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First, prior distribution of the mechanical parameters of arch dam body and its nearby mountain rock mass was determined according to the meso-modelling of dam concrete and test data of its nearby mountain rock mass, and a finite element model of the arch dam and its nearby mountain was established. Based on Bayesian theory, random inversion objective function was established. Afterwards, inversion analysis of mechanical parameters was conducted with Differential Evolution Adaptive Metropolis (DREAM(SZ)) on the basis of Markov chain random theory, for the inversion of random distribution parameters of the elasticity modulus of dam concrete and overall deformation modulus. This method was applied to some high-arch dam project, and it was verified to be effective by the results.

Gallery cracks occur commonly in concrete dams, but their cracking mechanism has yet to be effectively revealed. In this paper, the actual temperature, stress change history and cracking process of a gallery area were uncovered, based on the safety monitoring data of cracks in a super-high arch dam. In addition, the basic development and change laws, as well as the corresponding cracking mechanism, were analyzed, and the real causes and influential factors of cracks at the site were revealed, which will provide a reference for the prevention of cracks in similar projects in the future.

Seismic safety of concrete arch dams are of significant concern as it may exhaust the social and economic wellbeing of humanity. Dam –Foundation and Dam- Reservoir interactions greatly influenced the dynamic behavior of arch dams. Under earthquake excitations, geological features of dam systems behave rigorously. Therefore, the evaluation of concrete arch dam involves the comprehensive inquisition of responses from the far–field and free-field boundaries. Models developed so far with simplified assumptions explicit the need for the identification of factors in the analysis and design of dam structures. Traditional analytical methods result in over-rigid dam structures that can upshot over-estimated stresses and strains. In the earlier researches, the foundation rocks were assumed massless. It easily simplifies the uncertainty in inertia and damping but gives inaccurate solutions. Thus, approximations in the dam-water-foundation system by ignoring the mainframe parameters play a crucial role in analyzing structure. Finite Element Method with relevant factors under consideration brings up the solution with most negligible errors. FE model calibrated with appropriate parameters will predict the exact behavior of dam structures under seismic excitations. This paper presents the review of research conducted on the concrete arch dam focusing on dam-foundation, dam–water interactions, massed and massless foundation, water compressibility, thermal variations, spatial variations in the ground motion, etc.

The main aim of structural safety control is the multiple assessments of the expected dam behaviour based on models and the measurements and parameters that characterise the dam’s response and condition. In recent years, there is an increase in the use of data-based models for the analysis and interpretation of the structural behaviour of dams. Multiple Linear Regression is the conventional, widely used approach in dam engineering, although interesting results have been published based on machine learning algorithms such as artificial neural networks, support vector machines, random forest, and boosted regression trees. However, these models need to be carefully developed and properly assessed before their application in practice. This is even more relevant when an increase in users of machine learning models is expected. For this reason, this paper presents extensive work regarding the verification and validation of data-based models for the analysis and interpretation of observed dam’s behaviour. This is presented by means of the development of several machine learning models to interpret horizontal displacements in an arch dam in operation. Several validation techniques are applied, including historical data validation, sensitivity analysis, and predictive validation. The results are discussed and conclusions are drawn regarding the practical application of data-based models.

Safety evaluation is an important task to verify 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 behaviour 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 designed value significantly. Finally, safety evaluation can be properly conducted based on current material properties.

Interferometric synthetic aperture radar (InSAR) is a cost-effective method for displacement measurement at dams and reservoir banks, and is especially relevant for structures without embed...

To ensure the safety assessment of dam during the construction period and further water storage period, the deformation characteristics and mechanism of valley relating to Wudongde hydropower project were analyzed based of the monitoring and numerical simulation of valley deformation in the early and present stage. The evolution process of displacement near the dam area was calculated by numerical method, as well as the deformation amount of valley in 2016~2018. The simulation results and deformation monitoring results were compared, and the space-time distribution law and initial driving factors of valley deformation behind the dam were summarized. The results show that the width of valley behind dam changes slowly, and the width of valley shows a tendency of contraction. The deformation of the left bank is larger than that of the right bank, and deformation of the part with high elevation is generally larger than that of the part with low elevation. The shrinkage deformation of valley of the tailgate is the largest. The disturbance of human engineering activities such as construction and excavation will accelerate the rebound and rheological deformation of rock mass in the dam area, and make the original rock mass shrink and deform towards the river valley.

