Search Results (143)

The service behavior of polyurea used for joint sealing and seepage control in concrete arch dams is governed by complex material, geometric, and interfacial nonlinearities. This study developed a generalized interface element model incorporating damage evolution based on the nonlinear Ogden constitutive theory of polyurea materials. Using the Xiaowan Arch Dam as the engineering case, a multiple-nonlinearity coupled numerical model was established, covering the construction period, impoundment period, and temperature cycles during the operation period. The mechanical responses of surface polyurea at different locations and under varying material parameters were systematically investigated. Results show that the proposed coupled model accurately captures nonlinear contact behavior. Governed by the structural stress pattern of the arch dam, the impermeable coating is predominantly subjected to compression, while regions of high tensile stress are confined to the bottom joint areas. In seepage-control design, the coating’s restraining effect on macroscopic dam deformation can be neglected; however, dam deformation must be treated as the primary boundary condition. It is recommended that polyurea with an elastic modulus of 50 MPa and a 3 mm thickness be adopted. Blindly increasing coating thickness or stiffness may instead significantly elevate the risk of internal tensile stress. Full article

River sand is an essential resource for the construction industry and is extensively used worldwide. However, its limited availability has led to supply shortages and rising costs. As a non-renewable resource, sand accumulates behind river dams, and its extraction using mechanical dredgers harms river ecosystems. Overexploitation has depleted riverbeds and caused significant environmental concerns. The construction sector faces challenges such as water and sand scarcity, along with the use of substandard sand. Growing awareness of the environmental damage caused by excessive sand use has prompted researchers to explore alternatives to sand in cement and concrete. One promising approach is sand-free plastering, which is being investigated as a sustainable alternative to traditional sand-based plaster. We analyzed the physical properties of sand-free plaster materials and the development of an automated robotic system for applying these materials in green buildings. By promoting sustainability, these innovations aim to address the challenges posed by sand scarcity while minimizing environmental impacts. Full article

The safety of waterproof joints in concrete-faced rockfill dams (CFRDs) founded on deep overburden was determined during construction, impoundment, and sedimentation periods, employing the flexible FEM-NSBPFEM coupled method. Through eleven numerical scenarios, critical deformation zones are identified, and the effects of upper soil loads (upstream weighting and sedimentation) and cutoff wall design plans on the key joint between the connecting plate and the cutoff wall (J1) are systematically evaluated. The principal findings reveal that: (1) Joint deformation is dominated by vertical shear, primarily localized at J1, with the shear deformation at J1 reaching approximately 15 cm when the height of the upper soil load reaches 40 m. (2) Upper soil loads exert a greater influence on J1 shear deformation than hydrostatic pressure. (3) Increasing sedimentation loads cause J1 shear deformation to initially mirror impoundment trends before undergoing a sharp surge, and the effect is exacerbated by higher upstream weighting loads. (4) Shear deformation varies markedly between closed and suspended cutoff walls, whereas variations among different suspended wall designs are smaller. Based on these mechanical insights, two optimization schemes for the impermeable system are proposed, effectively constraining joint shear and opening displacements to within 4 cm. These findings provide critical guidance for the reliability analysis and design optimization of CFRD impermeable systems in deep overburden environments. Full article

The layer-by-layer construction process of roller-compacted concrete (RCC) leads to the formation of layer zones, resulting in the transversely isotropic constitutive behavior of the RCC dam. Crucially, the thickness of the layer zone exerts a non-negligible influence on the overall deformation behavior of the RCC dam structure. An analytical expression for the thickness of the layer zone is derived based on the equivalent elastic modulus theory, and the influence of concrete with the same and different properties on the thickness of the layer zone is investigated. Numerical analysis is employed in conjunction with the RCC dam project to quantitatively assess the influence of layer thickness on the displacement of the dam structure. The numerical results demonstrate that considering the thickness of the layer zone leads to a substantial increase in both horizontal and vertical displacements of the dam. Furthermore, the range of extreme values of layer thickness is established using the variational principle of elasticity mechanics. When the elastic modulus ratio of RCC with layer zones to bulk concrete β is 0.85–0.99, a reasonable thickness of the layer can be obtained. When the weakening coefficient k and β are close to 1, the thickness of the layer is close to 10 cm, which is close in nature to the RCC dam. Full article

