scholarly journals A monitoring model for the stress on a super-high arch dam during pre-impoundment construction

2020 ◽  
Vol 20 (8) ◽  
pp. 3604-3614
Author(s):  
Jingtai Niu ◽  
Xiang Luo ◽  
Zhiping Deng ◽  
Yang Zhang ◽  
Yingjia Guo ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
In Situ Stress ◽  
Arch Dam ◽  
Stress Monitoring ◽  
High Arch Dam ◽  
Factors Affecting ◽  
Arch Dams ◽  
Monitoring Model ◽  
Elastoplastic Constitutive Model ◽  
High Arch Dams

Abstract This paper presents a proposed model for monitoring the stress on a super-high arch dam during construction. Using mathematics, mechanics, and dam engineering principles, the mathematical expressions of the self-weight component of the dam prior to and following the sealing of the bottom of the arch were derived. The visco-elastoplastic constitutive model of dam concrete during construction was identified and used to develop a stress monitoring model for a super-high arch dam. Based on in-situ stress monitoring data collected during the construction of a super-high arch dam, the stress monitoring model was applied to a super-high arch dam accounting for future impoundment, and the key components of the monitoring model were isolated. The results show that the model has high fitting accuracy and incorporates an appropriate selection of factors affecting dam stress. The hydrograph of each component conforms to the structural characteristics of super-high arch dams during construction. This model overcomes the limitations of applying the complete self-weight of the dam body on the cantilever beam and was validated using data from a super-high arch dam construction project. Thus, this paper provides evidence for a safety monitoring model for super-high arch dams during construction.

Research Progress of Protected Plunge Pool of High Arch Dam

2014 ◽  
Vol 919-921 ◽  
pp. 1244-1247 ◽  
Author(s):  
Ying Kui Wang ◽  
Ren Qiang Liao
Keyword(s):  
Energy Dissipation ◽  
Southwest China ◽  
Arch Dam ◽  
Research Progress ◽  
Project Design ◽  
High Arch Dam ◽  
Arch Dams ◽  
Plunge Pool ◽  
Large Investment ◽  
High Arch Dams

The security researches of energy dissipation were always the focus in the High arch dams. Statistically, the trajectory type energy dissipation is the most widely used in the built high arch dams, and the protected plunge poor were always set downstream the dam body. However, the widely used protected plunge poor need large investment with the disadvantage of complicated operation and maintenance. Along with the construction of concrete high arch dam in the Southwest China, the “Reventment-Protected and Non-Bottom-Protected Plunge Pool” has been studied and proposed, which has the advantage of more simplified project design and more economy investment.

The Research on the Relation between Flexibility Coefficient and Buckling Stability of High Arch Dam

2012 ◽  
Vol 594-597 ◽  
pp. 1932-1935
Author(s):  
Hui Li ◽  
Zheng Zhong Wang ◽  
Xuan She
Keyword(s):  
Differential Method ◽  
Arch Dam ◽  
Present Condition ◽  
High Arch Dam ◽  
North West ◽  
Arch Dams ◽  
South West ◽  
Buckling Stability ◽  
Flexibility Coefficient ◽  
High Arch Dams

As a result of many high arch dams that are building and would be built in the south-west and north-west of China, arch dam is a kind of compressed thin buckle, not only effect by tension, but also by deformation. Thinner dam body with usage of increased levels of concrete and optimum designing, the local regions of high arch dams approach thin shell structure，which will lead to the structural buckling. Base on the above present condition, this paper would establish a series of generalized high and thin arch dam models whose height are 240m, and make theoretical analysis based on one of the crown- cantilever method- differential method for them, which attempts to provide a new method for the" critical flexibility coefficient ". At last, this paper would provide the relation between coefficient and buckling stability of high arch dam

Study of Risk Evaluation System of High Arch Dam Based on Failure Mechanism

2009 ◽  
Vol 417-418 ◽  
pp. 541-544
Author(s):  
Zai Tie Chen
Keyword(s):  
Risk Evaluation ◽  
Evaluation System ◽  
Failure Modes ◽  
Quantitative Estimation ◽  
Arch Dam ◽  
Dam Failure ◽  
High Arch Dam ◽  
Arch Dams ◽  
Risk Evaluation System ◽  
High Arch Dams

In view of the randomness in terms of high arch dam load, resistance and failure calamity loss as well as the fuzziness in terms of evaluation conclusion, a high arch dam risk evaluation system is established by means of risk analysis method. Natural factors, structural factors and human factors that lead to high arch dam failure are summed up on the basis of statistics. Through qualitative analysis coupled with quantitative estimation, it is determined that high arch dams generally involve five major failure modes: abutment rock mass destabilization, excess cracking, arch dam & dam foundation entire destabilization, extreme dam-overflow and destabilization of dam body along base plane. The state functions of individual major failure modes are established. An approach is made to the correlativity among the major failure modes and among the random variables within individual failure modes, and it is suggested that risk rate, economic loss risk value and life loss risk value should be used to assess the risk of high arch dams. A certain high arch dam abutment instability risk evaluation has been provided.

