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The overtopping process, resulting from landslide-induced waves, has the potential to cause significant damage to downstream infrastructures. To minimize the associated losses, it is essential to study the overtopping phenomenon. Limited research has been conducted on physical modeling and volumetric calculation of wave overtopping in reservoirs with arch dams. The study designed a physical model experiment at a geometric scale of 1∶70 to investigate the occurrence of wave overtopping caused by landslides in arch dam reservoir areas at the maximum water depth scenario. Equations developed for straight dams, such as gravity dams, overestimate the volume of overtopping caused by landslides in arch dam reservoirs due to structural dissimilarities. Two volumetric overtopping equations specifically applicable to arch dams were derived through regression analysis. Additionally, the analysis of model experimental data unveiled the distribution pattern of the initial wave amplitude along the dam face, the overtopping duration characteristics, as well as the factors influencing the volume of overtopping. The underlying causes of these phenomena are explained in this paper. This study offers valuable insights into comprehending the intricate process of wave overtopping generated by landslides. These insights encompass the estimation of overtopping volume, as well as the safety assessment of downstream. [ABSTRACT FROM AUTHOR]

It is essential to understand how failure mechanisms work in arch dams and, in particular, their most common manifestation: cracking. In this paper, the different types of cracking are explained in terms of their causes and consequences. Then, an exhaustive literature review is carried out that results in a detailed compilation of the characteristics of 38 cracked arch dams from all over the world, including crack characteristics (zone, position, dimensions and probable cause). This review is restricted to only those dams for which information on the position of the cracks or dam displacements is publicly available. As part of the review, a brief summary of key data for each dam is included, as well as a compilation of published crack diagrams. The positions of the cracks of all the dams are classified using diagrams in relation to the type of dam and the origin of the crack. Finally, the distribution of some dam parameters and crack features is analyzed by studying the relationships between them. [ABSTRACT FROM AUTHOR]

Since ancient times, dams have been built to store water, control rivers, and irrigate agricultural land to meet human needs. By the end of the 19th century, hydroelectric power stations arose and extended the purposes of dams. Today, dams can be seen as part of the renewable energy supply infrastructure. The word dam comes from French and is defined in dictionaries using words like strange, dike, and obstacle. In other words, a dam is a structure that stores water and directs it to the desired location, with a dam being built in front of river valleys. Dams built on rivers serve various purposes such as the supply of drinking water, agricultural irrigation, flood control, the supply of industrial water, power generation, recreation, the movement control of solids, and fisheries. Dams can also be built in a catchment area to capture and store the rainwater in arid and semi-arid areas. Dams can be built from concrete or natural materials such as earth and rock. There are various types of dams: embankment dams (earth-fill dams, rock-fill dams, and rock-fill dams with concrete faces) and rigid dams (gravity dams, rolled compacted concrete dams, arch dams, and buttress dams). A gravity dam is a straight wall of stone masonry or earthen material that can withstand the full force of the water pressure. In other words, the pressure of the water transfers the vertical compressive forces and horizontal shear forces to the foundations beneath the dam. The strength of a gravity dam ultimately depends on its weight and the strength of its foundations. Most dams built in ancient times were constructed as gravity dams. An arch dam, on the other hand, has a convex curved surface that faces the water. The forces generated by the water pressure are transferred to the sides of the structure by horizontal lines. The horizontal, normal, and shear forces resist the weight at the edges. When viewed in a horizontal section, an arch dam has a curved shape. This type of dam can also resist water pressure due to its particular shape that allows the transfer of the forces generated by the stored water to the rock foundations. This article takes a detailed look at hydraulic engineering in dams over the millennia. Lessons should be learned from the successful and unsuccessful applications and operations of dams. Water resource managers, policymakers, and stakeholders can use these lessons to achieve sustainable development goals in times of climate change and water crisis. [ABSTRACT FROM AUTHOR]

The strengthening of arch dam foundation is an important engineering measure to ensure the stability of dam abutment and the safety of arch dams. This paper took the reinforcement measures for the foundation of Dongzhuang arch dam as the research object, systematically simulated the discontinuity layer, mud fissures, wide joints and corresponding reinforcement measures of the dam abutment rock mass. The finite element analysis was conducted on the reinforcement effect of the dam foundation using elastic-plastic constitutive law. The calculation results indicate that the foundation reinforcement measures have little effect on the maximum displacement and stress of the dam body, but to some extent, they reduce the yield zone of the dam body and the foundation surface, improving the stress on the dam body. Through overload calculation and analysis, it is found that the foundation reinforcement measures have little effect on the plastic zone of the arch dam body, but the yield zone of the foundation surface is significantly reduced after the foundation reinforcement. The foundation reinforcement measures have a relatively smaller impact on the yield zone volume of fault f5 and muddy fissure Rnj3, but a significant impact on the yield zone volume of large fissure L22. In summary, the foundation reinforcement measures taken for Dongzhuang arch dam have improved the stress on the dam body and foundation, and improved the stability of the dam foundation. [ABSTRACT FROM AUTHOR]

