Dam Deformation Research Articles

Smart Monitoring of a Super High Arch Dam during the First Reservoir-Filling Phase

The structural behavior during the first reservoir-filling phase is significant for evaluating a super high arch dam’s safety. This paper presents an in situ monitoring network of the Xiluodu Dam in Yunnan, China, including a deformation monitoring system using geodetic and nongeodetic monitoring. The system also includes a refined thermal monitoring system based on a slab-level active cooling system. The thermal–structural decoupling numerical analysis method for a dam–water–foundation system is presented in this study with considerations of viscoelasticity material properties and internal/external thermal loads. The structural behavior of the Xiluodu Dam during the first reservoir-filling phase is analyzed using the smart monitoring system with combination of the in situ monitoring technique and the numerical simulation method. The in situ monitoring result can provide intuitional instructions of the structural behavior, showing a positive correlation between the dam deformation and the reservoir water level. The monitoring results are also used as the verification reference of the numerical model. The distribution characteristics of the displacement and stress of the dam subjected to load cases such as nonimpounding, impounding process, and the normal operating water level are discussed and predicted.

Analysis of Slurry Diffusion Mechanism of the Splitting Grouted in Dam Reinforcement

The reinforcement of disease dam in China is one urgent problem to be solved. Because the rivers and lakes in south of China are quite a lot, and many dams have been built in these rivers and lakes for power station and farmland irrigation in the 1960s or 1970s. Those dams are being “ill” because the building technology at that time is under-developed which causes those dams mostly to be being “ill”. With the increase of dam operation time, the majority of disease dams have been becoming seriously and have to be reinforced to extend the operation time. As one techology of dam reinforcement methods for environmental protection and save material, the splitting grouted has been created firstly and used in many dam reinforcements in China. With this technology, a certain amount of grouting pressure is applied at the dam axis to control the split dam body at first; after that, an appropriate amount of seriflux is injected into the dam body to fill the holes and crannies in the dam body, and form an effective anti-seepage solid bodies, thus improving the stress state of dam body and achieving the consolidating the dam structure. In the reinforcement technology, the slurry has been filled inside dam body, the slurry diffusion mechanism is the important for studying the working principle of splitting grouted. So, based on the numerical simulation, the slurry diffusion law has been simulated to investigate the mechanism of slurry diffusion. At the same time, the deformation of dam during the splitting grouted has been comparative demonstration. Through those numerical calculation, it can be founded that the strength of dam is improved and cracks are filled which because the splitting slurry has been diffusing from grouting port to dam body, and the dam has been moving to both sides of dam body. Those would lead to fill the fractures in dam body and form the impervious wall along the grouted ports.

Experimental study of the influence of sand grain size and inflow discharge on landslide dam deformation process and outflow discharge

Experimental study of the influence of sand grain size and inflow discharge on landslide dam deformation process and outflow discharge

Structural Safety Monitoring of High Arch Dam Using Improved ABC-BP Model

The establishment of a structural safety monitoring model of a dam is necessary for the evaluation of the dam’s deformation status. The structural safety monitoring method based on the monitoring data is widely used in traditional research. On the basis of the analysis of the high arch dam’s deformation principles, this study proposes a structural safety monitoring method derived from the dam deformation monitoring data. The method first analyzes and establishes the spatial and temporal distribution of high arch dam’s safety monitoring, overcoming the standard artificial bee colony (ABC) algorithm’s shortcoming of easily falling into the local optimum by adopting the adaptive proportion and average Euclidean distance afterwards. The improved ABC algorithm is used to optimize the backpropagation (BP) neural network’s initial weight and threshold. The application example proves that ABC-BP model’s improvement method is important for the establishment of a high arch deformation safety monitoring model and can effectively improve the model’s fitting and forecasting ability. This method provides a reference for the establishment of a structural safety monitoring model of dam and provides guidance for the establishment of a forecasting model in other fields.