The safety of a high concrete arch dam should be rapidly diagnosed from different angles. Displacement is an actual comprehensive reflection of the arch dam, and it is very important to diagnose the overall deformation behaviour by displacement-based mathematical monitoring models. In this article, based on the spatial association validation of the measured displacement of two high arch dams by the empirical orthogonal function decomposition and the Pearson correlation analysis, two spatial association–considered mathematical models were proposed for the dam displacement of multimonitoring points: one model for the long-term balanced relationship and one model for the short-term fluctuation. To diagnose the abnormality of the dam long-term spatial association, each displacement time series of the multimonitoring points on the dam body with strong spatial associations was decomposed by wavelet multiresolution analysis, and the decomposed high-frequency components, which had the same periodicity as the causal factors of the reservoir water level or air temperature, were determined to establish the cointegration monitoring model. The second model was a combination prediction model, with two sub-models established from the modelling angles of the hydraulic, seasonal and time causal factors and the adjacent point displacement factors, and this second model was mainly used for identifying dam short-term local abnormal deformation behaviour. Engineering examples show that the deformation behaviour of an arch dam under normal conditions has strong spatial associations. The two proposed models have high accuracy and interpreting ability and can effectively reduce the number of needed monitoring models.

Abutment movement that induces a reduction of the valley width in the periods of initial impoundment has been observed in a few high arch dams. In this article, the effect of the abutment movement ...

Dams are singular infrastructures whose safety assessment requires mathematical models for predicting its behavior and detecting anomalies. Here, we develop an approach based on random forest regression for dam displacement prediction. Random forest regression is a non-parametric statistical technique that can deal with non-linearities and does not need assumptions regarding relationship between predictors. Inputs to the model are the water level in the reservoir, time, and concrete temperature, and the outputs –predicted variables– are movements at the desired points. Since concrete temperature is only available at those points where thermometers are placed, we compute the thermal field at any point of the dam through a one-dimensional deterministic model. Our thermal model accounts for solar radiation, shading, night and evaporative cooling, convection with the air, and long wave radiation exchange. We assess the performance of our model by comparing its estimates with recorded data at a case study, an arch dam located in Algeria, and with outputs computed by two widely used statistical models and an artificial neural network model. Our model provides satisfactory predictions and improves the results of the other models. Our approach is a powerful tool for analyzing dam displacements and incorporates a rigorous evaluation of thermal loads. It emerges as a good alternative for practitioners and stakeholders.

On December 2, 1959, the Malpasset arch dam in southeast France suddenly failed, flooding the valley down to the sea, causing huge destruction and more than 400 casualties. Built from 1952 to 1954 for water supply and irrigation, filling of the reservoir was delayed five years and the failure occurred following a flash flood of the river the dam was closing. Post failure studies and expertise during a trial revealed poor field investigations on a micaschist rock foundation crisscrossed by faults, and poor management of construction of the structure. The failure was ascribed to uplift, moving a rock dihedron defined by a conspicuous fault and a tear along foliation. This paper shows that, in addition to the many traps listed by previous investigations (mostly geological and geotechnical), the human and organizational factors can also shed a new light on this catastrophe. Keeping lessons from Malpasset alive and increasing the knowledge about this case is relevant since worldwide, after the catastrophe, not only did new regulations on dams appear but also both fields of geological engineering and rock mechanics were developed. Thus, consciously or not, every geological engineer or rock mechanics specialists is somehow, a descendant of this case.

Due to an increased need in hydro-electricity, water storage, and flood protection, it is assumed that a series of new dams will be build throughout the world. The focus of this paper is on the non-probabilistic-based design of new arch-type dams by applying means of robust design optimization (RDO). This type of optimization takes into account uncertainties in the loads and in the material properties of the structure. As classical procedures of probabilistic-based optimization under uncertainties, such as RDO and reliability-based design optimization (RBDO), are in general computationally expensive and rely on estimates of the system’s response variance, we will not follow a full-probabilistic approach but work with predefined confidence levels. This leads to a bi-level optimization program where the volume of the dam is optimized under the worst combination of the uncertain parameters. As a result, robust and reliable designs are obtained and the result is independent from any assumptions on stochastic properties of the random variables in the model. The optimization of an arch-type dam is realized here by a robust optimization method under load uncertainty, where hydraulic and thermal loads are considered. The load uncertainty is modeled as an ellipsoidal expression. Comparing with any traditional deterministic optimization method, which only concerns the minimum objective value and offers a solution candidate close to limit-states, the RDO method provides a robust solution against uncertainty. To reduce the computational cost, a ranking strategy and an approximation model are further involved to do a preliminary screening. By this means, the robust design can generate an improved arch dam structure that ensures both safety and serviceability during its lifetime.

