Dam Section Research Articles

Assessment of Overflow Risk in Agricultural Reservoir Based on Water Balance Theory

The unexpected climate changes are causing rainfalls to exceed the design frequency, which complicates the management and operation of agricultural reservoirs and increases the risk of overflow. According to the “Planning and Design Standards for Agricultural Prediction Infrastructure Maintenance Project (Fill Dam Section),” agricultural reservoirs were originally designed without flood control functions, with the standard being to directly discharge incoming flood. Based on this foundation, this study assesses the overflow risk of agricultural reservoirs using the concepts of inflow and outflow theories as well as storage capacity. The balance when inflow and outflow are at their maximum was analyzed for prioritized areas, focusing on the flood management area (the area between the full water level and crest elevation) relative to the basin area, to examine the feasibility of balance through flood routing. The proposed method is easily accessible to facility managers, enabling them to assess the risk of reservoirs for efficient management and operation during floods.

Seismic Vulnerability Assessment of Non-Overflow Concrete Gravity Dam Section

Abstract As the economy advances, there is a growing need for energy. Harnessing hydroelectric energy has emerged as a crucial strategy for addressing the energy crisis. To promote hydropower development, numerous tall concrete dams are either under construction or in the planning stages. These dams are frequently situated in areas with elevated water levels and face the challenge of being located in regions with high seismic intensity. An accident resulting from the failure of concrete dams can pose significant threats to both economic development and public safety. Therefore, it is of crucial importance to investigate the stability of such dams, particularly under conditions of high water levels and seismic activity. The finite element program Geostudio is being undertaken to evaluate a complete numerical analysis of the dam. In this paper, Longtan Dam has been selected as the case study for the research. This study is applied in two cases: seismic and static conditions. A two-dimensional seismic numerical analysis was carried out using the Koyna earthquake acceleration time records in 1976. The results of the FEM model concluded that the dam is unsafe under sesmic conditions. The concrete-rock interface, particularly susceptible to sliding, was identified as the most critical part of the dam, presenting the most likely failure mode. The study highlights the significance of its methodology in investigating earthquake effects on dams, prioritizing it over the achieved results. The aim is for the conclusions and recommendations to provide valuable guidance for future studies and initiatives focused on enhancing safety at hydropower dams.

Temperature Control and Crack Prevention of High RCC Dam in Cold and Drought Area

A development process is introduced for a computation program to calculate the temperature and stress field of mass concrete based on the ANSYS® platform. The temperature control scheme of a high roller compacted concrete (RCC) dam in northern Xinjiang is optimized by using the simulation program. It is suggested that the concrete pouring temperature of the dam should not exceed 16°C and that water-pipe cooling should be adopted. The dam should be permanently heat preserved by 10 cm thick extruded polystyrene (XPS) extruded panels, and the top surface of the overwintering layer should be covered with an at least 14 cm thick thermal insulation quilt. During construction, the warehouse surface should be temporarily insulated with a 2 cm thick thermal insulation quilt. The causes of cracks in a particular dam section are simulated and analysed, and it is concluded that the cracks are mainly caused by the lack of thermal insulation of the warehouse surface during cold spells.

On the multi‐parameters identification of concrete dams: A novel stochastic inverse approach

AbstractThis paper introduces a novel stochastic inverse method that utilizes perturbation theory and advanced intelligence techniques to solve the multi‐parameter identification problem of concrete dams using displacement field monitoring data. The proposed method considers the uncertainties associated with the dam displacement monitoring data, which are comprised of two distinct sources: the first is related to stochastic mechanical properties of the dam, and the second is due to observation errors. The displacements at different measuring points generated by dam mechanical properties exhibit spatial correlation, while the observation errors at different points can be considered statistically random. In this context, the inversion formulas are derived for unknown stochastic parameters of the dam by combining perturbation equations and Taylor expansion methods. An improved meta‐heuristic optimization method is employed to identify the mean of stochastic parameters, while mathematical and statistical methods are used to determine the variance of stochastic parameters. The feasibility of the proposed method is verified through numerical examples of a typical dam section under different conditions. Additionally, the paper discusses and demonstrates the applicability of this method in a practical dam project. Results indicate that this method can effectively capture the uncertainty of dam's mechanical properties and separates them from observation errors.

