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Some high rockfill dams, built on deep overburden, utilize double concrete cutoff walls for seepage control, thereby introducing increased complexity to seepage characteristics in the dam foundation. This study focuses on a core rockfill dam located on the Dadu River in China, investigating the impact of dam body and foundation permeability coefficients on the percentages of hydraulic head reduction by the double cutoff walls. A multifactor sensitivity analysis, based on finite element method, is conducted to analyze this influence. Subsequently, an inversion model, integrating support vector regression and whale optimization algorithm, is proposed to identify parameters that align with seepage monitoring data. Results indicate that the permeability coefficients of the surface bedrock and the main grouting curtain exert the most significant influence. Parameters derived from the inversion model yield finite element calculations consistent with monitoring data. Moreover, upstream water level minimally affects the distribution of hydraulic head reduction percentages by the double cutoff walls. And the seepage gradient (G) in the dam foundation overburden remains below the permissible limit, with its relationship to the upstream water level (L) fitted as G=-1.03318+6.96E-4×L.This study may offer valuable insights for the construction and operational management of similar projects employing double cutoff walls.

To investigate the effects of strain rate and cyclic loading on the mechanical parameters of concrete compressive strength, residual strain, peak strain and elastic modulus, a series of cyclic loading tests over concrete were conducted by setting different numbers of cycles, magnitude factors, and cycle frequencies/periods based on the FST-1000 alpine geotechnical dynamic and static triaxial test system. The quantitative relationships between the mechanical parameters of concrete and the parameters of cyclic loading as well as the strain rate were also proposed. The results show that as the strain rate increases, the concrete compressive strength and elastic modulus increase linearly, while the residual strength and peak strain show a decreasing trend. Under cyclic loading, the compressive strength was quadratically related to each cyclic loading parameter, and the elastic modulus was quadratically related to the cyclic number and magnitude factor. The trend of the concrete compressive strength rate sensitivity undergoes a change at the specific thresholds of 0.145 for the magnitude factor and 1.93 Hz for the frequency. The minimum value of the peak strain rate sensitivity corresponds to the specific thresholds of 6023 for the number of cycles, 0.14 for the magnitude factor, and 1.38 Hz for the frequency thresholds, respectively. Additionally, the enhancement of the elastic modulus rate sensitivity occurs when the number of cycles exceeds 918 or when the magnitude factor surpasses 0.33. The results can provide a theoretical basis for the design of concrete structures and seismic engineering.

The geological complexity of the karst regions presents significant challenges, with the permeability coefficient being a critical parameter for accurately analyzing seepage behavior in hydraulic engineering projects. To overcome the limitations of traditional inversion methods, which often exhibit low computational efficiency, poor accuracy, and instability, this study utilizes a finite-element forward model and orthogonal experimental design to establish a sample set for permeability-coefficient inversion. A surrogate model for seepage calculation based on the Random Forest (RF) algorithm is subsequently developed. Furthermore, the Secretary Bird Optimization Algorithm (SBOA) is incorporated to propose an intelligent RF–SBOA inversion method for permeability-coefficient estimation, which is validated through a case study of the C-pumped storage power station. The results demonstrate that the RF model’s predictions for water levels at four boreholes closely align with the measured data, outperforming models such as CART, BP, and SVR. The SBOA effectively identifies the optimal geological permeability coefficient, with the borehole water-level inversion achieving a maximum relative error of only 0.128%, which meets the accuracy requirements for engineering applications. Additionally, the computed distribution of the natural seepage field is consistent with the typical distribution patterns observed in mountain seepage systems. During the normal water-storage phase, both the calculated seepage flow and gradient comply with engineering standards, while the seepage-field distribution aligns with empirical observations. This inversion model provides a rapid and accurate method for estimating the permeability coefficient of strata in the project area, with potential applicability to permeability inversion in other engineering geology contexts, thus demonstrating considerable practical value for engineering applications.

The seepage characteristics of clay core walls are crucial for the seepage safety of core rockfill dams, with the permeability coefficient in the unsaturated zone being nonlinear. To accurately determine the unsaturated seepage parameters in clay core rockfill dams, this paper first proposes an enhanced reptile search algorithm (ERSA) by applying three improvement strategies: Arnold’s cat chaotic map, nonlinear evolutionary factor, and adaptive Cauchy–Gaussian mutation with variable weight. Then, by integrating the ERSA with the unsaturated seepage finite element method, an inverse modeling approach is developed. This approach is applied to an actual rockfill dam with operational monitoring data to determine the unsaturated seepage parameters of the clay core. Results indicate that the ERSA outperforms the original RSA in test functions, and the calculation results of the seepage parameters determined through inversion are consistent with the monitoring data, showing an overall mean absolute error of 1.086 m. The inverse modeling approach provides a valuable reference for determining unsaturated seepage parameters in similar clay core rockfill dams.