The overall mechanical behavior of the structure of an arch dam is comprehensively reflected by the vibration modal information included in measured vibration response. Hence, the results obtained from inverting material parameters based on measured vibration data are often superior to those based on static monitoring data. In this study, a dynamic inversion method for the material parameters of a high arch dam and its foundation is proposed on the basis of the measured vibration response. First, an arch dam prototype test is conducted to obtain the measured dynamic displacement response as input. Then, a stochastic subspace identification method based on singular entropy is formulated to determine the modal parameters. Second, a dynamic elastic modulus (DEM) with a great influence on the modal parameters is selected as the material parameter to be inverted. Then, a response surface model (RSM), which reflects the nonlinear relationship between the material and modal parameters of each zone, is constructed. Latin hypercube sampling is used to generate the sample library of the DEM. The RSM is fitted by modal parameters calculated on the basis of the arch dam finite element model (FEM) and is applied to replace the FEM. Finally, the optimization mathematical model of the inversion of the DEM is established. Then, the objective function is optimized through a genetic algorithm, and the optimal combination of the DEM in each zone is inverted. The modal parameters of the arch dam calculated by inversion results are consistent with those measured by variation law and values. Therefore, the inversion results are reasonable and reliable. This method provides a new idea for determining the material parameters of a high arch dam and its foundation during the operation period.

The environmental temperature is the key factor for cracking failure of mass concrete structures in severely cold regions. In this paper, field test and numerical calculation of long term insulation are carried out to prevent thermal cracks, and ensure the durability and safety of concrete arch dam. Firstly, an equivalent simulation element for concrete-polyurethane composite structure and its calculation method is proposed, based on the equivalence idea of heat emission coefficient for concrete layer and surface insulation layers with different thickness. Secondly, field tests are demonstrated on an 87.5 m height concrete gravity-arch dam, named Xianghongdian dam, from January 1, 2001 to May 30, 2017. Distributions laws, change laws of temperature field and horizontal displacement of the dam, before and after setting polyurethane insulation layer, are compared deeply. Then, the insulation effects of different thicknesses of foamed polyurethane layer are investigated upon the establishment of a FEM model of a concrete arch dam in northwest China. Consequently, stress fields under different broken conditions of polyurethane insulation layer with different typical temperature loads in severely cold region are calculated and analyzed. The results show that the polyurethane insulation layer generally decreases the temperature change range of concrete dam body over 30% in all conditions and even 90% at some locations. Accordingly, the horizontal displacement component, caused by dam temperature, decreases greatly from 10.80 mm to 2.34 mm and its contribution ratio to yearly horizontal displacement decreases from 75.11% to 36.23%. The insulation layer broken would result in a sharp increase of tensile stress of the corresponding area, with the combination influences of low temperature and cold wave. Under small broken condition, the tensile stress increases from 3.69 MPa to 7.57 MPa among broken area; while under large broken condition, the tensile stress increases to 8.68 MPa, which exceeds the maximum tensile stress of concrete material. In this case, a cracking failure of concrete structure would happen. As the dam concrete is an insulation material in some degree, the stress filed doesn’t change a lot in areas the insulation layer is unbroken.

To improve concrete crack prevention performance for high concrete dams, several studies have shown that the addition of MgO-type expansive can compensate for shrinkage of concrete and prevent concrete from cracking. In this paper, the Autogenous Volume Deformation (AVD) process of MgO concrete as a function of curing age, temperature and MgO content has been presented. The objective of this paper is to develop a hyperbolic expansive model, in which the parameters are developed and validated for the modeling of AVD process of MgO concrete and compared with Shu-hua Liu’s method. In addition, the correction coefficients have been proposed and the relationships between the model parameters and MgO content have been also introduced. The model parameters were obtained based on the experimental data under laboratory conditions for the AVD process. Then the final equation of the hyperbolic expansive model is determined by the MgO content, the curing temperature and time. The calculation results are then compared with the measured data; and the reasonably good correlation between simulated and measured results indicates that the selected values of Gpre, c(T), and the relationships between model coefficients, MgO content, and temperature, are almost perfect. It will enhance the design reliability of the Linxihe RCC arch dam project and others.