Risk-Based Research on Failure Mode of High-Arch Concrete Dam

2008 ◽  
Vol 385-387 ◽  
pp. 269-272 ◽  
Author(s):  
Zai Tie Chen
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Safety Evaluation ◽  
Arch Dam ◽  
State Function ◽  
High Arch Dam ◽  
Arch Dams ◽  
Disaster Loss ◽  
Explosion Load ◽  
High Arch Dams

Risk analysis can overcome the weakness of conventional safety evaluation of high-arch dams where the random nature of the load and resistance effect are ignored and the failure mode and failure disaster loss are not taken into account. On the basis of statistical analysis of the data of the failure arch dams and faulty and perilous arch dams in the world, it is deduced that the failure of high arch dam is mainly caused by super elevation floods, highly intense earthquakes, mountain landslides, abnormal temperature variation, explosion load, etc. Five major failure modes for high arch dams are suggested, namely dam abutment rock instability, fundamental plane instability, entire entity instability, excess cracking and extreme dam overflow. Based on the study of the failure mechanism of the major failure modes, a state function is established to calculate the failure probability of the major failure modes. An approach is developed to obtain the statistical quantity and the regularities of distribution of the load and resistance random variables.

scholarly journals Zoning Elastic Modulus Inversion for High Arch Dams Based on the PSOGSA-SVM Method

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Bo Chen ◽  
Xiao Fu ◽  
Xuyuan Guo ◽  
Chongshi Gu ◽  
Chenfei Shao ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Search Algorithm ◽  
Arch Dam ◽  
Support Vector ◽  
Inversion Method ◽  
Training Set ◽  
High Arch Dam ◽  
Arch Dams ◽  
Inversion Model ◽  
High Arch Dams

Real-time monitoring of the actual elastic modulus is essential and necessary to ensure the safe operation of arch dams. The zoning elastic modulus of a high arch dam is inversed by using deformation safety monitoring data in the operation period, based on the particle swarm optimization with gravitation search algorithm for support vector machine (PSOGSA-SVM) method. Firstly, the measured data of multipoints with a pendulum are separated to construct the initial sample training set; then, an optimal inversion model is established to reflect the complex nonlinear relationship between the mechanical parameters of the high arch dam and the deformation of measured points; finally, the PSOGSA-SVM method is used to train and dynamically update the training set so as to realize the optimization solution of the inversion model. The proposed inversion method is successfully applied to a high arch dam in China to verify its feasibility and validity. The results show that the actual elastic modulus of the dam body is much larger than the initial elastic modulus, which is beneficial to structural stability.

scholarly journals Deformation Monitoring of Geomechanical Model Test and Its Application in Overall Stability Analysis of a High Arch Dam

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Baoquan Yang ◽  
Lin Zhang ◽  
Enlong Liu ◽  
Jianhua Dong ◽  
Honghu Zhu ◽  
...  
Keyword(s):  
Model Test ◽  
Deformation Monitoring ◽  
Arch Dam ◽  
Test Method ◽  
Geomechanical Model ◽  
High Arch Dam ◽  
Arch Dams ◽  
Overall Stability ◽  
The Stability ◽  
High Arch Dams

Geomechanical model testing is an important method for studying the overall stability of high arch dams. The main task of a geomechanical model test is deformation monitoring. Currently, many types of deformation instruments are used for deformation monitoring of dam models, which provide valuable information on the deformation characteristics of the prototype dams. However, further investigation is required for assessing the overall stability of high arch dams through analyzing deformation monitoring data. First, a relationship for assessing the stability of dams is established based on the comprehensive model test method. Second, a stability evaluation system is presented based on the deformation monitoring data, together with the relationships between the deformation and overloading coefficient. Finally, the comprehensive model test method is applied to study the overall stability of the Jinping-I high arch dam. A three-dimensional destructive test of the geomechanical model dam is conducted under reinforced foundation conditions. The deformation characteristics and failure mechanisms of the dam abutments and foundation were investigated. The test results indicate that the stability safety factors of the dam abutments and foundation range from 5.2 to 6.0. These research results provide an important scientific insight into the design, construction, and operation stages of this project.

scholarly journals An EEMD-Based Denoising Method for Seismic Signal of High Arch Dam Combining Wavelet with Singular Spectrum Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Bo Li ◽  
Lixin Zhang ◽  
Qiling Zhang ◽  
Shengmei Yang
Keyword(s):  
High Frequency ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
Arch Dam ◽  
Seismic Signals ◽  
High Arch Dam ◽  
Denoising Method ◽  
Arch Dams ◽  
Frequency Components ◽  
High Arch Dams