The parameters’ inversion of saturated–unsaturated is important in ensuring the safety of earth dams; many scholars have conducted some research regarding the inversion of hydraulic conductivity based on seepage pressure monitoring data. The van Genuchten model is widely used in saturated–unsaturated seepage analysis, which considers the permeability connected to the water content of the soil and the soil’s shape parameters. A BP neural artificial network is a mature prediction technique based on enough data, and the marine predator algorithm is a new nature-inspired metaheuristic inspired by the movement of animals in the ocean. The BP neural artificial network and marine predator algorithm are applied in the permeability coefficient inversion of a core-rock dam in China; the results show that in the normal operation status, the BP network shows better accuracy, and the average of the absolute error and variance of the absolute error are both minimum values, which are 2.21 m and 1.43 m, respectively. While the water storage speed changes, the marine predator algorithm shows better accuracy; the objective function is calculated to be 0.253. So, the marine predator algorithm is able to accurately reverse the desired results in some situations. According to the actual condition, employing suitable methods for the inverse permeability coefficient of a dam can effectively ensure the safe operation of dams.

Deformation, as the most intuitive index, can reflect the operation status of hydraulic structures comprehensively, and reasonable analysis of deformation behavior has important guiding significance for structural long-term service. Currently, the health evaluation of dam deformation behavior has attracted widespread attention and extensive research from scholars due to its great importance. However, given that the sluice is a low-head hydraulic structure, the consequences of its failure are easily overlooked without sufficient attention. While the influencing factors of the sluice’s deformation are almost identical to those of a concrete dam, nonuniform deformation is the key issue in the sluice’s case because of the uneven property of the external load and soil foundation, and referencing the traditional deformation statistical model of a concrete dam cannot directly represent the nonuniform deformation behavior of a sluice. In this paper, we assume that the deformation at various positions of the sluice consist of both overall and individual effects, where overall effect values describe the deformation response trend of the sluice structure under external loads, and individual effect values represent the degree to which the deformation of a single point deviates from the overall deformation. Then, the random coefficient model of panel data is introduced into the analysis of sluice deformation to handle the unobservable overall and individual effects. Furthermore, the maximum entropy principle is applied, both to approximate the probability distribution function of individual effect extreme values and to determine the early warning indicators, completing the assessment and analysis of the nonuniform deformation state. Finally, taking a project as an example, we show that the method proposed can effectively identify the overall deformation trend of the sluice and the deviation degree of each measuring point from the overall deformation, which provides a novel approach for sluice deformation behavior research.

The accurate and efficient inversion of permeability coefficients is significant for the scientific assessment of seepage safety in concrete face rockfill dams. In addressing the optimization challenge of permeability coefficients with few samples, multiple parameters, and strong nonlinearity, this paper proposes a novel intelligent inversion method based on the Sobol-IDBO-SVR fusion surrogate model. Firstly, the Sobol sequence sampling method is introduced to extract high-quality combined samples of permeability coefficients, and the equivalent continuum seepage model is utilized for the forward simulation to obtain the theoretical hydraulic heads at the seepage monitoring points. Subsequently, the support vector regression surrogate model is used to establish the complex mapping relationship between the permeability coefficients and hydraulic heads, and the convergence performance of the dung beetle optimization algorithm is effectively enhanced by fusing multiple strategies. On this basis, we successfully achieve the precise inversion of permeability coefficients driven by multi-intelligence technologies. The engineering application results show that the permeability coefficients determined based on the inversion of the Sobol-IDBO-SVR model can reasonably reflect the seepage characteristics of the concrete face rockfill dam. The maximum relative error between the measured and the inversion values of the hydraulic heads at each monitoring point is only 0.63%, indicating that the inversion accuracy meets the engineering requirements. The method proposed in this study may also provide a beneficial reference for similar parameter inversion problems in engineering projects such as bridges, embankments, and pumping stations.

Seepage is the primary cause of dam failures. Conducting regular seepage analysis for dams can effectively prevent accidents from occurring. Accurate and rapid determination of seepage parameters is a prerequisite for seepage calculation in hydraulic engineering. The Whale Optimization Algorithm (WOA) was combined with Support Vector Regression (SVR) to invert the hydraulic conductivity. The good point set initialization method, a cosine-based nonlinear convergence factor, the Levy flight strategy, and the Quasi-oppositional learning strategy were employed to improve WOA. The effectiveness and practicality of Improved Whale Optimization Algorithm (IWOA) were evaluated via numerical experiments. As a case study, the seepage parameters of the Dono Dam located on the Baishui River in China were inversed, adopting the proposed inversion model. The calculated seepage field was reasonable, and the relative error between the simulated head and the measured value at each monitoring point was within 2%. This new inversion method is more feasible and accurate than the existing hydraulic conductivity estimation methods.

