Dam Deformation Research Articles

Dynamic approachs for system identification applied to deformation study of the dams

To dynamical study of the dams, the prediction of occurred deformation caused by hydrostatic and hydrodynamic pressures during the operation phase as well as the designing phase is necessary. The reservoir water changes also the permanent variations of atmospheric temperature especially in the areas where there are significant seasonal and circadian changes in conditions are important factors to “dynamic system” of the dams. The aim of this paper is to present an applied dynamic method to identify the body of the dam as a dynamic system and to predict its behavior in the variable environmental conditions based on the monitoring observations. Non-parametric methods such as cross-covariance and coherence method are applied for system identification of the dam based on time series of input signal of measured forces and output signal of deformation measurements. The main feature of this paper is using the weighting function method which enables “System Identification” of the dam as a dynamic system, to model the deformation of the dam. The applied weighting function method benefits from measurements of effective factors on system of the dam also the deformation monitoring measurements from different sensors. For practical applicability of the method for a dam, Masjed–Soleiman “earth–dam” in Iran has been chosen. A wide range of instruments has been installed inside the dam to control the deformation; therefore multiple measurements are available for analysis. Since changing atmospheric temperature has not an important role in geotechnical study of an earth-dam singly, the authors decided to investigate the environmental condition such as atmospheric temperature and reservoir water-level changes as input signal to the “dam-sensors-combination” system. Here the authors carried out their investigation using seven epochs of geodetic measurements between 2000 and 2008, moreover the measurements of four anchors inside an installed rod-extensometer between 2007 and 2013, settlement observations on settlement-plates in different levels between 2008 and 2013, and a long-time series of the daily observations of three installed soil-extensometers between 2005 and 2013. A significant correlation between temperature changes and soil-extensometer observations has been determined, besides the coherence method leads to common periods of 351 days between input and output time series. The weighting function method is applied to model the deformation of the dam using deformation measurements of installed soil-extensometer with temperature and water-level changes as effective sources. The RMS of difference between the estimated dam deformations from weighting function model compared to original measurements was calculated at 0.039 mm also from the point of correlation the original deformation measurements and modeled deformations are correlated at 95 %. The RMS of the difference between measurements and the predicted dam deformations using the weighting function model was calculated at 0.057 mm leading to a correlation value of 91 %. If the absolute values are transformed in percentage of the deformation, the maximum error of prediction is 10 %. The results show the success of weighting function method to model the deformation observations of the dam affected by input factors. One of the most important achievements of this paper is to draw a distinction between temperature as a systematic error sources and the other effective factors on the settlement observations of the earth-dam via comparison of the results of non-parametric methods on different sensors.

Research on the Calculation of the Security of High Concrete Arch Dam Based on the Finite Element Method

The study on the calculation of the security of high concrete arch dam based on the finite element method will be studied and analyzed in this paper. For high concrete arch dam deformation and stability under normal water level and maximum flood level will be calculated, and the stress of each section of the dam and batholith around will be checked and analyzed, then this paper will come to the dam security conclusion finally.

A New Method of Dam Safety Monitoring for Identifying Displacement Mutation

For the phenomenon of data pulsating indefinitely in observed data series, a safety monitoring model for concrete dam displacement is constructed in consideration of dynamic mutation’s blind spot based on dynamic cross-correlation factor index and cloud model theory. On the basis of evolvement analysis on dam deformation using uncertain dynamic system,while comprehensively applying numerical methods of phase space reconstruction, cloud model, wavelet analysis, a diagnosis method to predict abnormality variation of working state of dam is established. Project examples show the method can identify the dynamic mutation blind spot and be a better solution to eliminate its adverse influence on deformation series. Hereby, the new method can improve the reliability and scientific of dam displacement safety monitoring model.