Deformation Monitoring and Potential Risk Detection of In-Construction Dams Utilizing SBAS-InSAR Technology—A Case Study on the Datengxia Water Conservancy Hub

Deformation monitoring plays a pivotal role in assessing dam safety. Interferometric Synthetic Aperture Radar (InSAR) has the advantage of obtaining an extensive range of deformation, regardless of weather conditions. The Datengxia Water Conservancy Hub is the largest in-construction dam in China. To effectively assess the in-construction dam safety, the SBAS-InSAR (Small Baseline Subset-InSAR) technique and 86 Sentinel-1 images (from 11 February 2020, to 16 January 2023) have been employed in this study to monitor the deformation over the reservoir and its surrounding areas. The reliability of the SBAS-InSAR monitoring results over the study area was demonstrated by the in situ monitoring results. And the InSAR results show that the central section of the left dam exhibits the most substantial cumulative deformation, attributed to the maximal water pressure. This is closely followed by the left end of the dam, which reflects a similar but smaller deformation. However, the in-construction cofferdam facilities make the right-end section of the left dam more robust, and the deformation is the most stable. Additionally, significant deformation of the auxiliary dam slope has been identified. Moreover, the analysis indicated that the deformation of the four upstream slopes is closely related to the precipitation, which potentially poses a threat to the safety of the Datengxia Dam.

Thermal parameter inversion of low-heat cement concrete for Baihetan arch dam

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

Stability Assessment of the Dam of a Tailings Pond Using Computer Modeling—Case Study: Coroiești, Romania

Anthropogenic activities related to mining generate both progress and a vast amount of waste that is responsible for environmental degradation. The Jiu Valley is one of the areas of Romania where mining has affected large areas of land, used to build mines and tailings ponds. The former Coroiesti coal processing plant (CCPP) is such a location with a total area of 25 ha containing approximately 5.5 million tons of tailings. The assessment of the stability of tailings dams is extremely important from safety and environmental aspects. This study proposes a solution based on numerical methods for determining the stability of a section of the dam of a tailings pond. The model of tailings pond no. 1, compartment B, from the Coroieşti Coal Preparation was built using COMSOL Multiphysics. Two scenarios of stability analysis were conducted on a section of the tailings dam: the FOS was determined using the shear strength reduction (SSR) method for both the initial and the current state of this TP. This method is a modern alternative to the limit equilibrium method, and its implementation by COMSOL is new to our country, thus aligning this methodology with current worldwide trends and developments in the field. The results obtained proved to be in line with those calculated in the past with traditional analytical methods, proving that the safety criteria of the studied TP/TD are being met.

Study on the Disaster Mechanism Analysis and Enlightenment of Dam Failure

With the continuous advancement of infrastructure construction, dam, as an important water conservancy project, plays the role of water storage, flood regulation and power generation. However, due to the influence of extreme weather and other reasons, there may be the possibility of dam failure accidents when the dams are put into operation. The dam break accident may bring great losses to the downstream dam section. The theme of this paper is the disaster mechanism analysis and enlightenment of dam failure. By combining the statistics of dam break data with the analysis of potential causes, the disaster mechanism of dam break is obtained. According to the disaster mechanism, the corresponding treatment plan and future development trend are discussed, with the aim of monitoring the design, construction and operation stages of the dam. Suggestions for improvements include improving the dam's ability to withstand extreme weather, carrying out precise construction according to specific steps, and improving the professionalism of managers. These suggestions can reduce the probability of dam break accidents and reduce the casualties and economic losses caused by dam break accidents.

The probabilistic mechanical-material modeling of complex non-homogeneous structures using the coupling of isogeometric boundary element method and reliability approach

Describing mechanical fields with precision in engineering analyses can be a challenging task. Analytical solutions fall short for real complex problems. The widespread use of numerical methods to overcome this obstacle has increased along with the advances in computational capacity. For instance, in geotechnical and composite materials problems, the use of a numerical approach becomes indispensable in several situations. For large volume-to-boundary ratio problems or for non-uniform fields evaluation, the boundary element method is a suitable tool. The method is based on the boundary discretization and on solutions to boundary integral equations. Thus, this article introduces the isogeometric boundary element method formulation and explores techniques for enhancing its physical problem descriptions, specially focusing in geotechnical issues and description of body forces. Two numerical examples are presented. Firstly, a multi-material dam, inspired by the real Itaipu dam section, is analyzed and the results are compared to the well-known ANSYS® FEM software. Furthermore, the article presents a tunnel case study in which a reliability assessment is conducted to account for the inherent uncertainties in the problem. This assessment is accomplished using the improved Hasofer, Lind, Rackwitz e Fiessler-first-order reliability method algorithm, which provides insight into the structural failure risk.