In this paper, the effects of different combinations of permeable spur dikes installed in the bend section of spillway on flow characteristics and energy dissipation rate were experimentally and numerically investigated. The results indicate that the permeable spur dikes installed in the spillway bend appreciably contributes to the improvement on the water surface uniformity, and the water surface uniformity can reach 90.13% with three permeable spur dikes installed in the bend. The permeable spur dike can lead to different degrees of decrease in the time-averaged longitudinal velocity in each zone of spillway bend. Different from previous study, no circulation zone is formed upstream and downstream of permeable spur dike due to the presence of permeable holes, and the flow upstream of permeable spur dikes could be divided into three distinctly different flow modes according to dye tracing. The presence of permeable spur dikes causes the concentration of TKE zone at concave bank of the spillway bend, except for TKE zone immediately next to the bottom plate. The TKE first increases and then decreases with the increase in the vertical distance from the bottom plate of the spillway bend, exhibiting a typical parabolic distribution. The energy dissipation rate in the spillway bend with permeable spur dike was calculated using a modified integral method, and the dissipation rate can reach as high as 21.08% with three spur dikes installed in the bend. HIGHLIGHTS Permeable spur dike was proven to be able to improve the flow characteristics in spillway.; Up to 20% energy dissipation rate can be achieved by using permeable spur dike in spillway.; The distribution of velocity in spillway with permeable spur dike was obviously decreased.; The arrangement of three permeable spur dikes has the best effect on improving the flow characteristics of spillway.;

To investigate the hydraulic fracturing in sulfate-attacked cement-based materials with tensile stress, splitting tensile strength test, hydraulic fracturing test under splitting load, and scanning electron microscopy test are conducted on cement mortar specimens immersed in Na2SO4 solution. The results reveal that the critical water pressure first increases and then decreases with the increase in immersion time, which is consistent with the tensile strength evolution. The tensile stress promotes the occurrence of hydraulic fracturing. Next, a critical water pressure model is proposed, in which the critical water pressure is expressed as a linear function of tensile strength and nominal tensile stress. Moreover, a theoretical formula is established to reveal the critical water pressure evolution mechanism of cement mortar exposed to sulfate attack. The evolution of critical water pressure depends on the porosity, matrix tensile strength, and expansion stress. Furthermore, a semi-empirical function is proposed to predict the critical water pressure evolution, which exhibits good accuracy. To avoid hydraulic fracturing, decreasing the porosity and tensile stress, increasing the matrix tensile strength, and releasing the expansion stress are effective strategies.

Analyzing the working conditions of a dam using safety monitoring indices (SMIs) is a relatively intuitive and effective method for dam safety evaluation. Therefore, a reasonable and accurate method for determining the SMIs of a dam is of vital importance for dam safety assessment. However, the current methods for determining the SMIs of dams, especially roller-compacted concrete (RCC) dams, have many shortcomings, such as ignoring the construction process of the dam, the coupling effect among multiple physical fields, etc. In this paper, a novel SMI determination method considering the seepage–stress coupling effects was proposed for RCC dams with the assistance of a constructed seepage and stress coupling model so as to address the deficiency of existing RCC dams in determining SMIs. The coupled mathematical model was developed in COMSOL Multiphysics to establish a finite element analysis model of an RCC gravity dam in Henan Province, China. Moreover, the seepage anisotropy of the RCC construction layers was also considered in the model. Finally, the seepage, stress, and deformation characteristics of the RCC dam were analyzed based on the model, and the seepage and deformation SMIs of the dam were determined and compared with traditional methods. The results show that seepage, stress, and displacement fields are distributed similarly for both coupled and uncoupled models. However, in contrast to the uncoupled model, the hydraulic head contour distribution is more dispersed in the coupled model. Additionally, the stress and displacement simulated by the coupled model increase at different rates, with a more pronounced stress concentration near the dam heel. Comparing the seepage and stress SMIs of RCC dam obtained from different methods, it was found that the indices of dam seepage discharge and crest displacement that are calculated by considering the seepage–stress coupling effect and anisotropic characteristics of RCC construction layers are 34.78% and 31.98% lower than results obtained by ignoring these two effects, respectively. Therefore, it is crucial to consider the seepage–stress coupling effect and the anisotropic characteristics of RCC when determining the SMIs for RCC dams.

Permeability characteristics in coarse-grained soil is pivotal for enhancing the understanding of its seepage behavior and effectively managing it, directly impacting the design, construction, and operational safety of embankment dams. Furthermore, these insights bridge diverse disciplines, including hydrogeology, civil engineering, and environmental science, broadening their application and relevance. In this novel research, we leverage a Convolutional Neural Network (CNN) model to achieve the accurate segmentation of coarse-grained soil CT images, surpassing traditional methods in precision and opening new avenues in soil granulometric analysis. The three-dimensional (3D) models reconstructed from the segmented images attest to the effectiveness of our CNN model, highlighting its potential for automation and precision in soil-particle analysis. Our study uncovers and validates new empirical formulae for the ideal particle size and the discount factor in coarse-grained soils. The robust linear correlation underlying these formulae deepens our understanding of soil granulometric characteristics and predicts their hydraulic behavior under varying gradients. This advancement holds immense value for soil-related engineering and hydraulic applications. Furthermore, our findings underscore the significant influence of granular composition, particularly the concentration of fine particles, on the tortuosity of water-flow paths and the discount factor. The practical implications extend to multiple fields, including water conservancy and geotechnical engineering. Altogether, our research represents a significant step in soil hydrodynamics research, where the CNN model’s application unveils key insights into soil granulometry and hydraulic conductivity, laying a strong foundation for future research and applications.