Due to complicated noise interference, seismic signals of high arch dam are of nonstationarity and a low signal-to-noise ratio (SNR) during acquisition process. The traditional denoising method may have filtered effective seismic signals of high arch dams. A self-adaptive denoising method based on ensemble empirical mode decomposition (EEMD) combining wavelet threshold with singular spectrum analysis (SSA) is proposed in this paper. Based on the EEMD result for seismic signals of high arch dams, a continuous mean square error criterion is used to distinguish high-frequency and low-frequency components of the intrinsic mode functions (IMFs). Denoised high-frequency IMF using wavelet threshold is reconstructed with low-frequency components, and SSA is implemented for the reconstructed signal. Simulation signal denoising analysis indicates that the proposed method can significantly reduce mean square error under low SNR condition, and the overall denoising effect is superior to EEMD and EEMD-Wavelet threshold denoising algorithms. Denoising analysis of measured seismic signals of high arch dams shows that the performance of denoised seismic signals using EEMD-Wavelet-SSA is obviously improved, and natural frequencies of the high arch dams can be effectively identified.

scholarly journals Seismic Assessment of Arch Dams Using Fragility Curves

2015 ◽  
Vol 1 (2) ◽  
pp. 14-20 ◽  
Author(s):  
Vandad Kadkhodayan ◽  
S. Meisam Aghajanzadeh ◽  
Hasan Mirzabozorg
Keyword(s):  
Fragility Curves ◽  
Routine Data ◽  
Seismic Assessment ◽  
Arch Dam ◽  
The Other ◽  
Intensity Measure ◽  
Limit States ◽  
High Arch Dam ◽  
Arch Dams ◽  
Engineering Demand Parameter

In the present paper, the IDA approach is applied to analyzing a thin high arch dam. The parameters of Sa, PGA and PGV are used as intensity measure (IM) and the overstressed area (OSA) is utilized as engineering demand parameter (EDP) and then, three limit states are assigned to the considered structure using the IDA curves. Subsequently, fragility curves are calculated and it is showed that the PGA is a better parameter to be taken as IM. In addition, it is found that the utilizing the proposed methodology, quantifying the qualitative limit states is probable. At last, having the fragility curves and considering their slope in addition to the other routine data which can be extracted from these curves, one may be able to conclude that in what performance level the considered dam body seems to be weak and needs retrofitting works.

scholarly journals The Effect of Shear Sliding of Vertical Contraction Joints on Seismic Response of High Arch Dams with Fine Finite Element Model

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Shengshan Guo ◽  
Jianxin Liao ◽  
Hailong Huang ◽  
Hui Liang ◽  
Deyu Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Seismic Response ◽  
Element Model ◽  
Arch Dam ◽  
Slip Condition ◽  
Dead Load ◽  
High Arch Dam ◽  
Arch Dams ◽  
Contraction Joints

The contraction joints of arch dams with and without shear keys are simplified to be with no-slip condition and with relative sliding condition, respectively. Based on the Lagrange multiplier method, a contact model considering the manner of independent cantilever dead load type with no-slip condition and relative sliding condition is proposed to model the nonlinearities of vertical contraction joins, which is special to the nonlinear analysis of arch dams considering the manner of dead load type. Different from the conventional Gauss iterative method, the strategy of the alternating iterative solution of normal force and tangential force is employed. The parallelization based on overlapping domain decomposition method (ODDM) and explicit message passing using distributed memory parallel computers is employed to improve the computational efficiency. An existing high arch dam with fine finite element model is analyzed to investigate the effect of shear sliding of vertical joints on seismic response of the arch dam. The result shows that the values of maximum principal tensile stress under relative sliding condition are significantly greater than those under no-slip condition.

scholarly journals Nonlinear Response of High Arch Dams to Nonuniform Seismic Excitation Considering Joint Effects

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Masoomeh Akbari ◽  
Mohammad Amin Hariri-Ardebili ◽  
Hasan Mirzabozorg
Keyword(s):  
Structural Response ◽  
Incompressible Material ◽  
Arch Dam ◽  
High Arch Dam ◽  
Arch Dams ◽  
Base Level ◽  
Nonlinear Responses ◽  
Wave Passage ◽  
Spatially Varying Ground Motions ◽  
Spatially Varying

Nonuniform excitation due to spatially varying ground motions on nonlinear responses of concrete arch dams is investigated. A high arch dam was selected as numerical example, reservoir was modelled as incompressible material, foundation was assumed as mass-less medium, and all contraction and peripheral joints were modelled considering the ability of opening/closing. This study used Monte-Carlo simulation approach for generating spatially nonuniform ground motion. In this approach, random seismic characteristics due to incoherence and wave passage effects were investigated and finally their effects on structural response were compared with uniform excitation at design base level earthquake. Based on the results, nonuniform input leads to some differences than uniform input. Moreover using nonuniform excitation increase, stresses on dam body.

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