Potential of C-Band SAR Interferometry for Dam Monitoring

Despite the recent popularity achieved by the modern X-band SAR sensors, mainly due to their high spatial resolutions which enable the detection of deformation components impossible so far, such as thermal expansion, SAR C-band sensors continue to be of great utility and with a great future in the deformation monitoring field, namely for critical structure monitoring, such as dams. The new ESA missions (Sentinel-1A and 1B) and the extension of the Canadian Radarsat mission corroborate this finding.In this paper the possibility of using spaceborne SAR sensors for dam monitoring is addressed in terms of feasibility and applications. The presented results show the potential of C-band sensors for the particular case of dam monitoring and can be handful to recognize the applicability of new Sentinel-1 data (since 2014) for continuous monitoring of dam deformations.

Prediction of Permanent Earthquake-Induced Deformation in Earth Dams and Embankments Using Artificial Neural Networks

This research intends to develop a method based on the Artificial Neural Network (ANN) to predict permanent earthquake-induced deformation of the earth dams and embankments. For this purpose, data sets of observations from 152 published case histories on the performance of the earth dams and embankments, during the past earthquakes, was used. In order to predict earthquake-induced deformation of the earth dams and embankments a Multi-Layer Perceptron (MLP) analysis was used. A four-layer, feed-forward, back- propagation neural network, with a topology of 7-9-7-1 was found to be optimum. The results showed that an appropriately trained neural network could reliably predict permanent earthquake-induced deformation of the earth dams and embankments.

Deformation Characteristics and Control Techniques at the Shiziping Earth Core Rockfill Dam

AbstractThis paper presents a representative engineering case, the Shiziping dam, to illustrate deformation controls of highrise earth core rockfill dams in seismic areas. Techniques for controlling dam deformation, including structure design, foundation treatment, material properties, and construction are discussed in detail. Field monitoring data and deformation characteristics were reviewed to verify control effectiveness. The deformation during the construction and initial impoundment period accounted for 70–85% of the overall deformation; the deformation was primarily influenced by weight, wetting behavior, and creep. Creep stabilized 7 or 8 months after the completion of construction. The total deformation is caused by fill and foundation materials. Uneven deformation is mainly caused by foundation shape, foundation compression symmetry, and uniformity of fill materials. Uneven deformation may be improved by using reasonable dam zone and fill material designs and appropriately increasing core wall c...

Fuzzy evaluation on seismic behavior of reservoir dams during the 2008 Wenchuan earthquake, China

The post-earthquake rapid risk evaluation on the reservoir dams plays an important role in the emergency danger disposal and reinforcement. The fuzzy Data Envelopment Analysis/Assurance Region (DEA/AR) approach was introduced evaluating the seismic behavior of reservoir dams, in which the seismic risk of dam site, the structure characteristics of reservoir dam, and pre-earthquake state of dams were taken as input variables; in the meantime the seismic crack, leakage and deformation of dams induced by the earthquake were taken as output variables. The proposed DEA/AR approach was adopted to evaluate the seismic behavior of 19 reservoir dams suffered from Wenchuan earthquake in Luojiang County, Sichuan Province. The input and output variable values all originated from the post-earthquake field investigation data. And the weight values of DEA/AR model were determined by the entropy weight method which was able to avoid the interference from subjective consciousness. The evaluation results on the seismic behavior obtained from DEA/AR approach were mainly consistent with those from the experts in the field, which verified that the approach was valid and rational. The proposed DEA/AR approach was based on the objective data and the cognitive ability of the model self to give the evaluation results, which was adaptive for the situation that the seismic behaviors of the reservoir dams were not easy to distinguish. A ranking method was recommended to judge the order of quality of seismic behavior of the evaluated reservoir dams. The ranking results could serve for the post-earthquake emergency disposal and reinforcement.