Ensuring the long-term, efficient, and safe operation of reservoir dams relies on the slope stability of embankment dams. Periodic fluctuations of the reservoir water level due to reservoir scheduling operations make the slope of the reservoir bank vulnerable to instability. To investigate the influence of various factors and their interactions with embankment dam slope stability under changing reservoir water levels, a global sensitivity analysis method is proposed that accounts for seepage–stress coupling. An embankment dam in Shaanxi Province, China, is studied as an example, with COMSOL Multiphysics software simulating the seepage and slope stability of the dam under fluctuating reservoir water level conditions and seepage–stress coupling. The global sensitivity analysis of factors affecting dam slope stability is accomplished by combining Plackett–Burman and Box–Behnken experimental designs, with ANOVA determining the sensitivity of each factor and interaction term. The results demonstrate that during the impoundment period of the reservoir, the saturation line is concave, and the overall stability safety of the dam slope increases first and then tends to be stable, according to the coefficient. The internal friction angle φ, cohesion c, and soil density ρs represent the three most sensitive factors affecting the stability and safety of the dam slope, while c × ρs is a second-order interaction term with significant sensitivity to the stability and safety coefficient of the dam slope. The reservoir drainage period infiltration line is convex, and dam slope stability first reduced and then increased. The magnitude of water level change H, internal friction angle φ, cohesion c, and soil density ρs are the four most sensitive factors for the coefficient of safety of dam slope stability, while c × ρs, H × ρs, and φ × ρs are the second-order interaction terms with significant sensitivity to the coefficient of safety of dam slope stability. These research findings and methods can offer valuable technical support and reference for the investigation and evaluation of the stability of embankment dam slopes.

Due to the characteristics of high heap and large volume, the complex layers of waste, high-water level of leachate, environmental pollution, and slope instability are easily produced. Although many researchers have studied landfill two-dimensional leachate migration law, three-dimensional seepage and stability of landfill sites have been rarely studied. This paper focuses on the heterogeneous characteristics of the landfill piles and analyzes the seepage field and slope stability of the landfill using statistical and numerical analysis methods. The calculated results are compared with the field measurement and literature research data to verify the reliability of the model, which may provide the basis for the design and safe and eco-friendly operation of the landfill. Taking an actual landfill as the research object, the saturated–unsaturated transient model of heterogeneous waste is applied to practical engineering. Considering the landfill process and heterogeneous permeability, the calculated maximum water level is higher. Compared with the homogeneous material, the difference in the water level of each waste layer is about 0.08∼1.88 m, which is not good for the stability of the landfill. Combined with the engineering characteristic distribution of a landfill, the heterogeneous stability model is applied to the actual project to study the influence of different unit weight and shear strength distribution on landfill stability. The established model is suitable for the study of two-dimensional and three-dimensional slope stability of landfill sites. Through the slope stability analysis of the three-dimensional landfill site, it is found that the bank slope of the reservoir is steep and prone to instability failure. In most studies, only the instability of the landfill is of concern, but the bank failure is ignored. In the process of landfill operation and management, while considering the capacity of the landfill, the stability of the bank slope should also be paid attention to, and if necessary, bank slope reinforcement or slope ratio improvement should be carried out.

Seepage is a main cause of dam failure, and its stability analysis is the focus of a dam’s design, construction, and management. Because a geological survey can only determine the range of a dam foundation’s hydraulic conductivity, hydraulic conductivity inversion is crucial in engineering. However, current inversion methods of dam hydraulic conductivity are either not accurate enough or too complex to be directly used in engineering. Therefore, this paper proposes a new method for the inversion of hydraulic conductivity with high application value in hydraulic engineering using an improved genetic algorithm coupled with an unsaturated equivalent continuum model (IGA–UECM). This method is implemented by a new code that fully considers engineering applicability. In addition to overcoming the premature convergence shortcomings of traditional genetic algorithms, it converges faster than Bayesian optimization and tree-structured Parzen estimator inversion algorithms. This method is verified by comparing the water head from drilling exploration and inversion. The results of the inversion are used to study the influence of a cement grouting curtain layout scheme on the seepage field of the Hami concrete-face rockfill dam in China, which is used as an engineering application case of the IGA–UECM. The law of the seepage field is reasonable, which verifies the validity of the IGA–UECM. The new inversion method of hydraulic conductivity and the proposed cement grouting curtain layout in this study offer possible strategies for the design, construction, and management of concrete-face rockfill dams.

To better understand the seepage field in tailings dam with a drainage structure that combines drainage mat, drainage tube, and geotextile, an equivalent seepage analysis method for the drainage structure is presented. In the method, an equivalent drainage structure is suggested to replace the original drainage. It has enough size to be easily presented in the three-dimensional (3d) model of a tailings dam. According to a back analysis procedure using the quasi-3d models of a tailings dam with original and equivalent drainage structures, the material properties of the equivalent drainage structure can be obtained under the principle of drainage capacity equivalence. It is demonstrated that the suggested method is accurate enough to capture the seepage field in a tailings dam based on comparing the calculated and measured phreatic lines in a tailings dam for verification. Then, the method is employed to investigate the seepage field in a tailings dam in China for a case study. The rise of water level, damage of drainage structure, or increase of tailings discharge speed and time will lift up phreatic line. After terminating tailings discharge, phreatic line will first rise and then fall. The effect of tailings discharge on phreatic line will almost disappear after terminating tailings discharge for 24 h.