Simulation of the infinite foundation is a key issue in the seismic response analysis of high dams. This paper studies how the major characteristics of foundation models influence the nonlinear dynamic response of arch dams when the radiation damping effect is taken into account. The nonlinear dynamic responses of the 217 m high Yebatan arch dam under construction in China is performed as a numerical example. Several key factors, including truncated size, material damping and non-uniformity of the foundation, are analyzed comprehensively. The results show that the material damping and the size of the foundation affect the dynamic response of the dam when the incident wave method is used. Neglect of the material damping of the foundation is proposed to solve this problem, and its rationality is verified. In addition, the results show that the realistic non-uniformity of the foundation should be considered in the earthquake response of arch dams.

During concrete dam construction, concrete temperature monitoring and control is key to ensuring dam concrete quality and construction safety. In this study, a 2D thermal field restructuring method relating to the Kriging temperature interpolation is proposed. Based on dam site monitoring data of distributed optical fiber, the results indicated that the proposed restructuring method can be applied to effectively and quickly obtain 2D real thermal field. The evolution law of thermal field in early ages and temperature differences of concrete blocks based on the thermal field data are obtained. It also can be concluded that the proposed restructuring method could help obtain accurate and reliable restructuring monitoring data. Keywords: 2D thermal field, Restructuring method, Distributed optical fiber, Kriging, Concrete dam

The paper presents the design and static analysis of a high arch dam. A feasibility study was conducted on the dam in the 90s and a preliminary layout was designed. However, the dam’s construction phase has been never started. In this paper, the design and layout of the dam under consideration are in accordance with the US manuals for the design of arch dams. The structure’s three-dimensional model was entered into the program SAP2000 and three-dimensional solid finite elements were used to discretize the model. This paper considers the hydrostatic pressure of the water reservoir and concrete self-weight. The analysis was performed for both the maximum and the minimum designed water level and for the case when the reservoir is empty. Special attention is given to the boundary conditions of the dam at its abutments and foundation. The results show that the planned layout is good for the dam’s construction. The arch dam’s curve transfers the loads to the abutments. The significant role of the foundation rigidity and the reservoir water level in the stress distribution and nodal displacements within the arch dam is observed.

This paper aims to define the non-linear response for concrete arch gravity dams, considering seismic actions as main external destabilizing actions. The plastic degradation theory has been used to define the reduction of the elasto-plastic modulus during the hysteretic cycles. The parameters to apply the model are obtained from the literature and numerical analysis. In this sense, working with a reduction of the elasto-plastic modulus is useful to define the displacement of the structure. The seismic input has been obtained from probabilistic and deterministic seismic hazard analyses. For that, a series of several earthquakes have been chosen to perform the time–history analysis. The response of the structure blocks under four earthquakes has been made using a step-by-step direct integration. An application to Rules Dam has been made to test the method. Results of the seismic analysis provide several specific accelerations for concrete arch gravity dams. Results of the structural show that in 2D analysis the maximum non-linear dam displacements reach value up to 27 cm, whereas for 3D analysis they reach up to 7 cm. Moreover, these cyclic displacements produce several accumulations of plastic deformations and cracks.

The natural frequencies of the Chirkey arch dam extracted from the microseismic noise by coherent reconstruction of standing-wave fields are analyzed. It is for the first time that the natural frequencies of a dam were determined and its modes of vibration were detailed after a natural experiment. The results can be used as input data for monitoring the dam conditions.