APPLICATION OF AN ELASTOPLASTIC MODEL TO PREDICT BEHAVIORS OF CONCRETE-FACED ROCK-FILL DAM UNDER COMPLEX LOADING CONDITIONS

In this research, a simplified rotational kinematic hardening model with the concept of sub-loading was used to predict behaviors of Concrete-Faced Rock-fill Dam under complex loading conditions. The model can overcome the shortcomings of classic elastoplastic model (i.e. soil behaviors under cyclic loading-unloading can be predicted). Elastoplastic formula of the model was presented in detail. Then this model was verified with test results of coarse grained soils, under both monotonic loading and cyclic loading-unloading conditions. This model was also applied to analyze deformation of Shuibuya rock-fill dam, computed results and in-situ measurements are compared. Results showed that computed results were consistent with in-situ measurements in both construction and operation period. Results also showed that permanent deformation that was caused by fluctuations of the reservoir level can also be predicted by this rotational kinematic hardening model.

Evaluating the safety of high arch dams with fractures based on numerical simulation and geomechanical model testing

It is important to estimate the probability of fracture extension and its impact on the safety of arch dams with fractures. Numerical simulation and geomechanical model test were combined to evaluate the overall stability and the extension probability of fractures. Numerical simulation forecasted the dam displacement and the operating behavior based on the parameters obtained from the back analysis. Geomechanical model test was based on small block masonry and the models with or without fractures were both tested. The results show that the deformation of dams is in line with general rules at a normal water load and the extension probability of the existing fractures is very small, which has no significant impact on the global stability of dams. Moreover, the failure process of arch dams with the existing fractures in dams at overload scenarios is similar to the one without the embedded fractures, i.e., the failure crack which is not caused by the existing fractures inside comes into being on the surface of dams itself.

Displacement response of a concrete arch dam to seasonal temperature fluctuations and reservoir level rise during the first filling period: evidence from geodetic data

The present study evaluates the dynamic behaviour of the Ermenek Dam, the second highest dam in Turkey, based on conventional geodetic measurements and Finite Element Model (FEM) analyses during its first filling period. In total, eight periods of measured deformation are considered from the end of construction until the reservoir reached its full capacity. The displacement response of the dam to the reservoir level and to seasonal temperature variations is examined in detail. Time series of apparent total displacements at the middle of the crest of the dam exhibits periodicity and linear trends. Correlation analysis revealed that periodic and linear displacement responses of the dam are related to variations of seasonal temperature and linearly increased reservoir level, respectively, indicating a relation between temperature, water load and dam deformation. It is also concluded that measured deformations based on geodetic data show good agreement with the predicted deformation obtained by the FEM analysis.

The Analysis of Stress, Deformation and Arch Effect of the Lianghekou Earth-rockfill Dam

Deformation, stress and arch effect are problems of interest for high earth- rockfill dams. Deformations and stresses during construction, impoundment and operation stages of Lianghekou earth-rockfill dam were studied through numerical methods. The filling materials were modeled by using the Mohr- Coulomb and Burgers models. As a result, the maximum vertical displacement is located in the middle of the dam height during every stage. The vertical displacement increases evidently during operation stage due to the time dependent behavior of the dam materials. The dam moves in the downstream direction after impoundment. The horizontal displacements of upstream rockfill and downstream rockfill increase during operation stage. The level of arch effect increases evidently after 10 years of operation due to the time dependent behavior of dam materials. The possibility of horizontal cracks and hydraulic fracturing is little during construction stage and impoundment stage, but increases evidently after operation.

The GA-BP prediction model considering chaos effect of dam displacement residual

Aiming at the problems of residual chaos effect in dam common monitoring model and the fitting degree of model regression methods, the dam deformation observation data fitting residual was extracted with genetic neural network (GA-BP) algorithm by combining the advantage of genetic algorithm and neural network. For the chaotic characteristics of deformation fitting residual, chaos theory was used to analyze residual series, and the residual prediction results were added in GA-BP prediction model. Hereby, the GA-BP prediction model considering chaos effect of dam displacement residual was established. Example showed that the calculation accuracy and convergence rate of this prediction model were all improved, and the prediction effect of this model was better. Furthermore, the modeling methods introduced in this paper could be applied to security early warning in slope and other hydraulic structures.