Particle shape is one of the critical parameter factors that affect gravel’s pore structure and permeability. However, few studies have considered its effects on engineering applications due to the difficulty of conducting laboratory tests. To overcome these difficulties, new methods of estimating the gravel pack shape that involve manual work and measuring the surface area of particles and pores based on support vector machine segmentation and the reconstruction of X-ray diffraction computed tomography (CT) images were proposed. Under the same conditions, CT tests were carried out on gravel packs and two other regular-shaped particle packs to investigate the influence of particle shape on the fractal dimension of gravel’s pore–particle interface and the specific surface area of the pore network. Additionally, permeability tests were performed to study the effect of particle shape on gravel’s hydraulic conductivity. The results showed that a gravel pack with a larger aspect ratio and a smaller roundness had a larger specific pore network surface area and a more complex pore structure, leading to lower permeability. This kind of gravel had a more significant length, quantity, and tortuosity of the seepage path when seepage occurred in a two-dimensional seepage field simulation. Therefore, we suggest that the filter materials of hydraulic projects should preferably use blasting gravel with a larger aspect ratio and smaller roundness to achieve better anti-seepage properties. In addition, projects can increase pores’ specific surface area using our method as a control factor in filter construction.

The seepage parameters of the dam body and dam foundation are difficult to determine accurately and quickly. Based on the inverse analysis, a Gray Wolf Optimizer (GWO) was introduced into this study to search the target hydraulic conductivity. A novel approach for initialization, a polynomial-based nonlinear convergence factor, and weighting factors based on Euclidean norms and hierarchy were applied to improve GWO. The practicability and effectiveness of Improved Gray Wolf Optimizer (IGWO) were evaluated by numerical experiments. Taking Kakiwa dam located on the Muli River of China as a case, an inversion analysis for seepage parameters was accomplished by adopting the proposed optimization algorithm. The simulated hydraulic heads and seepage volume agree with measurements obtained from piezometers and measuring weir. The steady seepage field of the dam was analyzed. The results indicate the feasibility of IGWO in determining the seepage parameters of Kakiwa dam.

Pumped storage power station (PSPS) is an important clean energy project that plays an important role in ensuring the economical, safe, and stable operation of power systems and alleviating the contradiction of peak load regulation. Deformation analysis of the built and under construction PSPS dam was an important process of dam design and operation, which was of great significance to ensure the safe operation of hydraulic structures in the reservoir site. Nevertheless, there were many parameters involved in the model for analyzing dam deformation, which brings a large workload to the inversion and application of model parameters. In this study, the asphalt concrete face rockfill dam (ACFRD) of a PSPS in Ningxia, China, was taken as an example, a dam deformation 3D finite element analysis model based on the Duncan–Chang E-B model was constructed, and the orthogonal test method was used. The model parameters of the main rockfill zone, secondary rockfill zone, and reservoir bottom backfill zone were taken as factors for the sensitivity analysis of horizontal displacement of dam H, vertical displacement u, and asphalt concrete face tensile strain ε. The results showed that initial bulk modulus base Kb, damage ratio Rf, and initial elastic modulus base K had a relatively higher sensitivity and had significant impacts on the calculation results, while internal friction angle φ, fraction angle reduction φ, bulk modulus index m, and elastic modulus index n had a relatively lower sensitivity, which had no significant impact on the calculation results. Therefore, when using the Duncan–Chang E-B model to analyze the deformations of a PSPS dam and asphalt concrete face, Kb, Rf, and K should be the focus. Parameters with a low sensitivity could be determined by engineering analogy so as to achieve the purpose of improving calculation efficiency under the premise of ensuring calculation accuracy. Meanwhile, these parameters should also be strictly controlled during construction. The results of this study could provide a reference for the design and safety assessment of ACFRD in PSPS.

To address the problem of dissolution damage during the long-term service of concrete hydraulic buildings, the concrete dissolution damage degree D and contact dissolution loss model with time were proposed by combining the results of indoor concrete dissolution tests. A mathematical model of the evolution of concrete parameters with time was developed. In the context of an underground concrete culvert project, a numerical analysis model of concrete dissolution deterioration was established, according to which the effects of different damage locations on the stress and displacement of concrete culverts were analyzed. The results show that the settlement value of the surface and the soil pore pressure value increase more when the bottom of the culvert is damaged by dissolution, and the settlement of the surface from the bottom damage is about 1.07~1.16 times of that from the top damage. When the damage position deviates from the center line of the culvert, the maximum point of vertical displacement in the transverse settlement trough of the ground surface deviates from the centerline of the culvert by about 3~5 m in the horizontal direction. At the bottom of the culvert, the concrete permeability coefficient reaches 6.957 × 10−8 m/s~8.354 × 10−8 m/s in about 13~16 years after the occurrence of dissolution damage, and local leakage occurs, causing a significant increase in the pore pressure of the soil near the leakage location. The overall settlement and uneven settlement resulting from the dual action of dissolution deterioration of concrete and infiltration pressure can have a serious impact on the upper channel buildings.