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

The Baihetan super-high arch dam is the largest hydropower station in the world under construction. Columnar jointed basalt (CJB) is widely distributed at the Baihetan dam foundation, and the many closely spaced joints pose potential risks on the unloading quality of the foundation surface. In this study, typical unloading cracking and relaxation features of CJB based on field survey and the acoustic wave test are revealed during foundation excavation. Considering the large-scale joints in category-I CJB, an equivalent continuum constitutive model was proposed for describing anisotropic deformation and the unloading relaxation modes and the mechanism of columnar joints are further analysed. Both monitoring and numerical results show that: 1) the unloading behaviours include shallow relaxation of columnar joints and combined rebound deformation of columnar joints and shear belts; 2) the relaxation range of columnar joints mainly occurs at the shallow foundation surface with the maximum depth of 3~4 m, and the relaxation degree is obviously exaggerated owing to the sliding of shear belts; 3) the unloading relaxation mode at the shallow foundation mainly belongs to rebound deformation and relaxation of oral joints. The tensile failure occurs in steep joints, and both tensile and shear failure occur in gentle joints. The proposed model can be applied to effectively simulate the unloading relaxation processes of dam foundation excavation.

The probabilistic risk of arch dam failure under thermal loading is studied. The incorporated uncertainties, which are defined as random variables, are associated with the most affecting structural (material) properties of concrete and thermal loading conditions. Karaj arch dam is selected as case study. The dam is numerically modeled along with its foundation in three-dimensional space; the temperature and thermal stress distribution is investigated during the operating phase. The deterministic thermal finite element analysis of the dam is combined with the structural reliability methods in order to obtain thermal response predictions, and estimate the probability of failure in the risk analysis context. The tensile overstressing failure mode is considered for the reliability analysis. The thermal loading includes ambient air and reservoir temperature variations. The effect of solar radiation is considered by an increase in the ambient temperatures. Three reliability methods are employed: the first-order second-moment method, the first-order reliability method, and the Monte-Carlo simulation with Latin Hypercube sampling. The estimated failure probabilities are discussed and the sensitivity of random variables is investigated. Although most of the studies in this line of research are used only for academic purposes, the results of this investigation can be used for both academic and engineering purposes.

The aim of this study is to propose a cracking analysis method for a super high arch dam based on fracture toughness. A local cracking problem of the Xiluodu super-high dam is first introduced in detail in terms of the related horizontal cracking propagation risk during the construction period and the effect on overall stability during the operational period. An engineering procedure is then proposed to define the cracking stability and analyze the effects of crack repair for super high arch dams. This procedure is based on comparing the stress intensity factor KI, obtained using a 3D fracture mechanics approach and numerical simulation, with the experimentally obtained fracture toughness of site-cast fully-graded concreteKIC. The three cracking states of stability, critical stability and crack propagation are defined by the analysis method. The proposed engineering procedure is then applied to predict the cracking risk and effect to the Xiluodu arch dam at elevation level (EL) 358.8–361.8 m. The predictions on cracking stability correlate well with field site deformation monitoring evidence.

The Dagangshan high arch dam , located in the area with complicated geological conditions and extremely high seismic intensity in Southwest China, has received substantial attention worldwide. Before the impoundment of the reservoir, continuous deep transverse cracks were observed in the low-elevation galleries of the arch dam. To investigate crack formation and propagation in the galleries of the high arch dam, microseismic monitoring and 3D finite element analysis of the galleries were performed during the filling process. The microseismic monitoring system was installed in the foundation gallery and the drainage gallery to detect microcracks around the galleries of the arch dam. The background stress field for crack formation and propagation in the galleries was studied based on 3D finite element modelling . The results indicate that the self-weight of high arch dam produces excessive circumferential tensile stresses at the arch crown of the galleries near the dam heel before impoundment, which is the cause of crack formation in the galleries of the Dagangshan high arch dam. As the impounded water level rises, the tensile stresses and the microseismicity in the galleries near the arch dam heel transfer to the galleries close to the arch dam toe, and the cracks in the galleries near the dam heel would not propagate further but be closed. However, cracking may occur in the gallery close to the dam toe if its microseismicity continues increasing. The conclusions have significant implications for reinforcement and operation of the galleries in similar high concrete arch dams.

Geomechanical model test is an important way to analyze the safety of high arch dams. The traditional monitored displacements and stresses are difficult to interpret the internal failure process of dams and foundations. Acoustic emission(AE) technique was used in the geomechanical model test of arch dam to analyze its internal failure. AE 2D planar locating technology for arch dams and signal parameter analysis method were studied and applied to an arch dam geomechanical model test. The failure process of the dam body and foundation was revealed. The left dam heel of the arch dam model cracked first, continuing to expand to higher elevation along the left abutment with the increase of overload times, and the horizontal crack penetration leaded to the ultimate failure of the dam body. Safety factors for initial crack, nonlinear deformation and ultimate bearing capacity of the arch dam model had been clearly obtained based on AE technique. The results of AE analysis coincided well with the actual failure condition. So it is confirmed that AE technique is effective for geomechanical model test, and it has a bright prospect to be used in situ test of arch dam.