A deep learning prediction model of DenseNet-LSTM for concrete gravity dam deformation based on feature selection

Dam deformation can comprehensively reflect the operational status of the dam. Thus, it is significant to build a dam deformation prediction model with high accuracy for the operation of concrete gravity dams. The concrete gravity dam is a complex and dynamic system. Based on the current prediction methods, such as the statistical models or machine learning (ML) models, it is a challenge to capture the complicated relationships between deformation and various features, as well as the features and time. As a result, we have proposed a deep learning model called DenseNet-LSTM, which combines the densely connected convolutional Network (DenseNet) and long short-term memory (LSTM) network. Meanwhile, correlation analysis and random forest (RF) are also adopted to evaluate and select deformation features. In the case study, the deformation monitoring data of multiple points at different elevations in the same section of a typical concrete gravity dam in southwestern China are selected to verify the model. For all the monitoring points, the correlation coefficient of the proposed model is more than 0.99. The result shows that the DenseNet-LSTM model can reveal the dynamic evolution process of deformation of the concrete gravity dam. Compared with the CNN-LSTM, LSTM, and ML-based models, the accuracy of the proposed model is higher and its generalization ability is better, which provides new methods for dam safety monitoring.

Case Study on the Method of Rock Mass Overburden Consolidation Grouting for Dam Foundation

Conventional grouting methods present challenges in achieving effective surface rock grouting and avoiding interference with concrete grouting and construction processes. The proposed approach includes reserving rock overburden, controlling grouting pressure and concentration, using a segmented grouting method, and selecting appropriate materials to develop a key method for consolidation grouting. This method not only overcomes the problems associated with the conventional consolidation grouting method but also effectively protects the thin layer of breccia lava in the Baihetan Dam foundation and solves the problem of unloading and relaxation of columnar jointed basalt caused by exposed consolidation grouting. The results show that the post grouting inspection hole permeability qualification rate is 99.3%, with the proportion of high-speed measuring points of various rock types ranging from 91.8% to 93.3%, and the proportion of low-speed measuring points ranging from 2.0% to 2.9%. The drop rate of the grout take of sequence I and sequence II is between 30%–60%, except for some dam sections. These results indicate that the proposed method for consolidation grouting meets the design requirements. The findings have significant implications for the design and construction of consolidation grouting in similar projects.

Investigation on Hydraulic Fracturing and Flexible Anti-Hydrofracturing Solution for Xiaowan Arch Dam

Understanding hydraulic fracturing in concrete super-high arch dams is vital for the implementation of safety measures on the bearing surface. In this study, we conducted tests on hydraulic fracturing for the Xiaowan arch dam (294.5 m) to analyze concrete behavior at cracks under various stress conditions. The risk of hydraulic fracturing near the dam heel was identified without compressive stress. Addressing this, we propose a flexible anti-hydrofracturing system using GB sealing material and a spray polyurea coating. Simulation tests on three schemes: ‘3 mm GB plate + 4 mm polyurea’, ‘1 mm GB glue + 5 mm polyurea’, and ‘7 mm polyurea’ showed effective prevention of hydrofracturing at concrete crack openings of 5 mm, 8 mm, or 10 mm under 300 m water pressure. Field tests supported ‘3 mm GB plate + 4 mm polyurea’ and ‘7 mm polyurea’ as optimal solutions for dam sections. Implementation involves a protective block layout with ‘3 mm GB plate + 4 mm polyurea’ on blocks and ‘7 mm polyurea’ in interval zones and corners. Since 2008, maximum leakage, including rock foundation, has remained minimal at 2.78 L/s under regular water levels. These insights aid similar concrete dams in optimizing safety systems.