Along with the increased use of water resources, some large water conservancy projects began construction to address power supply shortages and control flooding and drainage. As investment grows, construction cycles lengthen, external environmental impacts become bigger, and civil engineering project management becomes more complex. The real aim of the hydraulic-structure engineering project model is to manage ways of delivering the project on time while maintaining reasonable quality standards and building costs, to optimize project value. We note that the trade-off between conflicting objectives in a water conservancy project in an uncertain environment is a difficult task. To simulate the relationship between a project’s construction quality and its time limit, two new piecewise functions—a double exponential function and a quadratic function—were proposed, and then a fuzzy multi-mode discrete time–cost–quality trade-off concept for water-management projects was established. This model finds the best solution to an NP-hard problem using the particle-swarm optimization algorithm (PSO). A comparison of the calculations to previous studies validates the model and its computational approach. The optimized results of a water conservation project are provided as a conceptual framework for project planning and construction timeframes.

The deep-water temperature of large reservoirs is low, thus easily leads to the appearance and expansion of cracks on the upstream faces of concrete dams. Therefore, in the design phase of a dam, accurately predicting the water temperature distribution at the front of the dam during the operation period of the reservoir takes on a critical significance in the dam simulation analysis of temperature control and crack prevention design. The vertical one-dimensional numerical algorithm of reservoir water temperature was optimized in accordance with the heat transfer equation and considering certain factors (e.g., water temperature transfer, inflow distribution, slag at the bottom of the reservoir, and solar radiation) to solve the above problem. The Nash–Sutcliffe efficiency coefficient (NSE) was adopted to analyze the simulation error qualitatively and quantitatively, and to verify the applicability of the algorithm. The results validated with temperature data measured in four reservoirs illustrate that the proposed algorithm exhibits a higher prediction accuracy than the empirical equation method for water temperature at the front of dams at different scales under different operation modes. The mean deviations of the proposed algorithm are all below 1 °C, and the Nash–Sutcliffe efficiency coefficients (NSE) are all above 0.85. Moreover, compared with the three-dimensional numerical algorithm, the proposed algorithm not only requires a smaller amount of data, but also is simpler to apply and has a higher efficiency. The twelve-month water temperature calculation for a large reservoir takes less than 1 min. This study further reveals that the slag at the bottom of the reservoir is capable of significantly rising the temperature at the dam heel by 5–6 °C. The program compiled by the proposed algorithm can be seamlessly embedded in the simulation program for concrete dam temperature control; thus, the reliability of the simulation of the temperature can be enhanced for temperature field and stress field on the upstream surface of the dam without affecting the total calculation efficiency.

Clay core dams are widely applied in reservoir construction, regulating water resource and provide electric power. Leakage is a common problem in reservoir construction, and the leakage amount, which not only affects the economic benefits of the project, but also relates to the safety of the dam body, is difficult to estimate. According to Darcy’s law and stable seepage theory, an analytical method can be proposed to calculate the leakage of the clay core dam to gain the seepage flux in a short time. By making some reasonable assumptions, we propose formulae for seepage calculation in different conditions of the position of the groundwater levels, below or above the reservoir bottom. Both sets of formulae contain two parts of leakage calculation, i.e., leakage from the reservoir bottom and leakage from the dam body. By using the proposed analytical method, the leakage of clay core dams can be estimated considering the influence of the groundwater level. To prove the rationality of the analytical method, a simple numerical model can be established using Geo-studio 2020 to calculate the seepage flux of the clay core dam, where relative errors between numerical solutions and analytical solutions are less than 10%. To verify the feasibility in engineering applications, the proposed method was applied to calculate the seepage of a clay core dam in Sichuan, China, which was also calculated using numerical methods by establishing a three-dimensional model. The results show the rationality of the analytical method, which can strike a balance between precision and efficiency.

The deterioration of mortar has an adverse impact on the deformation and stress state of the masonry arch dam, after freeze-thaw cycles, in long-term operation. The purpose of this paper is to investigate the effect of reinforcement grouting on the stress of a thin masonry arch dam and propose a reasonable grouting method in the case of mortar deterioration. The determination of the ultimate grouting pressure is another main focus. The masonry material was generalized by combining a linear elastic model and the proportional weighted average under the condition of deterioration caused by freeze-thaw cycles. A series of analytical methods were proposed for the research of grouting effect on dam stress, based on which the ultimate grouting pressure is calculated in various cases. Results demonstrate that the dam tensile stress may exceed the allowable value in the following operation. Then, some recommended methods for the grouting layout and the estimation of grouting pressure were put forward by integrating the grouting field test with numerical analysis for reinforcement. The research conclusions might have a guiding significance for the reinforcement of similar projects.