Running a numerical model for a cracked arch dam that takes into account all the particularities of the materials and dam with a high level of detail has a great computational cost involved. For this reason, it is usual to simplify such a model in search of a simpler solution while preserving the characteristic of being representative, with all the particularities that the model of an arch dam has. A common simplification lies in not considering open transverse joints in the construction phase of a cracked dam. An aim of this study is to propose a methodology that combines open joints and cracking, something on which, to the authors' knowledge, no studies have been published. An additional goal is a study of the need and adequacy of different approaches on performance (computational time) and its consequences for model accuracy. For this purpose, an accurate methodology for a stationary finite element method numerical simulation of deformations in cracked arch dams is presented. Using a tetrahedron mesh of a real dam, different simplifications commonly used in numerical models are compared. It is concluded that some of the standard simplifications produce a significant effect on the computation time and accuracy of the results. [ABSTRACT FROM AUTHOR]

It is essential to understand how failure mechanisms work in arch dams and, in particular, their most common manifestation: cracking. In this paper, the different types of cracking are explained in terms of their causes and consequences. Then, an exhaustive literature review is carried out that results in a detailed compilation of the characteristics of 38 cracked arch dams from all over the world, including crack characteristics (zone, position, dimensions and probable cause). This review is restricted to only those dams for which information on the position of the cracks or dam displacements is publicly available. As part of the review, a brief summary of key data for each dam is included, as well as a compilation of published crack diagrams. The positions of the cracks of all the dams are classified using diagrams in relation to the type of dam and the origin of the crack. Finally, the distribution of some dam parameters and crack features is analyzed by studying the relationships between them.

Since ancient times, dams have been built to store water, control rivers, and irrigate agricultural land to meet human needs. By the end of the 19th century, hydroelectric power stations arose and extended the purposes of dams. Today, dams can be seen as part of the renewable energy supply infrastructure. The word dam comes from French and is defined in dictionaries using words like strange, dike, and obstacle. In other words, a dam is a structure that stores water and directs it to the desired location, with a dam being built in front of river valleys. Dams built on rivers serve various purposes such as the supply of drinking water, agricultural irrigation, flood control, the supply of industrial water, power generation, recreation, the movement control of solids, and fisheries. Dams can also be built in a catchment area to capture and store the rainwater in arid and semi-arid areas. Dams can be built from concrete or natural materials such as earth and rock. There are various types of dams: embankment dams (earth-fill dams, rock-fill dams, and rock-fill dams with concrete faces) and rigid dams (gravity dams, rolled compacted concrete dams, arch dams, and buttress dams). A gravity dam is a straight wall of stone masonry or earthen material that can withstand the full force of the water pressure. In other words, the pressure of the water transfers the vertical compressive forces and horizontal shear forces to the foundations beneath the dam. The strength of a gravity dam ultimately depends on its weight and the strength of its foundations. Most dams built in ancient times were constructed as gravity dams. An arch dam, on the other hand, has a convex curved surface that faces the water. The forces generated by the water pressure are transferred to the sides of the structure by horizontal lines. The horizontal, normal, and shear forces resist the weight at the edges. When viewed in a horizontal section, an arch dam has a curved shape. This type of dam can also resist water pressure due to its particular shape that allows the transfer of the forces generated by the stored water to the rock foundations. This article takes a detailed look at hydraulic engineering in dams over the millennia. Lessons should be learned from the successful and unsuccessful applications and operations of dams. Water resource managers, policymakers, and stakeholders can use these lessons to achieve sustainable development goals in times of climate change and water crisis.

Uncertainty in modal characteristics due to output-only system identification methods has been a challenge in operational modal analysis. The present study aims to extract modal parameters of Karun IV Dam (the highest arch dam in Iran) using the balanced stochastic subspace identification (B-SSI) and investigate the influence of user-defined parameters (i.e., columns and block rows of Hankel Matrix) on the uncertainty of the results. The effects of noise caused by numerical instabilities were first filtered using the inverse process by the condition number. Subsequently, the modal properties were homogenized with spatial clustering of applications with noise (DBSCAN) to remove the outlier and spurious characteristics. Then, the physical modes were validated by inspecting the complexity of the mode shapes based on the mode complexity factor criterion. Finally, the coefficient of variation (CV) of the validated clusters was employed to conduct a sensitivity analysis performed concerning the dimensions of the Hankel matrix to find the optimal models (with the minimum error in estimating the modal characteristics). The results indicated that the proposed method prevented the emergence of computational and noisy modes by regulating the extracted models, such that the first model of the structure was extracted with an error of less than 10% compared to the numerical model. [ABSTRACT FROM AUTHOR]

The stability of the arch dam shoulder is an important element in the analysis of the safety and stability of arch dams. The classical calculation method of arch dam shoulder slip resistance needs to assume the bottom sliding surface of the dam shoulder slider and ignore the influence of the fault and fracture joint group in the rock body of the dam shoulder on its shoulder slip resistance stability. In order to take into account the influence of faults and fracture joint groups to the rock mass, this paper used genetic algorithm to search for the critical sliding surface of the dam shoulder anti-slip based on the time course analysis method and analyzed the change of vibration intensity anywhere on the critical sliding surface of the dam shoulder slider. The slip resistance of the concrete arch dam shoulder was investigated in terms of sensitivity to shear strength parameters and ground vibration. The study result shows that the friction coefficient of the structural surface has less influence to the slip resistance stability of the dam shoulder, while the slip resistance stability performance of the dam shoulder is most sensitive to the cohesive force on the rock bridge, and the influence of cohesive force to the slip resistance stability performance is stronger than that of the friction coefficient, and the influence of ground vibration to the slip resistance stability performance of the arch dam shoulder is weaker. [ABSTRACT FROM AUTHOR]