The feedback of rheological deformation of concrete face rockfill dam based on engineering analogy method

In view of relationship for axial strain, volumetric strain and the generalized shear strain are different in different documents when the rheology deformation of rockfill dam is analyzed. Volume rheology and shear rheology are assumed different, three-dimensional rheology rate of rockfill material is deduced and the reasonable relationship for axial strain, volumetric strain and the generalized shear strain is also deduced. Since the difference between indoor test parameters and rockfill dams actual parameters is bigger, the measured deformation for the rockfill dam to be built cant timely obtain and the rockfill dams actual parameters also cant timely feedack. The engineering analogical method is presented for the feedback of rockfill dams actual parameters. The measued deformation for already built rockfill dam, with similar dam height, upstream and downstream slope rate, valley shape factor and rock behaviour of rockfill material, is selected, and the parameters for rockfill dam to be built is feedback with the rheological numerical calculation. Example analysis shows that, analogy the measured deformation for the already built rockfill dam, the specific value between actual modulus factor of rockfill dam to be built and indoor test modulus factor is about 0.7; the specific value between the largest settlement and the dam height is 0.667%-0.720% when considering rheological deformation; the specific value between concrete faces deflection and the largest settlement is 0.252-0.272, and the incremental settlement of dam crest increses when the rheological parameter c decreases, but the value is small, the incremental settlement of dam crest is 3.537 cm after running 3 years.

Study on Optimal Grouting Timing for Controlling Uplift Deformation of a Super High Arch Dam

A grouting model is developed for use during the grouting of the complex foundation of a super high arch dam. The purpose as to determine the optimal grouting timing and appropriate grouting pressure involved in controlling the uplift deformation of the dam. The model determines the optimal grouting time as the height of the arch dam increases with the concrete pouring, by checking the tensile stresses in the dam against standard specifications. The appropriate grouting pressures are given on the basis of the actual grouting pressures monitored during the upstream riverbed foundation grouting. An engineering procedure, applying the model, was then proposed and used during foundation grouting under the toe block of the Xiluodu super high-arch dam in south-western China. The quality of the foundation grouting was evaluated against the results from pressurized water permeability tests, acoustic wave velocity tests, elastic modulus tests and panoramic photographing of the rockmass on completion of the foundation grouting. The results indicated that the proposed grouting model can be applied to effectively reduce the uplift deformation and associated cracking risk for super high arch dams, and it can be concluded that the proposed engineering grouting procedure is a valuable tool for improving foundation grouting under the toe blocks of a super high arch dam.

Investigation on the Data Processing in Automation Monitoring System Designed for Dam Deformation

Deformation monitoring for dam is quite important and it can be directly used to reflect the running status to keep the operation safely. In order to meet the demand for monitoring the dam, global position system (GPS) is used to develop a monitoring system with high efficiency. In this paper, we developed a monitoring system for deformation monitoring for the dam with wireless data transmission. In order to reduce the energy consumption, the regulation of its working condition has been redesigned according to the monitoring object's own characteristics. At the same time, the data compression is also used in the GPS data processing to reduce the energy consumption. The compression method is divided into two steps. In the preprocessing, data amount can be removed about half of the amount, and Hoffman coding compression rate and the style conversion compression ratio are relatively small. The total compression rate is more than 60%. Compared with the existing compression algorithms, the new developed method has higher compression rate. When the data collection rate is higher, the compression will be higher, and the reason may be that the time information and position information are compressed when the data collection rate is higher. This method can be used to process the data effectively and improve the data transmitting efficiency.