Characteristics of Seismogenic Dust Particles from a Mountain and Their Significance for Paleoseismic Records in a Tufa Section: A Case Study of Jiuzhaigou, China

The sedimentary characteristics of the special interlayer contained in the section of the Sparkling Lake dam revealed by the 8 August Jiuzhaigou earthquake in 2017 are obviously different from the tufa in the dam body, and they are considered to be historic flood relics. Based on the study of the particulate matter from the 8 August Jiuzhaigou earthquake, this study combined comparative petrographic, mineralogical, geochemical, and chronological studies of the special interbedded sediments of the Sparkling Lake dam with other genetic samples to obtain homology information and genetic links and to explore the tufa depositional dynamics and earthquake disaster subsidence. The paleoseismic benefit in the discontinuity layer was explored, and the paleoseismic information embedded in the profiles was extracted, providing a new idea for reconstructing the paleoseismic events in the tufa deposition sequence. According to X-ray diffraction, laser particle size analysis, and scanning electron microscope experiments, the particulate matter in the Jiuzhaigou mountains has its own specific mineralogical characteristics. The mineral composition of the particulate matter is basically calcite. The particle size is large, and single particles are mostly angular and subangular. The fracture morphology observed under the single-particle microscope was uneven, showing the characteristics of the dust caused by earthquake disasters. The geochemical analysis data show that the distribution patterns of rare earth elements in different types of particulate matter in the same area have similar characteristics. Moreover, an analysis of the elements Rb, Sr, and Ba shows that the particulate matter in Jiuzhaigou has a strong correlation (R2 = 0.9941), indicating the stability and uniformity of the material source. The source of the particulate matter was limestone of the carbonate strata from the Devonian to the Triassic. Combined with mineralogy and grain size morphology, the interbedded particles in the tufa depositional profile have the potential application of paleoseismic archives to record extreme seismic events. According to the chronological data of the special interlayer sediments in the tufa dam body, the paleoseismic age is inferred to be 1220 ± 30 BP. Therefore, the tufa bedding can be related to the paleoearthquake, and the special interlayer of the tufa section can be used to reconstruct paleoearthquakes.

Deformation critical threshold estimation of Xiaowan ultrahigh arch dam with time-varying grey model

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

High Mobility and Flexibility in the Habitat Use of Early Juvenile Pikeperch (Sander lucioperca) Based on a Mark-Recapture Experiment

Disentangling the role of factors responsible for juvenile fish dispersal is essential to understand the ecology of individual species, setting the corresponding conservation status and evaluating the potential risk in case of invasion. Because of their small body size and high sensitivity to environmental conditions, juvenile fish movements have largely been explained by external factors such as wind-induced water currents. In this study, early hatched pikeperch (Sander lucioperca) of hatchery origin were marked with oxytetracycline hydrochloride, stocked into a bay near the dam of a deep reservoir, and then monitored at approximately 10-day intervals using fix-frame trawling for 43 and 51 days after stocking, in 2007 and 2008, respectively. In both years, marked pikeperch were captured throughout the study period in the bay and closed dam section of the reservoir. After one month, individuals were captured in the middle section of the reservoir, approximately 5 km upstream from the stocking site. Four individuals were recaptured in the tributary section of the reservoir, about 10 km upstream from the stocking site during the last sampling in 2007. The farthest distance detection followed periods of strong wind. During daytime sampling, marked pikeperch were captured in both the warm epipelagic layer above the thermocline and the cold bathypelagic layer below the thermocline. The later sampling represented a community of vertically migrating individuals originally thought to consist only of reservoir-born and reservoir-experienced fish. This study suggested the high mobility and flexibility of 0+ pikeperch, as well as their unexpected behavioral plasticity.

Automatic Concrete Dam Deformation Prediction Model Based on TPE-STL-LSTM

Concrete dam deformation prediction is important for assessing the safety of dams. A TPE-STL-LSTM deformation prediction model for concrete dams is established by introducing the TPE algorithm based on the decomposition–prediction model. Taking the Wanjiazhai gravity dam project as an example, a prediction model for the top deformation of 14 dam sections was established and the parameters were determined. The model was used for deformation prediction and compared with the measured deformation and similar methods to predict deformation for verification. The results show that the model has good prediction effect and matches well with the measured data; the accuracy is better than the Autoregressive Integrated Moving Average model and the Support Vector Machine model; and the model achieves the automatic determination of all parameters. The model can be used for dam engineering safety assessment, effectively improving the analysis accuracy and analysis efficiency.