Characteristics of the landslide dams induced by the 2008 Wenchuan earthquake and dynamic behavior analysis using large-scale shaking table tests

The Ms 8.0 Wenchuan earthquake triggered at least 257 landslide dams. More than 300 aftershocks with the magnitudes higher than Ms 4.0 occurred after the formation of these landslide dams, which might largely influence the structure and soil properties of these dams. This paper aims to comprehensively investigate the characteristics of the landslide dams induced by the 2008 Wenchuan earthquake, and study the dynamic behaviors of the landslide dams under aftershocks using large-scale shake table tests. First, the characteristics of the landslide dams, including the distribution, geometric parameters, stability and longevity, mitigation measures and the influence of the aftershocks are proposed. Then, two groups of shaking table tests to simulate the dynamic behaviors of two types of landslide dams under aftershocks are illustrated: one with quartz sand contained 10% kaolin (Dam I) and the other with quartz sands all (Dam II). Finally, the results of the tests, including the acceleration distribution, dam deformation and dam breaching process, are discussed. Through this study, it is found that the landslide dams caused by high-magnitude earthquakes have distinctive characteristics, which may largely influence the stability, breach process and risks of these dams. In the model tests, the accelerations are generally higher on the surface of the dams, either on the crest or on the both upstream and downstream slopes. The Dam I was prone to settlement and cracking. The aftershocks may not directly trigger the failures of landslide dams, but accelerate the overtopping failures by lowering the dam crest with settlement and cracking.

A phase space reconstruction based single channel ICA algorithm and its application in dam deformation analysis

Separating noise, systematic errors and deformation components that are caused by different forces such as water pressure and temperature should be identified from dam deformation monitoring data to facilitate effective dam deformation analysis and consequently determine the potential dam structural damage. As source signals are assumed to be mutually independent, independent component analysis (ICA) can be used to separate the source signals from their mixtures. In addition to signal independence, another requirement of ICA theory is that the number of mixtures should not be less than that of source signals. Unfortunately, in most cases of dam deformation monitoring, only a single channel of observed displacement data is available for each monitoring point. Therefore, ICA with single channel data input (called single channel ICA) is necessary in the application of deformation analysis. In this paper, we apply a phase space reconstruction based single channel ICA (PSR-ICA) algorithm to de-noise deformation monitoring data and separate deformation components introduced by different forces from these de-noised data. A numerical simulation is conducted, and results indicate that PSR-ICA is an efficient tool not only for denoising data but also for separating deformation components caused by different forces. PSR-ICA is then further utilised to process the displacement monitoring data of Wuqiangxi Dam. Results indicate that the two extracted main displacement components are nearly consistent with the displacement components; temperature and water level are used as variables and are computed by using a regression model. Both numerical simulated and real life dams demonstrate that PSR-ICA is an effective tool for separating deformation components by different causative forces and is therefore beneficial to dam deformation analysis.

Application of RBF Neural Network in Dam Deformation Prediction

Dam deformation is a multivariate complicated and nonlinear problem, it’s unable to establish accurate mathematical model.A dam deformation prediction model based on RBF neural network was constructed in this paper to enhance prediction accuracy. Three closely related factors in dam deformation are hydraulic components, temperature component and aging components ,they were selected as Input vector of RBF neural network, dam deformation measured value as a model target output. In Matlab 2011b simulation software,50 groups Fengman dam quantitative observation data from 2012 to 2013 as the sample data,45 groups were used in RBF neural network model training, other 5 groups were used in testing for the model. The simulation result shows that testing value is very close to the true value in this method, the average relative error close to 3%. Effectiveness of the dam deformation prediction based on RBF neural network is Verified by experiments.

Landslide dam deformation analysis under aftershocks using large-scale shaking table tests measured by videogrammetric technique

The Ms 8.0 Wenchuan earthquake triggered at least 257 landslide dams. More than 849 aftershocks with magnitudes higher than Ms 4.0 occurred after the Wenchuan earthquake by 12 March, 2012 (Shen et al., 2013), which might largely influence the structure and soil properties of these dams. This paper aims to study the dynamic deformation of landslide dams under aftershocks through larger scale shaking table tests. Videogrammetric technique was applied to measure the dynamic deformation of the model dams. Two groups of shaking table tests were conducted with two types of landslide dam materials: one with quartz sands containing 10% kaolin (Dam I) and the other with only quartz sands (Dam II). The dam deformation and its influencing factors were analyzed with the results measured by videogrammetric technique. The deformations were generally higher on the surface of the dams, either on the crest or on the both upstream and downstream slopes. Higher peak ground acceleration (PGA) resulted in larger dam deformations due to higher seismic force. The deformations under the combination of X- and Z-directional shakings were larger than those under X-directional shaking for sufficient vibratory compaction. Water rising led to the increase of dam deformations because that the water seepage reduced the effective soil stress, especially reduced the matric suction. The settlements of the dam composed of more fine particles were larger than that composed of large particle size because that the soil pores in the former were filled more sufficiently with fine particles. The aftershocks may not directly trigger the failures of landslide dams, but accelerate the overtopping failures by lowering the dam crest with settlement and cracking.