With massive energy demands, the majority of developing countries are at a critical juncture in their industrial development. Their energy structure, on the other hand, is relatively specific and heavily reliant on fossil fuels, resulting in significant environmental pollution. As a result, the development of clean energy is on the horizon, which is related not only to whether developing countries can build a resource-saving and environmentally friendly society but also to whether they can achieve socially sustainable development. As a significant clean energy source, not only does hydropower play an important role in the development of an energy-efficient and environmentally friendly green economy, but it also has numerous benefits such as shipping, irrigation, flood control, and water supply. So, hydropower development is critical for developing countries to adjust their energy structures, achieve regional development balance, and ensure river defense safety. However, precision guidance technology is maturing around the world. If one side’s water-retaining dam is accurately blasted in the event of a full-scale war or local conflict, it may cause significant economic and human losses. Dam safety and protection from strong explosions deserve special attention given the obvious seriousness of the consequences. It is critical to improve the anti-explosion safety of major hydraulic structures by revealing the dynamic response behavior, damage mechanism, and dam characteristics under explosion impact loads, as well as evaluating the dam’s condition after extreme loads. In the critical work of disaster prevention and mitigation, this is crucial to our social and economic development. This study is not only a key technical problem and an important strategic task in hydraulic structure construction, but it may also serve as a guideline for governments to take effective measures to reduce the loss of dam break under special circumstances.

There exist shear and seepage behaviors on the interface between clay core and concrete slab in clay core dams. In order to investigate the seepage characteristics of the clay–structure interface after shear deformation, a shear-seepage test system is proposed, in which the seepage direction is perpendicular to the shear direction. The shear test and shear-seepage test are performed on clay–metal and clay–mortar interfaces under different normal stresses (100, 200, 400, 800, and 1600 kPa). The shear stress-deformation curves of two clay–structure interfaces exhibit softening behavior and residual friction behavior. The interface roughness can enhance peak and residual shear strength and increase peak displacement. The shear-seepage test results show that specimen permeability decreases first and then increases to a stable value as shear deformation increases under low normal stress, while it decreases continuously and then retains stability under high normal stress. The interface roughness enhances specimen permeability under low normal stress, whereas it has a weak effect on specimen permeability under high normal stress. Compared with initial permeability, shear deformation reduces specimen permeability rather than raise it. The ratio of stabilized permeability coefficient to initial value ranges from 0.6 to 0.8. The clay–structure interface still has a good resistance to seepage failure after shear deformation. The shear dilation features and interface pore decrease caused by shear behavior are the internal attributions of clay–structure specimen permeability evolution.

The calcium leaching effect leads to a decrease in the impermeability of the impervious curtain. The inverse analysis strategy was introduced in this study because the calcium leaching parameters of the curtain are not easy to determine. An orthogonal design and the finite element method were used in the strategy. The time-series data of hydraulic head and leakage volume were applied to construct the objective function. The extreme learning machine (ELM) was proposed to build the reflection sets. Genetic algorithm (GA), simulated annealing (SA), sparrow search algorithm (SSA), and particle swarm optimization (PSO) were employed to accelerate the iterative search for the target parameters. The target parameters of the calcium leaching model were used for finite element verification by comparing the monitored and simulated values. The simulated values of hydraulic head and leakage by PSO show good agreement with measurements. The evolution of the curtain permeability coefficient in 100 years was analyzed. The results demonstrate the strategy’s feasibility in determining the curtain’s calcium leaching parameters and permeability coefficients.

Hydraulic fracturing may be induced easily in a cement-based structure in a sulfate-rich environment, which threatens engineering safety. In order to investigate the evolution of critical water pressure, a series of hydraulic fracturing tests and splitting tensile strength tests on the cement mortar under different sulfate-exposure periods are performed. The critical water pressure of the cement mortar under sulfate attack experiences an initial increase stage and a subsequent decrease stage. A stress intensity factor is modified by two proposed damage variables which are crack length and fracture stress. Then, the relationship between the critical water pressure and the tensile strength is established. Moreover, an evolution model of the critical water pressure is proposed, which reveals that the matrix tensile strength and porosity of cement mortar strongly affect the critical water pressure evolution. Additionally, an empirical formula is suggested to describe the critical water pressure evolution of the cement mortar under sulfate attack, and its validity is verified by experimental results.

The calcium leaching effect inevitably increases the grout curtain hydraulic conductivity. It is diffucult to sample and obtain the leaching-related calculation parameters for deep-buried grout curtains. This study introduced the inversion method into the calcium leaching analysis to get proper leaching-related calculation parameters and accurate results. An inverse analysis model was proposed using the genetic algorithm (GA) and finite element analysis technology to solve the calcium leaching problems. The objective function is constructed using the hydraulic head and leakage quantity time-series measurements, which improves the uniqueness and reliability of the inverse results. The proposed method was applied to the inverse analysis of the hydraulic conductivity evolution of the grout curtain in a concrete dam foundation. The predicted water heads and leakage quantity are consistent with the monitored data, indicating the rationality of this simulation. The grout curtain hydraulic conductivity prediction in 100 years is also presented. The results illustrate the feasibility of the proposed method for determining leaching-related parameters and the hydraulic conductivity prediction in the leaching process.

Seepage flux is very important in many hydraulic projects such as in the upper reservoir of a pumped storage power station because of its effect on economic benefits. However, upper reservoirs with a relatively high altitude are generally located above the groundwater level; thus, their leakage is difficult to estimate accurately. Here, using steady seepage theory and Darcy’s law, we propose a simplified calculation method to estimate the leakage of slope-wall rock-fill dams with a horizontal blanket. Using a one-dimensional governing equation for unsaturated seepage flows with the assumption of porous continuous media, formulas are derived for calculating the seepage flux of the dam in a steady state with different groundwater levels, which are mainly divided into two situations: those that are lower or higher than the bottom of the horizontal blanket. Then, two engineering examples are developed to assess the proposed method; the relative errors between the analytical results and numerical results are less than 10%. The results obtained from other analytical methods introduced by other researchers are also compared with our numerical results. The comparison results show that the proposed method is reliable and can be used for the estimation of reservoir leakage in situations where rapid results are needed, such as benefit assessments and safety evaluations.

