysis of Seismic Response of Gravity Dam Sliding along Base Surface

2011 ◽  
Vol 311-313 ◽  
pp. 2164-2168
Author(s):  
Dun Ben Sun ◽  
Qing Wen Ren
Keyword(s):  
Weibull Model ◽  
Gravity Dam ◽  
Stable Region ◽  
Instability Mechanism ◽  
Gravity Dams ◽  
Base Surface ◽  
Instability Problem ◽  
Nonlinear Constitutive Model ◽  
Hysteresis Phenomena ◽  
Sliding Instability

For the instability problem of gravity dam sliding along base surface, cubic nonlinear constitutive model of soft material in base surface is adopted, which is usually expressed by Weibull model. Dynamic Equations of dam sliding along base surface is established. By means of catastrophe theory, the jumping and hysteresis phenomena of the vibration amplitude of the dam is analyzed, the parameter range of stable region in which amplitude doesn’t happen catastrophe is given and the factors which cause amplitude instability are discussed. The results obtained in the paper are of significant value for understanding the sliding instability mechanism of gravity dam under earthquake, as well as guiding the design of gravity dams.

scholarly journals Updated Kriging-Assisted Shape Optimization of a Gravity Dam

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 87
Author(s):  
Yongqiang Wang ◽  
Ye Liu ◽  
Xiaoyi Ma
Keyword(s):  
Surrogate Model ◽  
Computational Cost ◽  
Region Of Interest ◽  
Optimization Procedure ◽  
Optimal Shape ◽  
Small Sample ◽  
Gravity Dam ◽  
Kriging Surrogate Model ◽  
Gravity Dams ◽  
Sample Set

The numerical simulation of the optimal design of gravity dams is computationally expensive. Therefore, a new optimization procedure is presented in this study to reduce the computational cost for determining the optimal shape of a gravity dam. Optimization was performed using a combination of the genetic algorithm (GA) and an updated Kriging surrogate model (UKSM). First, a Kriging surrogate model (KSM) was constructed with a small sample set. Second, the minimizing the predictor strategy was used to add samples in the region of interest to update the KSM in each updating cycle until the optimization process converged. Third, an existing gravity dam was used to demonstrate the effectiveness of the GA–UKSM. The solution obtained with the GA–UKSM was compared with that obtained using the GA–KSM. The results revealed that the GA–UKSM required only 7.53% of the total number of numerical simulations required by the GA–KSM to achieve similar optimization results. Thus, the GA–UKSM can significantly improve the computational efficiency. The method adopted in this study can be used as a reference for the optimization of the design of gravity dams.

Genetic Algorithm for Searching for Critical Slip Surface in Gravity Dams Based on Stress Fields

2013 ◽  
Vol 790 ◽  
pp. 146-149
Author(s):  
Jian Yun Chen ◽  
Shu Wang ◽  
Qiang Xu ◽  
Jing Li
Keyword(s):  
Genetic Algorithm ◽  
Slip Surface ◽  
Safety Evaluation ◽  
Fem Analysis ◽  
Stress Fields ◽  
Gravity Dam ◽  
Critical Slip Surface ◽  
Gravity Dams ◽  
Sliding Stability ◽  
Search Program

Currently, the safety evaluation of gravity dam concentrates on stress and anti-sliding stability of the dam. A lot of research shows that the upper area of the dam is one of the whole dams weakest areas during an earthquake and should be studied in details. In this study, the genetic algorithm and non-linear FEM analysis are combined, then a search program is written to search the critical slip surface in the dams upper area. Finally, the surface which has the least anti-sliding stability coefficient is obtained, the most dangerous slip surface and its anti-sliding coefficient as well as the corresponding time are acquired to evaluate the safety of the dam.

Study on System of Gravity Dams Aided Design

2011 ◽  
Vol 255-260 ◽  
pp. 3584-3588
Author(s):  
Zhi Yuan Hou ◽  
Bin Tian ◽  
Ze Yun Xiao
Keyword(s):  
Gravity Dam ◽  
Design System ◽  
Structure Modeling ◽  
Geological Modeling ◽  
Gravity Dams ◽  
Element Analysis ◽  
3D Finite Element ◽  
3D Geological Modeling ◽  
Aided Design ◽  
Analysis Stability

Since there are some characteristics such as correlation, repeatability and integrity during the gravity dam design process, an automatic gravity dam assistant design system was established by adopting C sharp programming language, Visual Studio Development Suite as well as material mechanics and Technology of Parametric Drawing. The System includes four modules: 3D geological modeling, gravity dam structure modeling, dam sections analysis and database management. These modules realized different specialty cooperation and offered many-side analysis such as: 3D finite element analysis, stability analysis, stress analysis, section optimization and report export.