Structural health monitoring of an arch dam from static deformation

This paper presents an investigation of using long-term static deformation measurements for structural health monitoring (SHM) of Fei-Tsui dam, which is located in a very active seismic zone of Taiwan. A modeling technique is developed to characterize the measured static deformation, which is described as a function of the measured physical parameters, where the water level and temperature are the two most important variables affecting dam deformation. The developed modeling method integrates a linear least-squares technique and a nonlinear least-squares process to identify a model by minimizing the residual error between the identified model and the measured static deformation. The proposed modeling technique can also be used for the prediction of the long-term deformation based on the measured water level and temperature for SHM.

Spatio-temporal modelling of dam deformation using independent component analysis

Modelling dam deformation based on monitoring data plays an important role in the assessment of a dam’s safety. Traditional dam deformation modelling methods generally utilise single monitoring point. It means it is necessary to model for each monitoring point and the spatial correlation between points will not be considered using traditional modelling methods. Spatio-temporal modelling methods provide a way to model the dam deformation with only one functional expression and analyse the stability of dam in its entirety. Independent component analysis (ICA) is a statistical method of blind source separation (BSS) and can separate original signals from mixed observables. In this paper, ICA is introduced as a spatio-temporal modelling method for dam deformation. In this method, the deformation data series of all points were processed using ICA as input signals, and a few output independent signals were used to model. The real data experiment with displacement measurements by wire alignment of Wuqiangxi Dam was conducted and the results show that the output independent signals are correlated with physical responses of causative factors such as temperature and water level respectively. This discovery is beneficial in analysing the dam deformation. In addition, ICA is also an effective dimension reduced method for spatio-temporal modelling in dam deformation analysis applications.

Stress and Deformation Analysis of Concrete Face Rockfill Dam Based on ABAQUS

A new analysis method of stress and deformation of concrete face rockfill dam is established based on ABAQUS. This new approach includes secondary development of Duncan E-B material model and secondary development of Goodman frictional model of contact between concrete face and cushion. Meanwhile, contact characteristics is considered among concrete face and between concrete face and plinth. According to dam prototype observation, the analytic results are in good agreement with calculation results from the practical engineering, which indicates that the analysis method can be used widely.

Finite Element Analysis of Stress Deformation of Earth-Rock Dam on Narrow Valley

The three-dimentional finite element analysis is adopted to simulate and cauculate the stresses and deformations of a certain core rockfill dam on narrow velley, with Duncan-Chang E-ν model during its completion and operation periods by incremental loading.The results show that the stresses and deformations of core rockfill dam on narrow velley are allowble and the design proposal is reasonable, which provides the theoretical basis for similar engineering.

Sensitivity Analysis of Concrete Face Rock-Fill Dam Parametric Based on the Intelligent Algorithm

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 element simulation 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.

Earth-Rock Dam Deformation Monitoring Based on Three-Dimensional Laser Scanning Technology

Three-dimensional laser scanning can obtain the complete geometry information of the dam quickly and accurately, and then achieve the overall deformation monitoring, which breaks the traditional limitation of single point monitoring and local monitoring. In this paper, the complete point cloud data of the dam was obtained by three-dimensional laser scanning technology, and the surface model of the earth-rock dam was constructed by three-dimensional spherical projection surface dam construction algorithm. Then the accurate three-dimensional surface model of the earth-rock dam was acquired, and the first phase of the model as reference model,with different periods of point cloud data collected were analyzed with the reference model to obtain information about the dam deformation.