In the concrete pouring of the high arch dam, multiple cable cranes usually pour multiple pouring blocks based on strips. So the key to improving construction efficiency is to optimize cable cranes to the coordination of pouring blocks strips. The difference of transportation distance and strip area leads to different pouring efficiency of each cable crane, and simple equal surface of the pouring block hardly guarantees the strip collaborative pouring rise, then the pouring efficiency of the cable crane group is affected. In order to solve the above problems, this paper establishes an intelligent configuration model of cable crane group, which takes into account the pouring cycle time and load balance. Firstly, the pouring strip is divided for the area where the coverage of each cable crane overlaps with the pouring block and the configuration of cable crane group and pouring blocks is transformed into a combination optimization problem of the cable crane group and the strips. Subsequently, a "micro-matching" model which bridges the cable machine and multiple strips is proposed. The many-to-many relationship between cable cranes and pouring blocks is transformed into a one-to-one matching relationship between the cable crane and the micro strip, and the "micro-matching" integral expression of the pouring configuration optimization is established. Finally, the optimal configuration scheme of the cable crane group is obtained with the optimization objectives of cycle time and load balancing, and the coordinated rise of pouring strips is realized. The pouring configuration example of Baihetan arch dam shows that the pouring cycle time and lifting load of the cable crane is basically balanced. The average deviation of the upper cable crane pouring strength is -6.8%, and the average deviation of the lower cable crane pouring strength is 5.1%. This method has good adaptability to the change of the number of cable crane and pouring block, and has certain intelligent configuration ability. [ABSTRACT FROM AUTHOR]

The structural behavior of the Xiaowan ultrahigh arch dam is primarily influenced by external loads and time-varying characteristics of dam concrete and foundation rock mass during long-term operation. According to overload testing with a geological model and the measured time series of installed perpendicular lines, the space and time evolution characteristics of the arch dam structure were analyzed, and its mechanical performance was evaluated. Subsequently, the deformation centroid of the deflective curve was suggested to indicate the magnitude and unique distribution rules for a typical dam section using the measured deformation values at multi-monitoring points. The ellipse equations of the critical ellipsoid for the centroid were derived from the historical measured time series. Hydrostatic and seasonal components were extracted from the measured deformation values with a traditional statistical model, and residuals were adopted as a grey component. A time-varying grey model was developed to accurately predict the evolution of the deformation behavior of the ultrahigh arch dam during future operation. In the developed model, constant coefficients were modified so as to be time-dependent functions, and the prediction accuracy was significantly improved through introduction of a forgetting factor. Finally, the critical threshold was estimated, and predicted ellipsoids were derived for the Xiaowan arch dam. The findings of this study can provide technical support for safety evaluation of the actual operation of ultrahigh arch dams and help to provide early warning of abnormal changes.

Running a numerical model for a cracked arch dam that takes into account all the particularities of the materials and dam with a high level of detail has a great computational cost involved. For this reason, it is usual to simplify such a model in search of a simpler solution while preserving the characteristic of being representative, with all the particularities that the model of an arch dam has. A common simplification lies in not considering open transverse joints in the construction phase of a cracked dam. An aim of this study is to propose a methodology that combines open joints and cracking, something on which, to the authors’ knowledge, no studies have been published. An additional goal is a study of the need and adequacy of different approaches on performance (computational time) and its consequences for model accuracy. For this purpose, an accurate methodology for a stationary finite element method numerical simulation of deformations in cracked arch dams is presented. Using a tetrahedron mesh of a real dam, different simplifications commonly used in numerical models are compared. It is concluded that some of the standard simplifications produce a significant effect on the computation time and accuracy of the results.

The issue of dam type selection is a prevalent challenge in water resource allocation engineering. The site of the Y2 dam in China is suitable for building concrete arch dams and roller-compacted concrete (RCC) gravity dams. To determine which dam type is better in terms of construction progress, this paper proposes a multiattribute decision-making method based on construction simulation. First, the construction characteristics of concrete dams are analyzed, and the construction simulation systems for arch dams and gravity dams are developed based on construction simulation theory. Then, for each dam type, the initial construction schemes are used as the input of the simulation systems, and attribute values of construction progress are output. Secondly, a multiattribute decision-making method is used to select the typical scheme of each dam type from these initial schemes. Finally, the simulation results of the typical schemes for the arch dam and the RCC gravity dam are compared, to determine the optimal dam type for the Y2 dam. The results show that for the Y2 dam, the construction period of the arch dam is 34 months, and that of the RCC gravity dam is 28 months. From the perspective of construction progress, the Y2 dam type should select the RCC gravity dam. Compared with similar dams that have been built, it is concluded that the simulated progress result conforms to the current actual construction level, which also verifies the correctness of the calculation results and the reliability of the construction simulation. [ABSTRACT FROM AUTHOR]