It is widely accepted that plastic optical fibers will have broad application prospect in the field of structural health monitoring because the fiber is not easy to break like silica optical fibers and it also has excellent characteristics such as large diameter, good toughness, high plasticity and low cost. In order to monitor the location, width and direction of cracks in concrete dam, quantitative crack monitoring method of concrete dam based on POF-OTDR is studied theoretically and experimentally. Firstly, mathmatical model of quantitative crack monitoring is established through a lot of model tests. Then double-POF crack monitoring method is presented and validated experimentally after analysing possible layout methods. Based on this interpretation, a reasonable POF network layout scheme for crack monitoring is proposed. Finally, network structure for a concrete arch dam is discussed based on numerical calculation.

Mastering the real temperature distribution of the concrete dam is the basis for solving the problem of temperature control and crack prevention. In this paper, Distributed Temperature Sensing (DTS) technology was applied to temperature monitoring of a high-arch dam under construction in southwest China. In order to obtain a more comprehensive temperature distribution of the dam, optical fiber layout principles for arch dams were studied, and horizontal and vertical optical fiber layout schemes were first proposed according to these principles. The real temperature variation processes of the dam were obtained in real time with a line temperature measurement pattern instead of a point temperature measurement pattern. Additionally, a framework of distributed optical fiber data acquisition and remote transmission was proposed. Interconnection of multiple DTS hosts and remote transmission of temperature data were realized. Then, two-dimensional temperature fields of a typical dam block in different ages and longitudinal profiles of dam blocks with embedded fibers were reconstructed based on large amounts of temperature monitoring data and the Kriging difference algorithm. Temperature field reconstruction results showed that the temperature distribution law of the concrete arch dam was in accordance with the actual situation.

Jinping-I high arch dam is the highest arch dam (305 m) in the world, but the topography of its left and right sides of the arch is not symmetrical, which has a great impact on the overall stability of the arch dam. Based on the geomechanical model test and nonlinear numerical simulation, the evolution processes of cracks and failure during overloading in dam body and faults are demonstrated. Three safety factors of Jinping-I are gained and compared with other high arch dams. The safety factor of crack (K1) is 2.5, the factor of initial nonlinear deformation (K2) is 4.5 and the factor of the ultimate bearing capacity (K3) of Jinping-I is 7.5, indicating that the project has a high inherent safety. Treatments of foundation and weak zones are proved to be effective and then suggestions for reinforcement are given. Additionally, the relationships between model test and numerical simulation based on the deformation reinforcement theory are studied, which verifies that the unbalanced force is an effective indicator for cracking.

Determining vibration characteristics constitutes the first step in calibrating the finite element model in an old arch dam analysis. These characteristics provide the required information for a proper dynamic analysis of the coupled fluid-structure system used for risk assessment purposes. This paper investigates the detailed vibration characteristics of arch dams with heterogeneous material by applying random field theory. A group of six double-curvature arch dams are studied herein. The spatial material distribution using different correlation lengths is compared, and the response dispersion is quantified. An experimental meta-model design is developed for a specific class of dams, with an approximate analytical solution being derived. Ultimately, an iterative, random field-based system identification technique is proposed for old arch dams.

The internal damage of the model during the geomechanical model test is difficult to be detected. The failure and instability process of the arch dam are always accompanied by a large number of acoustic emission (AE) signals, which is related to the number of cracks in the model. AE technique was applied in the geomechanical model test of Mengdigou arch dam to analyze its failure process and overall stability. Noise filtering was conducted based on spectrum analysis of AE signal waveform . Parameter analysis was performed after noise filtering. The overall stability of the dam was evaluated by three characteristic overload safety factors: the crack initiation factor K 1 , nonlinear deformation factor K 2 and ultimate load factor K 3 , which were studied by AE parameter analysis. The failure process of Mengdigou arch dam was analyzed by the statistical analysis of AE hits and the wave velocity variation before and after test. AE analysis results were compared with the displacement and video monitoring results at the same time to verify the correctness of the evaluation method based on AE technique. The results showed that the failure process of the dam and foundation was well described by the AE technique, and the three safety factors of Mengdigou arch dam were defined more clearly. And as for Mengdigou arch dam, the fracture occurred at the dam heel area in the early stage of loading and the abutment of right bank was better than the left. The foundation damage was not serious after test and the overall instability was determined by instability of dam. Based on AE technique, the three overload safety factors was determined more clearly: K1 = 1.5–2.0, K2 = 4.5–5.0, and K3 = 11–11.5, which provided an important reference for the Mengdigou arch dam construction.