Experimental Study on Cracking, Reinforcement, and Overall Stability of the Xiaowan Super-High Arch Dam

The Xiaowan super-high arch dam has faced challenging construction problems. Here, we provide a scientifically-based reference for applying geomechanical model testing to support the nonlinear design of super-high arch dams. We applied experimental similarity theory and techniques. Based on four 3D geomechanical model tests, the dam stress characteristics, deformation distribution, and the safety factors of the dam foundation were identified and compared. We also analyzed cracking characteristics of the up- and downstream dam surfaces and induced joints in the dam heel, the rock mass failure process of the dam-foundation interface, and the abutments. We propose foundation reinforcement measures for weak rock masses, alteration zones, and other faults in the abutments based on the 3D and plane tests each at a different elevation. The results show that all dam deformations remained normal with no yielding or tensile cracking under a normal water load. The reinforced rock mass increased the crack initial safety in the dam heel and toe by ~20 %. The minimum crack initial safety factor (K 1) of the dam heel was 1.4. The induced joint in the dam heel contributed to a reduction in tensile stress at the upstream dam heel, improving K 1. Compared with similar projects following reinforcement measures, the abutment stiffness and overall stability of the Xiaowan arch dam satisfy operational requirements. Four years of monitoring operations show that key areas near the dam remained normal and the dam foundation is functioning well. Our results may also be applicable to the design and construction of similar projects worldwide.

Application of Independent Component Regression in Dam Deformation Analysis

There are relativity problem among the impact factors which effect dam deformation, morbid result would be caused when these factors are used to build the regression model, and the stability of model which is used to analysis and forecast the deformation of dam will be affected. Independent Components Analysis (ICA) combining with regression analysis can be used in dam deformation analysis owing ICA’s potential to remove relativity and provide statistical independence between factors. The simulation experiment and example showed that Independent Components Regression (ICR) can solve the relativity problem of the impact factors, and can give better explanation to the dependent variable. The ICR is a new way and has great potential applications in the field of deformation analysis.

Prediction Model of Concrete Dam Deformation Based on Adaptive Unscented Kalman Filter and BP Neural Network

By using unscented kalman filter (UKF) theory and introducing adaptive factor into BP neural network, a new prediction model of concrete dam deformation was proposed. Example shows that this model can improve the convergence speed of BP neural network, and the calculation precision of this model meets engineering requirements. Meanwhile, this model can be applied in the safety monitoring of other hydraulic engineering structure.

Effect of Embankment Soil Layers on Stress-Strain Characteristics

Dam embankments are complex geotechnical structures. In design of the earth dams, the finite element method (FEM) is very often used. The FEM is used in analysis of expected displacements, strains, and stresses of the structure caused by changeable loading or boundary conditions. Deformation of an embankment dam starts occurring during the construction of the dam. These deformations are caused by the increase of effective stresses during the construction of the consecutive layers of earth material and also by the effects of creep of material. In this study, Alavian earth dam was selected for stress-strain analysis using Geo-Studio software. The settlements from the single layer embankment simulations were compared with the settlements calculated for 3, 7, 10 and 15 soil layers considered in construction processes. Results showed that maximum displacement in single layer dam has happened in the crest of the dam. Increase in embankment layers, resulted in the maximum displacement creation in the middle of the downstream shell. The simulation layers for the construction have little effect on the stresses in the dam; however, that may cause a significant effect on the deformations of the dam.

Ant Colony Optimization Analysis on Overall Stability of High Arch Dam Basis of Field Monitoring

A dam ant colony optimization (D-ACO) analysis of the overall stability of high arch dams on complicated foundations is presented in this paper. A modified ant colony optimization (ACO) model is proposed for obtaining dam concrete and rock mechanical parameters. A typical dam parameter feedback problem is proposed for nonlinear back-analysis numerical model based on field monitoring deformation and ACO. The basic principle of the proposed model is the establishment of the objective function of optimizing real concrete and rock mechanical parameter. The feedback analysis is then implemented with a modified ant colony algorithm. The algorithm performance is satisfactory, and the accuracy is verified. The m groups of feedback parameters, used to run a nonlinear FEM code, and the displacement and stress distribution are discussed. A feedback analysis of the deformation of the Lijiaxia arch dam and based on the modified ant colony optimization method is also conducted. By considering various material parameters obtained using different analysis methods, comparative analyses were conducted on dam displacements, stress distribution characteristics, and overall dam stability. The comparison results show that the proposal model can effectively solve for feedback multiple parameters of dam concrete and rock material and basically satisfy assessment requirements for geotechnical structural engineering discipline.

Numerical simulation for deformation of landslide dam by overtopping water

Numerical simulation for deformation of landslide dam by overtopping water

Numerical Simulation of Landslide Dam Deformation by Overtopping Flow

Numerical Simulation of Landslide Dam Deformation by Overtopping Flow