Traditional dam deformation prediction methods are mostly based on statistical models, which cannot well consider the nonlinear relationship between input variables and output variables, and the model adjustment process is complicated, time-consuming, and prone to over-fitting. This study proposed a Gaussian process regression analysis method for dam deformation prediction combined with nonlinear kernel functions. Taking the measured monitoring data of a high concrete arch dam as an example, it was used for the model establishment and evaluation verification. Three common deformation prediction methods were used as comparative analysis methods. The test results show that the method is significantly better than the comparison method when considering multiple quantitative regression accuracy evaluation indicators, which verifies the effectiveness and generalization ability of the proposed model. This method can give probabilistic dam deformation interval values, which is of great significance for dam abnormal monitoring data evaluation and abnormal behavior diagnosis. [ABSTRACT FROM AUTHOR]

The deformation characteristic of the arch dam can directly reflect its service performance, which can be analyzed on the basis of the dam deformation field. However, restricted by the limited number of dam monitoring points and the inhomogeneity of materials, an accurate measurement of arch dam deformation field is difficult to estimate by using the existing common methods, such as the spatial interpolation methods and the finite element method (FEM). With the aim of ensuring arch dam structure safety, the ordinary kriging interpolation method, combined with FEM, is proposed for arch dam deformation field estimation, in this study. Given the inversion of the computation parameters of the arch dam, FEM is used to calculate the basic arch dam deformation. Subsequently, the ordinary kriging interpolation method is introduced to estimate the spatial variance deformation at each point of the arch dam. One superhigh arch dam in China is selected as a case study; two additional methods are introduced as comparisons that are based on a numerical experiment and the actual monitoring data. The experimental results show that the proposed method considerably improves the accuracy and computational efficiency of the arch dam deformation field estimation and that it is of great practical importance for characterizing the deformation behavior of arch dams. [ABSTRACT FROM AUTHOR]

Copyright of Water Conservancy Science & Techonlogy & Economy is the property of Water Conservancy Science & Technology & Economy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During the concrete pouring of arch dams in the high-temperature season, solar radiation significantly influences the surface of concrete pouring blocks. In this study, optical fibres were embedded throughout the pouring block of the Baihetan arch dam. Furthermore, a temperature gradient monitoring test for surface concrete of the floor and sidewall of the orifice was carried out in the high-temperature season to obtain the actual temperature of the orifice concrete. For the convenience of calculation, the heat flux caused by solar radiation heat is converted into air temperature. The solar radiation heat is regarded as the virtual air temperature increment, which is superimposed with the measured air temperature to form a comprehensive equivalent air temperature. Taking the comprehensive equivalent air temperature as the third boundary condition and considering the influencing factors, such as the pouring schedule, water cooling, and ambient temperature, this study uses finite element software to simulate the temperature field during the construction of orifice concrete. The results show that solar radiation heat has little influence on the concrete temperature in the middle of the pouring block. After the influence of solar radiation heat is considered, the accuracy of the finite element model of the orifice pouring block is significantly improved, and the influence of solar radiation heat on the floor concrete is smaller than that on the sidewall concrete. [ABSTRACT FROM AUTHOR]

This study focuses on the seismic fragility analysis of arch dams. The multiple stripe analysis (MSA), cloud analysis (CLA), and incremental dynamic analysis (IDA) methods are compared. A comprehensive dam-reservoir-foundation rock system, which considers the opening of contraction joints, the nonlinearity of dam concrete and foundation rock, the radiation damping effect of semi-unbounded foundation, and the compressibility of reservoir water, is used as a numerical example. 225, 80, and 15 earthquake records are selected for MSA, CLA, and IDA, respectively. The results show that MSA provides satisfactory fragility analysis, while both CLA and IDA have assumptions that may lead to deviations. Therefore, MSA is the most reliable method among the three methods and is recommended for the fragility analysis of arch dams. It is also shown that the choice of demand level affects the reliability of fragility curves and the effect of the material uncertainty on the fragility of the dam is not significant. [ABSTRACT FROM AUTHOR]

Safety evaluation is an important task to verify the performance of a dam during its service. For an old dam, the material properties vary from the designed value significantly affecting structural performance. This study investigates the effects of material properties of dam concrete and foundation rock on the structural behavior of an old concrete arch dam during operation. The dam safety is evaluated by using a three-dimensional finite element model (FEM). All main loads, such as water pressure, dam self-weight, and thermal load, are considered in the analysis. An existing 54-year-old concrete arch dam, located in a tropical climate region in Thailand, is employed as a case study. The analysis results show that deformation modulus of the foundation, modulus elasticity of concrete, and the variation of reservoir water level during operation are key factors affecting the dam response. With a deformability modulus of foundation and elasticity modulus of dam concrete, which are about 20 GPa and 44.2 GPa, respectively, a good agreement in dam deflections between the analysis and the current monitored data from plumb line equipment can be obtained. It should be noted that the material properties are different from the designed value significantly. Finally, safety evaluation can be properly conducted based on current material properties. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the seismic stability of arch dam abutments is investigated within the framework of the probabilistic method. A large concrete arch dam is considered with six wedges for each abutment. The seismic safety of the dam abutments is studied with quasi-static analysis for different hazard levels. The Londe limit equilibrium method is utilized to calculate the stability of the wedges in the abutments. Since the finite element method is time-consuming, the neural network is used as an alternative for calculating the wedge safety factor. For training the neural network, 1000 random samples are generated and the dam response is calculated. The direction of applied acceleration is changed within 5-degree intervals to reveal the critical direction corresponding to the minimum safety factor. The Latin hypercube sampling (LHS) is employed for sample generation, and the safety level is determined with reliability analysis. Three sample numbers of 1000, 2000 and 4000 are used to examine the average and standard deviation of the results. The global sensitivity analysis is used to identify the effects of random variables on the abutment stability. It is shown that friction, cohesion and uplift pressure have the most significant effects on the wedge stability variance. [ABSTRACT FROM AUTHOR]