In large-scale dam construction, the efficiency of concrete transport operations is fundamentally governed by the coordination between horizontal hauling and vertical hoisting capacities. Traditional experience-based scheduling approaches often fail to capture the stochastic, cyclic, and resource-coupled nature of these transport systems. This study developed a closed queuing network-based stochastic simulation framework to model dam concrete transportation as a finite-population cyclic service system. The process was abstracted into sequential service stages with stochastic service times, and a structured state-space representation combined with time-step simulation was constructed to describe dynamic resource occupation and task transitions under varying truck and cable crane configurations. Application to a real large-scale dam project revealed a characteristic multi-stage performance evolution pattern governed by capacity matching mechanisms. As the truck fleet size increased, system performance transitioned from a transport-limited regime to a capacity-coordination regime and ultimately to a hoisting-saturated regime in which further fleet expansion yielded diminishing returns. Sensitivity analysis demonstrated that hoisting capacity imposed an upper bound on system throughput, while adaptive fleet reconfiguration could restore operational equilibrium under constrained equipment availability. The results indicated that dam concrete transport should be treated as a dynamic capacity regulation problem rather than a static allocation task. The proposed framework provides an interpretable and quantitative decision-support tool for equipment configuration, bottleneck identification, and adaptive scheduling in large-scale hydraulic infrastructure projects. Full article

Seepage through construction joints is a major factor affecting uplift pressure and long-term safety of concrete dams. Pre-existing joints with millimeter-scale openings provide preferential flow paths, where hydraulic pressure can induce joint opening and permeability escalation. In this study, seepage-induced joint-opening behavior is investigated using a coupled hydromechanical numerical framework with damage-dependent aperture evolution. The impacts of initial crack width, interface cohesiveness, and interface tensile strength on the evolution of crack opening displacement (COD) and hydraulic instability are comprehensively isolated by parametric studies. The results show that, once tensile opening is activated, variations in cohesion have a negligible influence on pressure–COD responses and failure pressure, indicating that cohesion degradation does not control seepage-induced instability in pre-existing cracks. In divergence, interface tensile strength strongly governs damage initiation, the onset of rapid crack opening, and the critical hydraulic pressure at failure. Larger initial crack widths act as geometric accelerators, leading to earlier instability and enhanced permeability evolution under increasing seepage pressure. A dimensionless, pressure–tensile strength ratio is shown to unify the observed responses, revealing a transition from a geometry-controlled regime to a damage-dominated failure regime. These findings indicate that seepage-induced instability in concrete dams is primarily controlled by tensile resistance of construction joints rather than cohesion degradation, providing guidance for uplift pressure assessment and seepage control design. Full article

Concrete arch dams, which account for about 4% of large dams worldwide, are distinguished by their efficient geometry, economy, effective load distribution, and high storage capacity. Under thermal loads, they are susceptible to unusual behavior in terms of deflection and stresses due to geometrical peculiarities, construction methodology, and restraints, which in turn may cause potential failure. This paper analyzes the behavior of a 50-year-old double-curvature, high, thin concrete arch dam under extreme thermal loading and fluctuating water levels, using 3D linear elastic FEM analyses and monitoring data. It rigorously evaluates structural response—deflections and stresses—at salient locations and interaction zones under large temperature fluctuations, a key yet underexplored risk for thin concrete arch dams in tropical and equatorial regions. Using real monitoring data, the research also examines the effectiveness of rehabilitation measures designed to mitigate thermal impacts. Results indicate that the dam deflection reverses at extreme temperature drops and rises when the reservoir is at higher or lower levels, respectively, which is not unusual for thin concrete double-curvature arch dams. Long-term exposure to high extreme temperatures with low reservoir water levels may become a concern, as it can cause higher tensile stresses at salient points and significant dam deflections towards upstream. Full article

The anti-seepage performance of concrete directly affects the anti-seepage effect and durability of the concrete face slab of the rockfill dam. Since the panel concrete is often in a complex stress state in practical engineering, its permeability coefficient will be significantly affected by the stress state. In this paper, the fixture is designed to apply different levels of axial compression and axial tensile load to concrete specimens, and the air-void structure, water absorption, and permeability coefficient are measured under sustained load. The results show that with the increase in axial compressive load, the air-void spacing, capillary water absorption and permeability coefficient decrease first and then increase, and the critical stress threshold is 0.38 f_c. For the specimen with a water-cement ratio of 0.35, the permeability coefficient decreases by 45.1% and then increases by 802.4%. However, when the axial compressive load exceeds a certain threshold, the internal structure is damaged, and the permeability increases again. With the increase in axial tensile load, the air-void spacing, capillary water absorption, and permeability coefficient continue to increase, indicating that axial tensile stress will aggravate the expansion of micro-cracks in concrete and significantly increase the permeability coefficient. For the specimen with a water-cement ratio of 0.35, the permeability coefficient increases by 197.9% and then increases by 734.3% with the increase in tensile stress. The concrete with a water-cement ratio of 0.5 is more sensitive to the change in stress state than 0.35, showing a greater change in permeability coefficient and capillary water absorption. The research can provide an important basis for the design and construction of concrete face rockfill dam panel. Full article