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.

This study investigates the local and global stability of the Luzzone Dam. Two finite element models were built, one with foundation rock, the other without. The purpose of this was to demonstrate a potential gulf between rigid connection modelling, and rock–structure interaction (RSI). Strand7 is not a traditional geotechnical finite element model (FEM) program, though performed well when modelling radial displacement on the Luzzone Dam. Generally, the percentage between a rigid base and RSI model displacement was 10%. This result was validated against previous numerical models on the structure. Static loads produced a radial displacement on the crown structure of 9.01 cm. Uneven stress distributions at the base of the structure were shown to be the most unpredictable result. With rigid base connections, these loads produced peak tensile stresses of 10.7 MPa. This was greater than its dynamic counterpart, asking questions about fully fixed restraints. It is noted that this is above yield and should be investigated further. Special attention will be devoted to determining the failure criteria in the simulated dams to suggest better practical guide lines for the practical engineers on site.

Dams are considered one of the most important vital installations in different eras due to the advantages they provide on the level of life for humans and other creatures or at the environmental level, in addition to being an important source for generating clean energy, which will reach the amount of its supply of electrical energy approximately 20% of the total energy in the world. With scientific progress, the era of globalization, and the emergence of structural types of dams, it has become important to study the structural composition of these types in addition to studying the extent of the impact of the dam’s shape on its stability. The arched dam is a solid concrete dam made arched at the upstream designed to withstand the hydrostatic pressure generated by water by its curved body. Depending on the type of construction arch dam can be classified into single and double curvature. The curved shape of the dam provides great performance and resistance to stresses generated from a variety of acting forces. The crack propagation under seismic loads of concrete arch dams with existing cracks on the dam's body has very limited studies. There are no clear studies links between the relation of crack propagation and the degree of curvature in arch dams. In this investigation, two different curvature models have been developed for the earthquake analysis of cracked concrete arch dams. The extended finite element method (XFEM) was used for nonlinear analyze the stability and propagation, development of cracks in concrete arch dams. A moderate earthquake magnitude of 5.7 M effects is considered in the (XFEM) analyses. The relation between the arch curvature and crack behavior are identified. The results obtained from this investigation indicate that increasing the degree of curvature of the arch dam will increase the dam stability under earthquake ground motion as well as providing good resistance for crack propagation and tensile stresses.

Dam deformation monitoring can directly identify the safe operation state of a dam in advance, which plays an important role in dam safety management. Three-dimensional (3D) terrestrial laser scanning technology is widely used in the field of deformation monitoring due to its fast, complete, and high-density 3D data acquisition capabilities. However, 3D point clouds are characterized by rough surfaces, discrete distributions, which affect the accuracy of deformation analysis of two states data. In addition, it is impossible to directly extract the correspondence points from an irregularly distributed point cloud to unify the coordinates of the two states’ data, and the correspondence lines and planes are often difficult to obtain in the natural environment. To solve the above problems, this paper studies a displacement change detection method for arch dams based on two-step point cloud registration and contour model comparison method. In the environment around a dam, the stable rock is used as the correspondence element to improve the registration accuracy, and a two-step registration method from rough to fine using the iterative closest point algorithm is present to describe the coordinate unification of the two states’ data without control network and target. Then, to analyze the displacement variation of an arch dam surface in two states and improve the accuracy of comparing the two surfaces without being affected by the roughness of the point cloud, the contour model fitting the point clouds is used to compare the change in distance between models. Finally, the method of this paper is applied to the Xiahuikeng Arch Dam, and the displacement changes of the entire dam in different periods are visualized by comparing with the existing methods. The results show that the displacement change in the middle area of the dam is generally greater than that of the two banks, increasing with the increase in elevation, which is consistent with the displacement change behavior of the arch dam during operation and can reach millimeter-level accuracy.