Copyright of Österreichische Wasser- und Abfallwirtschaft is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article investigates an inverse problem for variable physical and mechanical comprehensive parameters. A back analysis method based on an improved BFGS (Broyden-Fletcher-Goldfarb Shanno-Newtonian iteration) and AC (adjustment coefficient) is proposed to estimate the physical and mechanical comprehensive parameters of complex concrete arch dam structures. These quasi-viscoelastic variable physical and mechanical comprehensive parameters of concrete arch dam structures are established based on in situ monitoring data and test results. By studying the constitutive model of concrete arch dam structures and the corresponding characterization method of the gradual changes of those parameters, a method utilizing adjustment coefficient is established to determine the initial values of the physical and mechanical comprehensive parameters and an adjoin method combined with BFGS Newtonian iteration method is proposed to inverse the variable physical and mechanical comprehensive parameters of concrete arch dam structures and analyze the variation regulation of these parameters. The proposed inversion analysis method was successfully implemented for the second-highest concrete double curvature arch dam. The results indicate that the proposed method has high precision and strong generalizability.

Summary: Vibration‐based structural health monitoring for arch dams is influenced by various environmental effects, such as water depth and air temperature. These effects do not cause structural damage; therefore, their effects need to be minimized or removed from models. Moreover, arch dams are often located in earthquake‐prone areas; thus, an improved approach is proposed herein to adapt to the aforementioned situations. In this study, an arch dam in China was used for a case study. A long‐term continuous structural health monitoring system was proposed to operate under seismic and environmental excitation. An autoregressive exogenous model was applied for modal identification under seismic excitation. An automatic procedure based on stochastic subspace identification and density‐based spatial clustering of applications with noise was carried out for modal identification under environmental excitation. This study focused on the identification of the first three‐order modes. The seismic events were then analyzed. The natural frequencies before, during, and after seismic events were the same within a certain margin of error. This indicates that earthquakes did not cause major seismic damage to the arch dam. In addition, natural frequencies were continuously identified under environmental excitation. The relationship between natural frequency and water depth forms a quadratic curve, and the modal damping ratio increases with increasing water depth. Finally, this paper presents a random forest model to minimize environmental effects on natural frequencies. After minimizing the influence of non‐structural factors, the natural frequency exhibited a weak increasing trend over time. [ABSTRACT FROM AUTHOR]

Geological conditions play a decisive role in the stability of arch dam engineering, and the asymmetric geological conditions of the abutment have a very negative impact on the safety of the arch dam. This article takes Lizhou arch dam as the research object, and determines that the arch dam is preliminarily affected by the geological asymmetric characteristics. Through the geomechanical model test method, the overload failure test of the Lizhou arch dam was carried out, and the resistance body, the instability deformation of the structural plane of the two dam abutments, and the influence of each structural plane on the dam body are obtained, and the safety factor is determined. According to the test results under the condition of asymmetric foundation of arch dam, for the structural plane which affects the geological asymmetry of the arch dam, the corresponding reinforcement measures are carried out. The feasibility of the reinforcement scheme is verified by the finite element method, and the safety factor after reinforcement is obtained. According to the results, it is suggested that some engineering measures can be taken to reduce the geological asymmetry between the two banks and ensure the safe and stable operation of the arch dam in the future.

The issue of dam type selection is a prevalent challenge in water resource allocation engineering. The site of the Y2 dam in China is suitable for building concrete arch dams and roller-compacted concrete (RCC) gravity dams. To determine which dam type is better in terms of construction progress, this paper proposes a multiattribute decision-making method based on construction simulation. First, the construction characteristics of concrete dams are analyzed, and the construction simulation systems for arch dams and gravity dams are developed based on construction simulation theory. Then, for each dam type, the initial construction schemes are used as the input of the simulation systems, and attribute values of construction progress are output. Secondly, a multiattribute decision-making method is used to select the typical scheme of each dam type from these initial schemes. Finally, the simulation results of the typical schemes for the arch dam and the RCC gravity dam are compared, to determine the optimal dam type for the Y2 dam. The results show that for the Y2 dam, the construction period of the arch dam is 34 months, and that of the RCC gravity dam is 28 months. From the perspective of construction progress, the Y2 dam type should select the RCC gravity dam. Compared with similar dams that have been built, it is concluded that the simulated progress result conforms to the current actual construction level, which also verifies the correctness of the calculation results and the reliability of the construction simulation.