Rapid urbanization has led to increasing structural modification of river catchments through dam construction and concrete-lining of natural channels as flood management measures. These interventions can alter the natural hydrology. This necessitates assessment of their influence on hydrology at a catchment scale. However, such evaluations are particularly challenging in data-scarce regions such as the Chongwe River Catchment, where hydrometric records capturing conditions before and after structural modifications are limited. Therefore, we applied a 2D rain-on-grid approach in HEC-RAS to evaluate changes in high-flow responses to short-duration, high-intensity rainfall events in the Chongwe River Catchment in Zambia, where structural interventions have been implemented. The terrain was modified in HEC-RAS to represent 21 km of concrete drains and ten dams. Sensitivity analysis conducted on five key model parameters showed that parameters controlling surface runoff generation, particularly curve number, exerted the strongest influence on simulated peak flows, while routing-related parameters had a secondary effect. Model calibration and validation showed strong performance with R² = 0.99, NSE = 0.75 and PBIAS = −0.68% during calibration and R² = 0.95, NSE = 0.75, PBIAS = −2.49% during validation. Four scenarios were simulated to determine the hydrological effects of channel concrete-lining and dams. The results showed that concrete-lining of natural channels in the urban area increased high flows at the main outlet by approximately 4.6%, generated localized instantaneous maximum channel velocities of up to 20 m/s, increased flood depths by up to 11%, decreased lag times and expanded flood inundation widths by up to 15%. The existing dams reduced peak flows by about 28%, increased lag times, reduced flood depths by about 11%, and reduced flood inundation widths by up to 8% across the catchment. The findings demonstrate that enhancing stormwater conveyance through concrete-lining must be complemented by storage to manage high flows, while future work should explore nature-based solutions to reduce channel velocities and improve sustainable flood mitigation. Therefore, the study provides event-scale insights to support flood-risk management and infrastructure planning in rapidly urbanizing, data-scarce catchments. Full article

Concrete arch dams represent a predominant dam type in water conservancy and hydropower projects in China. The control of concrete placement progress during construction directly impacts project quality and construction efficiency. Traditional manual monitoring methods, characterized by delayed response and strong subjectivity, struggle to meet the demands of modern intelligent construction management. This study introduces machine vision technology to monitor the concrete placement process and establishes an intelligent analysis system for construction scenes based on deep learning. By comparing the performance of U-Net and DeepLabV3+ semantic segmentation models in complex construction environments, the U-Net model, achieving an IoU of 89%, was selected to identify vibrated and non-vibrated concrete areas, thereby optimizing the concrete image segmentation algorithm. A comprehensive real-time analysis method for placement progress was developed, enabling automatic ternary classification and progress calculation for key construction stages, including concrete unloading, spreading, and vibration. In a continuous placement case study of Monolith No. 3 at a project site, the model’s segmentation results showed only an 8.2% error compared with manual annotations, confirming the method’s real-time capability and reliability. The research outcomes provide robust data support for intelligent construction management and hold significant practical value for enhancing the quality and efficiency of hydraulic engineering construction. Full article

The Hisayamada Dam (22.5 m high, 75.4 m long), constructed in 1924 as a water supply facility, is a masonry arch–gravity concrete dam with a slender arch shape. Although it was the first theoretically designed arch-type dam in Japan, seismic forces were not considered at the time of construction. This study evaluates its seismic performance using a three-dimensional (3D) dynamic Finite Element Method (FEM) in accordance with current Japanese governmental guidelines. A detailed 3D model incorporating the dam body, surrounding topography, foundation, and reservoir was developed, and expected earthquake motions in three directions were applied simultaneously. The analysis showed that localized tensile stress exceeding the tensile strength occurred near the upstream heel of the dam base. However, these stress concentrations were limited to small regions and did not form continuous damage paths across the dam body. Based on the linear dynamic analysis and engineering judgment, the overall structural integrity and water storage function of the dam are considered to be maintained. Additional analyses were conducted by varying the elastic modulus of the foundation rock and dam concrete to clarify the influence of material stiffness on seismic response and stability. Full article