Application of the Periodic Average System Model in Dam Deformation Analysis

Dams are among the most important hydraulic engineering facilities used for water supply, flood control, and hydroelectric power. Monitoring of dams is crucial since deformation might have occurred. How to obtain the deformation information and then judge the safe conditions is the key and difficult problem in dam deformation monitoring field. This paper proposes the periodic average system model and creates the concept of “settlement activity” based on the dam deformation issue. Long-term deformation monitoring data is carried out in a pumped-storage power station, this model combined with settlement activity is used to make the single point deformation analysis, and then the whole settlement activity profile is drawn by clustering analysis. Considering the cumulative settlement value of every point, the dam deformation trend is analyzed in an intuitive effect way. The analysis mode of combined single point with multipoints is realized. The results show that the key deformation information of the dam can be easily grasped by the application of the periodic average system model combined with the distribution diagram of settlement activity. And, above all, the ideas of this research provide an effective method for dam deformation analysis.

Seismic Fortification Analysis of the Guoduo Gravity Dam in Tibet, China

The primary aim of this research was to analyze the seismic performance of the Guoduo gravity dam. A nonlinear FEM method was implemented to study the deformation, stress, and overall stability of dam under both static and dynamic loading conditions, including both normal and overloading conditions. A dam seismic failure risk control method is proposed based on the cracking mechanism induced by the dynamic load to ensure dam safety and stability. Numerical simulation revealed that (1) under normal static and dynamic loading the symmetry of the displacement distributions is good, showing that the dam abutments and riverbed foundation have good overall stiffness. The stress distribution is a safe one for operation under both normal water loading and seismic loading. (2) Attention should be paid to the reinforcement design of outlets of the diversion dam monoliths, and enhance the capability of sustaining that tensile stress of dam monoliths. (3) The shape of the dam profile has a significant effect on the dynamic response of the dam. (4) By employing the “overload safety factor method,” the overall seismic fortification is as follows:K1=1.5,K2=2~3, andK3=3~4.

Continuous displacement monitoring of rockfill dam during earthquakes by using global positioning system

Exterior deformation is one of the most important items to measure when managing the safety of embankment dams. A conventional surveying method, using targets installed on the crest and the slopes of the embankment dams, is usually employed to measure exterior deformation. It is difficult, however, to measure the deformation by such a method immediately after an earthquake or other emergency. A displacement monitoring system using GPS (Global Positioning System) was developed to continuously monitor the deformation of dams. The system can provide three-dimensional displacements at many points simultaneously with high accuracy at the millimeter level. Ishibuchi Dam is a concrete-face rock-fill dam; it is one of the oldest rock-fill dams in Japan. After the large settlement caused by the Iwate-Miyagi Nairiku Earthquake of 2008, the above GPS displacement monitoring system was installed to continuously monitor the deformation behavior. On March 11, 2011, the Great East Japan Earthquake struck near the northeast coast of Honshu Island. This paper describes the results of the deformation monitoring of Ishibuchi Dam before, during, and after the Great East Japan Earthquake, and discusses the validity of the system for the safe management of dams after earthquakes. Language: ja

Back-analysis of soil parameters of the Malutang II concrete face rockfill dam using parallel mutation particle swarm optimization

Deformation control is a central problem in earth-rockfill dam design. The finite element method (FEM) is the primary method used to analyze and predict the deformation of earth-rockfill dams. The parameters of the constitutive model of soil used in earth-rockfill dams determine the FEM analysis results. Using prototype monitoring displacements, the soil parameters of the Malutang II concrete face rockfill dam were back-analyzed using parallel mutation particle swarm optimization. The calculated displacements of the back-analyzed soil parameters are consistent with the prototype monitoring results. The parallel mutation particle swarm optimization has a high optimization rate and can be used in large-scale practical engineering applications. The back-analysis results indicate that the deformation moduli of rockfills in the Malutang II are affected by construction situ.