In this study, a fast partitioned solution method that considers contact nonlinearity and local material nonlinearity based on the partitioned finite element and interface element method is proposed. Combined with the local failure characteristics of hydraulic structures such as arch dams, the stiffness matrices of the linear and nonlinear regions of the structure are decomposed to reduce the size of the overall stiffness matrix. Furthermore, in the nonlinear iteration, only the stiffness matrix of the nonlinear partition is modified, thereby reducing the calculation amount of the overall solution and improving the solution efficiency. The results show that our proposed method exhibits improved solution speed and stability while achieving the same solution accuracy. [ABSTRACT FROM AUTHOR]

Modal analysis, aiming at estimating modal characteristics such as natural frequencies and mode shapes, is fundamental for studying the dynamic behaviours of a structure. This paper presents a modal analysis of an arch dam using three different techniques. The reference one is based on the statistical analysis of the ambient vibration data collected from the dam crest. The two other approaches are both numerical but with different methods (fluid‐element and Westergaard) for the modelling of the reservoir and its interactions with the dam. By applying the three techniques to the studied dam and comparing their results, it is demonstrated that: (1) analysing the ambient vibration data through an operational modal analysis method is able to extract the dam modal characteristics; (2) the fluid‐element method is effective for arch dams since the first 10 natural frequencies can be accurately predicted once the material parameters are calibrated on the first three modes; and (3) the Westergaard method, a technique with only additional masses, produces significantly under‐estimated frequencies for the first few modes if same parameters are used as the fluid‐element method; the underestimation can be corrected for several modes by using a higher stiffness parameter but the required value is unrealistic for the case study. Furthermore, a modified Westergaard method is introduced in this paper by using a reduced added‐mass coefficient. This method, once the coefficient is calibrated on the 1st mode, is able to well predict the partially coupled modes as illustrated with the case study of the Saint‐Guérin dam. [ABSTRACT FROM AUTHOR]

Arch dams are typically built in the mountain and gorge regions with complex terrain. In the current engineering practice, foundation models are commonly simplified as the half-space with the canyon of regular geometry. The complex topography conditions above the dam crest are neglected. This study investigates the effect of realistic valley topography on the dynamic response of arch dams. The direct finite element method is generalized and applied to the dam-reservoir-foundation system with realistic valley topography. The input ground motions are transformed into the effective earthquake loads at the truncated boundaries by performing several dynamic reaction calculations using one-dimensional (1D) and two-dimensional (2D) auxiliary finite element models. The effect of valley topography on the seismic response of the Baihetan arch dam is evaluated as a case study. Results indicate that the valley topographic irregularities significantly influence the dynamic responses of the arch dam, including relative displacement and stress distribution. Notably, the valley topography effect on the seismic response of arch dams depends on the incident ground motions and is hardly predicted in advance, demonstrating the necessity to account for the realistic topography conditions. • The direct finite element method is generalized to realistic topography sites. • Procedure to obtain the seismic forces for realistic topography sites is presented. • The effect of valley topography on the seismic response of arch dams is analyzed. [ABSTRACT FROM AUTHOR]

• An effective procedure to swiftly acquire seismic response of arch dams soon after an earthquakes • An integrated automation process spans from acceleration data acquiring to results presenting. • The application to an engineering project validates the satisfactory accuracy of the procedure. • Different usage conditions verify the wide applicability of the procedure. • The procedure has potential to offer valuable insights for similar analyses in engineering practice. The seismic safety of arch dams has long been a focal point of research. Due to the complexity of modeling and computation, analyzing the seismic response of arch dams using traditional finite element methods requires a considerable amount of time. In the event of a sudden earthquake, it is challenging to quickly obtain stress analysis results or conduct a safety assessment. To address these issues, a rapid and automated analysis procedure is proposed in this paper, providing seismic response of arch dams within hours after an earthquake. The procedure includes a pre-processing program, a computing program EACD-3D-2008, and a post-processing program, achieving a fully automated process from generating non-uniform earthquakes to analyzing dam dynamic responses and visualizing computation results. As a case study, the 294.5 m high Xiaowan arch dam in southwest China is analyzed, which is equipped with strong motion instruments that have recorded several small earthquakes. The case study revealed that accounting for the non-uniformity of the earthquake significantly improves simulation results, with maximum principal stresses typically occurring near the dam-foundation rock interface. Additionally, the procedure effectively compensates for missing data, allowing for the successful supplementation of the missing acceleration records. For stronger earthquakes, high-stress regions are clearly displayed in the result visualization, providing an effective reference for safety assessment. The case study validated the accuracy and wide applicability of the procedure, demonstrating its potential to offer valuable insights for similar analyses in various engineering projects. [ABSTRACT FROM AUTHOR]

Dam behavior prediction is a classic problem in the monitoring of dam structure. To obtain accurate results, different researchers have established various models. However, the models of predecessors rarely studied the nonlinear characteristics of dam displacement data and the abnormal values of monitoring data. It means that abnormal values will contaminate data set, and consequently reduce the accuracy of model predictions. In this article, an improved Random Forest (RF) model was proposed for analyzing dam displacement prediction and was coupled with a sliding time window strategy. The proposed model is developed by the following steps. First, for the purpose of alleviating the time-lag effect of impact factor phenomenon, a sliding time window strategy was introduced into the RF model to improve the time sensitivity. Second, aiming to determine the hyperparameters, Grid Search (GS) was introduced into RF model to improve the global optimization ability. This article takes masonry arch dam in China as an example, and adopts the horizontal displacement recorded by Global Navigation Satellite Systems (GNSS) as the research object. The accuracy and validity of the proposed model are verified and evaluated based on the evaluation criteria. The simulation results demonstrate that the proposed model could capture the long-term characteristics and provide better prediction based on short-term monitoring data. It also has strong robustness on the abnormal data series, has simpler structures and less parameters, and requires less time for model training, so it can be a potential tool for actual monitoring tasks.