To address the difficulties in characterizing fine crack morphology, the limitations of detection accuracy, and the challenge of real-time deployment caused by large model parameter counts in concrete dam crack detection, this paper constructs DamCrackSet-1K, a high-resolution dataset with pixel-level annotations covering multiple crack scenarios; proposes a lightweight semantic segmentation framework, MTC-Net, which integrates a MobileNetV2 encoder with Enhanced Transformer modules to achieve global–local feature fusion and enhance feature extraction; and designs a geometry-sensitive Curvature-Aware loss function to effectively mitigate pixel-level class imbalance for fine cracks. Experiments show that, while significantly reducing the number of model parameters, the method greatly improves crack detection accuracy and inference speed, providing a feasible solution for efficient, real-time crack detection in dams. Full article

Fiber-Optic Sensors (FOSs) offer unprecedented performance for Structural Health Monitoring (SHM) of concrete dams, addressing the critical need for robust instrumentation. This study evaluates the capabilities of Raman-type Distributed Fiber-Optic Sensors (DFOSs) and Bragg grating-type Localized Fiber-Optic Sensors (LFOSs) for concrete temperature monitoring in a case study. Raman-type DFOSs offer superior spatial resolution and comprehensive thermal mapping, enabling the detection of detailed thermal phenomena, such as the cooling effects of dam galleries and significant thermal gradients, that conventional technologies cannot capture. They are also easier and faster to install, as they do not require trench construction. However, monitoring data acquisition can be more expensive with Raman-type DFOSs. Bragg-type LFOSs offer reliable localized measurements analogous to conventional thermometers. A key benefit is their multiplexing capability, which significantly reduces the total number of cables needed, making a complete LFOS-based monitoring system easier and potentially cheaper to install than an equivalent conventional system, even though individual LFOS installation still requires trenches. Overall, both FOS technologies are effective and reliable for concrete dam temperature monitoring, providing data quality comparable to conventional sensors and representing a significant advancement for SHM systems. Full article

This work focuses on the dynamic monitoring behaviour of concrete dams, with a specific emphasis on the Baixo Sabor dam as a case study. The main objective of the dynamic monitoring is to continuously observe the dam’s behaviour, ensuring it remains within expected patterns and issuing alerts if deviations occur. The monitoring process relies on on-site instruments and behaviour models that use pattern recognition, thereby avoiding explicit dependence on mechanical principles. The undertaken work aimed to develop, calibrate, and compare statistical and machine learning models to aid in interpreting the observed dynamic behaviour of a concrete dam. The methodology included several key steps: operational modal analysis of acceleration time series, characterisation of the temporal evolution of observed magnitudes and influential environmental and operational variables, construction and calibration of predictive models using both statistical and machine learning methods, and the comparison of their effectiveness. Both Multiple Linear Regression (MLR) and Multilayer Perceptron Neural Network (MLP-NN) models were developed and tested. This work emphasised the development of several MLP-NN architectures. MLP-NN models with one and two hidden layers, and with one or more outputs in the output layer, were performed. The aim of this work is to assess the performance of MLP-NN models with different numbers of units in the output layer, in order to understand the advantages and disadvantages of having multiple models that characterise the observed behaviour of a single quantity or a single MLP-NN model that simultaneously learns and characterises the observed behaviour for multiple quantities. The results showed that while both MLR and MLP-NN models effectively captured and predicted the dam’s behaviour, the neural network slightly outperformed the regression model in prediction accuracy. However, the linear regression model is easier to interpret. In conclusion, both methods of linear regression and neural network models are suitable for the analysis and interpretation of monitored dynamic behaviour, but there are advantages in adopting a single model that considers all quantities simultaneously. For large-scale projects like the Baixo Sabor dam, Multilayer Perceptron Neural Networks offer significant advantages in handling intricate data relationships, thus providing better insights into the dam’s dynamic behaviour. Full article

The production of concrete strongly influences the environment. It is a versatile and sustainable construction material capable of creating a wide range of structures. It has always been indispensable as a material for the engineering and construction industry, including applications in hydraulic structures (e.g., dams, underwater tunnels, sluices, and other concrete structures), where mass concrete is a fundamental material in the construction industry. Developing sustainable concrete as an alternative construction material to the traditional one provides a reduction in the carbon dioxide footprint with regard to cement use and waste material disposal in landfills. This paper provides a comprehensive review of current trends and opportunities in sustainable construction using mass concrete. It underscores the importance of incorporating eco-friendly practices to mitigate environmental impact by using by-products as green materials. The review highlights how optimizing clinker content, supplementary cementitious materials (SCMs), and aggregates can improve the strength, durability, and thermal stability of mass concrete. Strategic material selection helps minimize thermal cracking, extend service life, and reduce environmental impact. Future research should focus on developing advanced mix design strategies and standardized practices for sustainable infrastructure. Full article