Random Response Spectrum Analysis of Gravity Dam Classes: Simplified, Practical, and Fast Approach

2018 ◽  
Vol 34 (2) ◽  
pp. 941-975 ◽  
Author(s):  
Mohammad Amin Hariri-Ardebili ◽  
Victor E. Saouma
Keyword(s):  
Fragility Curves ◽  
Response Spectrum ◽  
Input Parameter ◽  
Gravity Dam ◽  
Random Response ◽  
Numerical Techniques ◽  
Gravity Dams ◽  
Response Spectrum Analysis ◽  
Fast Approach ◽  
Demand And Capacity

The seismic risk of concrete dams may be assessed using various numerical techniques, ranging from simplified methods to linear and nonlinear ones. Such methods should be combined with probabilistic concepts to account for the randomness in both demand and capacity. This paper proposes a random version of a simplified response spectrum method (involving equivalent static lateral forces [ESLFs]) for gravity dams by means of propagating uncertainties through the input parameters. Input parameter sensitivity is quantified and the extended procedure is explained step by step. Results are then generalized for the different dam classes. The impacts of sampling size and technique (i.e., pseudo-random and quasi-random) are also discussed. A time-based performance is evaluated and fragility curves are derived. This method may be used during the initial stages of a design process or safety analysis for existing dams.

scholarly journals Research and Application of a Seismic Damage Classification Method of Concrete Gravity Dams Using Displacement in the Crest

2020 ◽  
Vol 10 (12) ◽  
pp. 4134
Author(s):  
Xiang Lu ◽  
Liang Pei ◽  
Jiankang Chen ◽  
Zhenyu Wu ◽  
Chen Chen
Keyword(s):  
Failure Modes ◽  
Seismic Damage ◽  
Classification Method ◽  
Gravity Dam ◽  
Concrete Gravity Dam ◽  
Gravity Dams ◽  
Damage Classification ◽  
Residual Displacement ◽  
Concrete Gravity Dams ◽  
Damage Coefficient

Concrete gravity dams are one of the most common water retention structures, some of which are located in seismically active regions. Determination of damage level after earthquakes plays an important role in assessing the safety behavior of concrete dams. Compared with the traditional performance parameters obtained from numerical simulations, such as the damage coefficient, energy dissipation, failure modes, and stress state, etc., the displacement of dams can be acquired from daily monitoring data conveniently and quickly. It is of great significance for the rapid and effective evaluation of dam properties after earthquakes. The residual displacement in the concrete gravity dam crest was adopted as the performance parameter in the paper, and the linear mapping function between the residual displacement and the damage coefficient was established based on the concrete damaged plasticity model (CDP). Based on the traditional classification method with damage coefficient, a residual displacement-based seismic damage classification method with corresponding level limits was proposed. The seismic fragility analysis of Guandi concrete gravity dam was conducted as an example to illustrate the presented methodology. The results indicate that the proposed method is reasonable, effective, and can be easily applied to different projects after slight modifications.

FAILURE PATTERNS OF SHEAR KEYS AND SEISMIC RESISTANCE OF A GRAVITY DAM WITH LONGITUDINAL JOINTS

2014 ◽  
Vol 08 (01) ◽  
pp. 1450004 ◽  
Author(s):  
LIAOJUN ZHANG ◽  
HANYUN ZHANG ◽  
SHAOWEI HU
Keyword(s):  
Time History ◽  
Gravity Dam ◽  
Seismic Resistance ◽  
Size Difference ◽  
Crack Model ◽  
Gravity Dams ◽  
Dam Foundation ◽  
Failure Patterns ◽  
Shear Keys ◽  
Longitudinal Joints

In order to thoroughly study the seismic resistance of gravity dams with longitudinal joints, a contact model based on constraint function method is used to simulate the shear keys within the joints and a concrete smeared crack model is selected to present the cracking characteristics of concrete materials. Because of the great size difference between the shear keys and the dam body, a glue mesh is proposed to implement multi-scale modeling. A dam-foundation-reservoir interaction system with longitudinal joints considering the various shear keys is developed and analyzed by nonlinear time-history method. On the basis of actual construction, arrangement and loading features of shear keys, a gravity dam is taken as a test case and a finite element model of the dam is established with triangular or trapezoidal shear keys. The working behaviors and failure patterns of various shear keys under earthquakes are explored. Moreover, the effects of various shear keys on the seismic resistance of the gravity dam are discussed. The results show that the seismic responses of shear keys are resulted in designed forms. The occlusion and dislocation of the shear keys within the longitudinal joints have an impact on seismic resistance of the gravity dams.

scholarly journals Safety Monitoring Index of High Concrete Gravity Dam Based on Failure Mechanism of Instability

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Shaowei Wang ◽  
Chongshi Gu ◽  
Tengfei Bao
Keyword(s):  
Failure Mechanism ◽  
Failure Modes ◽  
Extreme Values ◽  
Safety Monitoring ◽  
Gravity Dam ◽  
Material Strength ◽  
Observation Data ◽  
Gravity Dams ◽  
Concrete Gravity Dams ◽  
Monitoring Index