For the first time, low-heat cement was used in the entire dam section of Baihetan Dam, but the thermal properties of low-heat cement under construction conditions have yet to be fully studied. The thermal parameter values of low-heat cement may differ significantly from the indoor test values or specification values due to factors such as ambient temperature, cooling through water, and surface insulation under actual site conditions. Therefore, in order to obtain more accurate values of the thermal parameters, the hybrid swarm intelligence algorithm and field temperature monitoring data are used to identify the concrete thermal parameters of Baihetan arch dam. To overcome the shortcomings of Particle Swarm Optimization (PSO) that is easy to fall into local optimum and Artificial Bee Colony (ABC) that has insufficient development ability, an Integrated Algorithm Based on ABC and PSO (IABAP) is established. Through eight different test functions and comparing with other different algorithms, it is verified that the IABAP algorithm has certain advantages in terms of convergence speed and accuracy. Considering the influence of ambient air temperature and multi-shift water cooling during construction, IABAP is applied to the inversion of concrete thermal parameters with the same strength, different strength and different gradation of Baihetan arch dam. The computational results show the good performance of the IABAP algorithm in engineering applications on the one hand, and the applicability and reliability of the parameter inversion on the other hand, which can meet the accuracy requirements of practical engineering. At the same time, the conjecture that the thermal parameters are consistent in adjacent dam sections was verified by bringing the thermal parameters into the adjacent dam sections for simulation calculations. Finally, the experimental values of thermal parameters of low-heat cement concrete of Baihetan Dam were compared with the inverse values to analyze the change law of thermal parameters, and it was found that the final adiabatic temperature rise of low-heat concrete was smaller than the indoor experimental values during the actual construction. [ABSTRACT FROM AUTHOR]

To establish the correlation between monitoring indexes and damage indexes for the purpose of rapid assessment of dam damage, this paper takes the Baihetan arch dam as an example and establishes a three-dimensional finite element model for dynamic analysis. Focusing on the crown cantilever, the study analyzes the correlation between different monitoring indexes and damage indexes using DCCA correlation coefficient, and constructs a Random Forest prediction model based on time history information of indexes. Using this model, the paper predicts the volume ratio of damage for the crown cantilever over time and its maximum value, comparing the results with those obtained from a model based on maximum value information, through error analysis. The results of the correlation analysis indicate a close relationship between the increase in the maximum upstream displacement, maximum upstream acceleration, and the widening of the transverse joint opening width, and the development of damage in the monolith. The error analysis results demonstrate that the prediction network established based on time history information performs well in both point prediction and interval prediction. The research presented in this paper provides a feasible approach for the comprehensive assessment of real-time seismic damage in arch dams. • Quantitative correlation studies of indexes were conducted by DCCA coefficient. • The acceleration, displacement and opening width of transverse joints closely associated with the increase of monolith damage. • Establishing a prediction model for real-time and rapid evaluation of the monolith damage. • Damage prediction model based on time history data has good prediction accuracy and precision. [ABSTRACT FROM AUTHOR]

The deformation characteristic of the arch dam can directly reflect its service performance, which can be analyzed on the basis of the dam deformation field. However, restricted by the limited number of dam monitoring points and the inhomogeneity of materials, an accurate measurement of arch dam deformation field is difficult to estimate by using the existing common methods, such as the spatial interpolation methods and the finite element method (FEM). With the aim of ensuring arch dam structure safety, the ordinary kriging interpolation method, combined with FEM, is proposed for arch dam deformation field estimation, in this study. Given the inversion of the computation parameters of the arch dam, FEM is used to calculate the basic arch dam deformation. Subsequently, the ordinary kriging interpolation method is introduced to estimate the spatial variance deformation at each point of the arch dam. One superhigh arch dam in China is selected as a case study; two additional methods are introduced as comparisons that are based on a numerical experiment and the actual monitoring data. The experimental results show that the proposed method considerably improves the accuracy and computational efficiency of the arch dam deformation field estimation and that it is of great practical importance for characterizing the deformation behavior of arch dams.

Arch dam abutment stability is regarded as a prominent part of designing concrete dams. In the present study, the seismic stability of the rock wedges in the foundation of the concrete arch dams is studied using limit state and finite-element methods. For this purpose, a double-curvature arch dam (the Bakhtiari dam), is taken into consideration. Each abutment has six wedges. The finite-element model (FEM) includes the dam, reservoir, wedges, and the rest of the foundation. The dam abutment seismic safety is analyzed using the time history analysis along with the Londe method. Subsequently, the wedges in the proximity of the critical state are identified. Afterward, the analysis of the critical wedges' joints has been conducted via FEM, and the damage propagation in the dam body has been investigated. Moreover, the effects of the grout curtain efficiency, hazard level, and foundation flexibility on the nonlinear behavior of the arch dam with integrated foundation and foundation with joints are scrutinized. The outcomes reveal the remarkable effect of joints considered in the foundation on the dam behavior. [ABSTRACT FROM AUTHOR]