This paper presents a new seepage inversion technique to predict the permeability coefficient of the rock mass with developed fracture or fault. With the measured data of flow and water head of boreholes, the permeability coefficient of the rock masses near the boreholes are obtained by inverse calculation on the basis of unsteady seepage tests. Then, a flexible tolerance method is proposed to invert the permeability coefficient of rock masses in different zones of the reservoir area. This comprehensive inversion analysis method is applied in one actual project of the water supply reservoir. The equivalent permeability coefficient of the rock masses in the range of 0 m to 16.0 m below the road surface near the dam axis on the left bank of the mountain is 1.12 × 10−3 cm/s. The root mean squared error and coefficient of determination of the measured and calculated values are 1.33 × 10−4 m3/s and 0.9976 m3/s, respectively. The rock masses in the reservoir site area have high permeability. The groundwater level in the junction area and the mountains on both sides of Shangmo reservoir is low, and the hydraulic gradient is small. The maximum error between the calculated value of the groundwater level and the measured values is −0.41 m, and the relative error is −4.36%. The recommended anti-seepage scheme can effectively solve the problem of large leakage in the reservoir area. The results show that the innovative approach is appropriate for the seepage analysis of the field with the fractured rock masses and more meaningful from an engineering point of view.

Effective methods for extending the storage capacity of tailings for a mining company include expanding and increasing the height of the tailings dam. However, this change could lead to an uplift in the phreatic line and a decrease in the slope stability. In this paper, a new drainage system combining a horizontal drainage pipe with an upward bending slotted pipe was proposed and applied to the design of a seepage-proof system for the Xigou tailings dam with an increased height. To accurately simulate the performance of the seepage control system, a three-dimensional finite element model was established on the basis of a geological investigation of the site conditions. In this work, a substructure technique was used to model the drainage pipe with a small radius and dense spacing to reduce the difficulty in mesh generation, and a back-analysis method called MPSO-BP (modified particle swarm optimization algorithm and a back propagation neural network) was used to correct the measured permeability coefficients. The results show that the new drainage system can effectively dissipate the seepage pressure, decrease the phreatic surface, and improve the safety factors of the slope stability. The proposed drainage system can also meet the seepage stability requirements of the higher tailings dam. Additionally, this system can be widely deployed in similar projects.

High-pressure hydraulic fractures are often reported in real engineering applications, which occur due to the existence of discontinuities such as cracks, faults, or shear bands. In this paper, a hybrid finite volume and extended finite element method (FVM-XFEM) is developed for simulating hydro-fracture propagation in quasi-brittle materials, in which the coupling between fluids and deformation is considered. Flow within the fracture is modelled using lubrication theory for a one-dimensional laminar flow that obeys the cubic law. The solid deformation is governed by the linear momentum balance equation under quasi-static conditions. The cohesive crack model is used to analyze the non-linear fracture process zone ahead of the crack tip. The discretization of the pressure field is implemented by employing the FVM, while the discretization of the displacement field is accomplished through the use of the XFEM. The final governing equations of a fully coupled hydro-mechanical problem is solved using the Picard iteration method. Finally, the validity of the proposed method is demonstrated through three examples. Moreover, the fluid pressure distribution along the fracture, the fracture mouth width, and the pattern of the fracture are investigated. It is shown that the numerical results correlated well with the theoretical solutions and experimental results.

Mathematical physics equations are often utilized to describe physical phenomena in various fields of science and engineering. One such equation is the Fourier equation, which is a commonly used and effective method for evaluating the effectiveness of temperature control measures for mass concrete. One important measure for temperature control in mass concrete is the use of cooling water pipes. However, the mismatch of grids between large-scale concrete models and small-scale cooling pipe models can result in a significant waste of calculation time when using the finite element method. Moreover, the temperature of the water in the cooling pipe needs to be iteratively calculated during the thermal transfer process. The substructure method can effectively solve this problem, and it has been validated by scholars. The Abaqus/Python secondary development technology provides engineers with enough flexibility to combine the substructure method with an iteration algorithm, which enables the creation of a parametric modeling calculation for cooling water pipes. This paper proposes such a method, which involves iterating the water pipe boundary and establishing the water pipe unit substructure to numerically simulate the concrete temperature field that contains a cooling water pipe. To verify the feasibility and accuracy of the proposed method, two classic numerical examples were analyzed. The results showed that this method has good applicability in cooling pipe calculations. When the value of the iteration parameter a is 0.4, the boundary temperature of the cooling water pipes can meet the accuracy requirements after 4~5 iterations, effectively improving the computational efficiency. Overall, this approach provides a useful tool for engineers to analyze the temperature control measures accurately and efficiently for mass concrete, such as cooling water pipes, using Abaqus/Python secondary development. [ABSTRACT FROM AUTHOR]