Traditional methods of establishing dam safety monitoring index are mostly based on the observation data. According to the performance of dam-foundation system under the experienced loads, alarm values and extreme values are predicted for monitoring quantities. As for some dams, the potential most unfavorable loads may not yet have appeared, and dam bearing capacity may also decrease over time. Therefore, monitoring index determined by these methods can not reflect whether the dam will break or not. Based on the finite element method, to study the progressive instability failures of high concrete gravity dams under the failure modes of material strength degradation or uncertainty and extreme environmental loads during operation, methods of strength reduction and overloading are, respectively, used. Typical stages in the instability processes are identified by evaluation indicators of dam displacement, the connectivity of yield zones, and the yield volume ratio of dam concretes; then instability safety monitoring indexes are hierarchically determined according to these typical symptoms. At last, a case study is performed to give a more detailed introduction about the process of establishing safety monitoring index for high concrete gravity dams based on the failure mechanism of instability, and three grades of monitoring index related to different safety situations are established for this gravity dam.

scholarly journals The Failure Mechanism of Concrete Gravity Dams considering Different Nonlinear Models under Strong Earthquakes

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Chunli Yan ◽  
Jin Tu ◽  
Deyu Li ◽  
Shengshan Guo ◽  
Hui Liang
Keyword(s):  
Nonlinear Models ◽  
Failure Process ◽  
Damage Model ◽  
Dynamic Contact ◽  
Gravity Dam ◽  
Concrete Gravity Dam ◽  
Seismic Capacity ◽  
Gravity Dams ◽  
Strong Earthquakes ◽  
Concrete Gravity Dams

The paper focuses on the failure process and mechanism of the concrete gravity dam considering different nonlinear models under strong earthquakes. By taking a typical monolith of a concrete gravity dam as a case study, a comparative analysis of the failure process and mechanism of the dam considering the plastic damage model and the dynamic contact model, respectively, is performed using the seismic overload method. Moreover, the ultimate seismic capacity of the dam is evaluated for both of the nonlinear models. It is found that the ultimate seismic capacity of the dam is slightly different, but the failure process has significant distinctions in each model. And, the damage model is recommended when the conditions permit.

scholarly journals Numerical Simulation of Shock Response and Dynamic Fracture of a Concrete Dam Subjected to Impact Load

2016 ◽  
Vol 20 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Lu Lu ◽  
Xin Li ◽  
Jing Zhou ◽  
Genda Chen ◽  
Dong Yun
Keyword(s):  
Dynamic Fracture ◽  
Impact Load ◽  
Failure Process ◽  
Gravity Dam ◽  
Strong Impact ◽  
Concrete Gravity Dam ◽  
Gravity Dams ◽  
Concrete Gravity Dams ◽  
Shock Response ◽  
The Impact

<p>The shock response and dynamic fracture of concrete gravity dams under impact load are the key problems to evaluate the antiknock safety of the dam. This study aims at understanding the effects of impact shock on the elastic response and dynamic fracture of concrete gravity dams. Firstly, this paper uses acceleration records of a concrete gravity dam under impact to establish the correct way to determine the concrete gravity dam of the fundamental frequency and present cut sheets multi-degree-of-freedom dynamic modeling. Under strong impact loading, the constitutive relation of concrete gravity dam and the highest frequency of the impact are uncertain. So, the main advantage of this method is avoiding the use of elastic modulus in the calculation. The result indicates that the calculation method is a reliable computational method for concrete gravity dams subjected to impact. Subsequently, the failure process of dam models was numerically simulated based on ABAQUS commercial codes. Finally, this paper puts forward suggestions for future research based on the results of the analysis.</p>

Numerical Research on the Gravity Dam Deep Anti-Sliding with Engineering Mechanics Based on Damage Theory

2014 ◽  
Vol 910 ◽  
pp. 289-296
Author(s):  
Shuang Liu ◽  
Qing Wen Ren ◽  
Chen Lu Zhou
Keyword(s):  
Rock Mass ◽  
Numerical Model ◽  
Damage Mechanics ◽  
Failure Process ◽  
Gravity Dam ◽  
Instability Criterion ◽  
Gravity Dams ◽  
Dam Foundation ◽  
Sliding Stability ◽  
Foundation Rock

Currently, researches on the gravity dam deep and shallow anti-sliding stability mainly focus on the analysis method and instability criterion, while the studies on specifically test the breakage of gravity dams due to weakening foundation rock mass and structural planes under loading are rare. Based on damage mechanics theory, this paper established a numerical model that analyzed the damage failure process of dam foundation rock mass. Taking two typical gravity dam models as the study objects, the damage processes of the dam foundations were simulated dynamically. Additionally, a comparison with other two traditional methods further validated the correctness and feasibility of the numerical model. In sum, the study findings point out that the numerical model is not only applicable to the study of the breakage mechanism of dam foundation rock mass, but also can be used as a new method to analyze problems related to deep anti-sliding stability of gravity dams.

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