Modal Analysis of Chushandian Gravity Dam

This article uses the finite element software ABAQUS to establish a three-dimensional finite element model based on the overflow dam section 12 # ~15 # and surface outlet dam section of the Chushandian gravity dam. The stress and displacement distribution of the 12 # ~15 # dam section of the Chushandian gravity dam under normal water storage level are analyzed; On this basis, modal analysis is conducted on the 12 # ~15 # dam section to study the impact of the dam's own modal conditions on the normal operation of the dam. The research shows that: (1) Under the condition of normal height water level, there is a small tensile stress at the dam heel, and the compressive stress at the dam toe is within the normal range. There is significant stress at the intersection of the upper curved part of the overflow dam and the transverse joint. The dam body strength meets the requirements and can be considered safe for the reservoir. (2) Modal analysis of the model reveals that significant deformation can occur at the right side of the dam crest during lower frequency vibrations. With the increasing frequency, the easily deformed parts of the dam are still at the top of the dam, and the displacement of the easily deformed parts is increasing. The position of the easily deformed parts is moving along the Dam axis, and the deformation direction of the easily deformed parts will change regularly.

Probabilistic finite element analysis of failures in concrete dams with large asperities in the rock–concrete interface

Common analytical assessment methods for concrete dams are unlikely to predict material fracture in the dam body because of the assumption of rigid body behavior and uniform- or linear stress distribution along a predetermined failure surface. Hence, probabilistic non-linear finite element analysis, calibrated from scale model tests, was implemented in this study to investigate the impact of concrete material parameters (modulus of elasticity, tensile strength, compressive strength, fracture energy) on the ultimate capacity of scaled model dams. The investigated dam section has two types of large asperities, located near the downstream and/or upstream end of the rock–concrete interface. These large-scale asperities significantly increased the interface roughness. Post-processing of the numerical simulations showed interlocking between the buttress and the downstream asperity leading to fracture of the buttress with the capacity being determined mainly by the tensile strength of the buttress material. The capacity of a model with an asperity near the upstream side, with lower inclination, was less dependent on the material parameters of the buttress as failure occurred by sliding along the interface, even with inferior material parameters. Results of this study show that material parameters of the concrete in a dam body can govern the load capacity of the dam granted that significant geometrical variations in the rock–concrete interface exists. The material parameters of the dam body and their impact on the capacity with respect to the failure mechanism that developed for some of the studied models are not commonly considered to be decisive for the load capacity. Also, no analytical assessment method for this type of failure exists. This implies that common assessment methods may misjudge the capacity and important parameters for certain failure types that may develop in dams.

Causes of Ponding in Foundation Gallery of Fenhe Reservoir II Gravity Dam

The multi field coupling mechanism of seepage, stress and temperature coupling of concrete gravity dam is analyzed, and its coupling control equation is deduced. Based on the analysis of the temperature effect of cracked concrete dam, a three field coupling model of seepage, stress and temperature based on pore crack dual medium suitable for the characteristics of RCC gravity dam is established, and its implementation strategy in COMSOL Multiphysics is studied. The three-dimensional finite element model of the overflow dam of Fenhe Reservoir II is established, and the annual working behavior of the overflow dam section is simulated in COMSOL Multiphysics. The variation law of dam seepage characteristics under the coupling action of seepage, stress and temperature is obtained. It is considered that the ponding in the gallery mainly comes from the crack leakage, and the temperature and headwater elevation are the main factors affecting the crack leakage of the dam.

Shear, Consolidation Characteristics and Carbon Footprint Analysis of Clayey Soil Blended with Calcium Lignosulphonate and Granite Sand for Earthen Dam Application

Soil is a composite material of great interest to civil engineers. When the quality of such composite soils is poor, ground improvement techniques must be adopted to withstand the design load of superstructure. Existing soil stabilizers include lime and cement; however, their environmental safety and sustainable use during stabilization have been receiving increasing attention in recent years. This study investigated the use of granite sand (GS) and calcium lignosulphonate (CLS) as sustainable stabilizers that could be blended with clayey soils. The considered dosages of GS were 30%, 40% and 50%, and those of the CLS were 0.25%, 0.5%, 1% and 1.5%. Direct shear and consolidation tests were performed on the GS–CLS blended soil samples that were cured for 7 and 14 days. The amended stabilizers improved the shear parameters and consolidation characteristics at an optimum dosage of 30% GS and 0.5% CLS. Maximum improvements of 84% and 163% were observed in the cohesion and angles of internal friction, respectively. A significant change was also observed in the consolidation characteristics, making them practically applicable. The soil hydraulic conductivity was reduced by 14%, and the coefficient of consolidation increased by 203% for 30% GS and 05% CLS. Carbon footprint analyses were performed on the soil composition that would be best-suited for a typical homogenous earthen dam section. The results showed that the use of GS and CLS together reduced the carbon emissions by 6.57 and 7.7 times, compared to traditional stabilizers, such as cement and lime.