The article presents a method for monitoring the natural frequencies of HPP dams according to continuous seismic observations. The object of the research is the largest arched dam in Russia, the Chirkey HPP located in the Caucasus. If damaged, it could cause great loss of property and human life, but disasters can be minimized by using effective dam structural health monitoring. The study for changes in the natural frequencies of engineering structures is one of the most common methods of remote control over their structural health. However, the determination of values of natural frequencies of huge concrete dams is a very difficult procedure due to their have complex construction. Moreover, interpretation of changes in the natural frequencies values is difficult due to the significant influence of the water level in the reservoir. Consequently, at the initial stage, we performed a detailed study of the natural oscillations of the dam using the method of coherent restoration of the standing wave fields with the definition of both the natural frequencies of the structure and their modes. They were conducted twice at the minimum and maximum upstream level and for the first time highlighted the features of seasonal changes in the full field of standing waves. The normal modes were determined that are present in oscillations at different upstream levels and which frequencies can be detected continuously from the records of seismic equipment. The series of frequency changes during the year are calculated. For the first time we established that, frequency changes are by 5 to 11 days behind reservoir level changes and assumed that relaxation processes of the dam body and / or its base cause the delay after the upstream level changes. We calculated dependencies for predicting the frequency values from the reservoir level, taking into account the delay time. As a result, we proposed an approach for monitoring of the dam structural health based on a comparison of the observed natural frequencies with the predicted ones. The developed method can be applied to monitor the structural health of concrete dams of other HPPs.

The aim of this study is to present an evaluation of the thermal load effects on the behavior of a concrete arch dam in Thailand. A Three-Dimensional Finite Element model for the thermal transient analysis was implemented to determine the thermal distribution in the dam body. Environmental conditions, such as reservoir water temperature at all depths, ambient temperature, and solar radiation were considered in the analysis. Then, structural analysis was conducted to evaluate deflections and stresses in the dam caused by the temperature profile. The thermal analysis results indicated that the upstream face is strongly affected by reservoir water temperature, while air temperature and sunlight mostly affect the downstream and crest faces. The solar radiation increases the concrete surface temperature by about 2 ℃ to 7 ℃ above the ambient temperature and causes nonuniform temperature distributions on the dam faces. Though prior literature shows significant effects of seasonal temperature variations on dam behavior, the structural analysis results in this paper show that the thermal loads contribute very little to the stresses and deflections of a dam in Thailand.

In view of a high arch dam, first of all, the linear elastic finite element method was used to analyze how the gravity loading method affected the overall stress field distribution of the dam. Then it considered the applying process of hydrostatic pressure and temperature loads on arch dam stress, the influence of the hydrostatic pressure was little to the stress and temperature had a greater influence to the temperature drop to dam stress. In the end, the nonlinear finite element method was used to analyze the impact of the construction process on the plastic area of the dam and the size of the plastic strain and it had to be the most damaging to the dam in the nonlinear model. [ABSTRACT FROM AUTHOR]

This paper proposes an improved dynamic stability analysis for abutment of dam (IDSAM) by combining interface boundary element with partitioned finite element (PFE-IBE). The total yield of the control area is taken as the instability criterion, and the area is made up of contact point pairs controlling the structural surface. The full structural surface yield state of the structural surface of the dam abutment rock mass was taken into account. The strength reduction coefficient corresponding to the full structural surface yield was taken as the safety factor of dam abutment stability. In this way, the damage of the structural surface can be reflected more accurately and intuitively, eliminating the impact of human factors on the valuation of the safety factor. Three calculation methods are used to evaluate the abutment stability of the Shapai Arch Dam, including pseudo-static method, the combination between finite element method and rigid body limit equilibrium method, and the proposed IDSAM. The comparison of results shows that the dam abutment safety factor obtained by IDSAM (left 2.4, right 3.0) ranges between those obtained by pseudo-static method (left 2.116, right 2.945) and finite element rigid body limit equilibrium method (left 2.429, right 3.182). Hence, the safety factor acquired by our method is rational. Considering the nonlinear characteristics of rock mass discontinuity, IDSAM reflects the operating state of the arch dam, shedding new light on the evaluation of aseismatic safety. [ABSTRACT FROM AUTHOR]

Summary: The deformations of ultrahigh arch dams can comprehensively indicate the dynamic variations of their structural behavior to judge the normal or not for timely discovering anomalies. First, the panel data features on the deformation behavior are extracted to effectively indicate the overall structural evolution of the Jinping I arch dam combing with the time series and the cross‐section series. Afterwards, a regression panel model (RPM) on the multi‐dimensional variables is proposed to model the deformation panel data consisted of multi‐monitoring points synchronously. Subsequently, an innovative functional relationship between the measured values and the real‐time risk probabilistic function is established due to the RPM estimation accuracy. In order to estimate the risk probability of the whole arch dam, the Copula function is used to build a multivariate joint probability distribution function to indicate the correlation among the random variables. The proposed methods are validated by an application on the Jinping I arch dam to evaluate its risk probability, which explores a novel approach for the arch dam safety assessment. [ABSTRACT FROM AUTHOR]