Dam Section Research Articles

Centrifuge model studies on the performance of earthen dams with geocomposite internal drain subjected to pseudostatic seismic loading

This paper evaluates geocomposite (GC) as an internal drain for seepage control in earthen dams subjected to upstream impoundment and inertial loading through centrifuge model tests. A total of five centrifuge tests were performed on a homogeneously built small earthen dam section having prototype height of 7.2 m with 1H:1V side slopes at 30 g-level using a 4.5 m radius large beam geotechnical centrifuge available at the Indian Institute of Technology Bombay, India. The studied earthen dam models had an internal drain in the form of (a) a geocomposite horizontal drain (GC HD); (b) a sand-sandwiched geocomposite horizontal drain (SSGC HD); (c) a geocomposite chimney drain (GC CD); and (d) a sand-sandwiched geocomposite chimney drain (SSGC CD). The seepage-deformation response of the GC equipped earthen dam models is presented in terms of the development of pore-water pressure (PWP), phreatic surfaces, surface settlements (sc), and downstream slope face movements (sf). The behavior of the earthen dam model without any internal drain is also presented for comparison. In the case of an earthen dam with GC internal drain both as HD and CD, it was found to be efficient up to some extent in restricting phreatic surfaces, but phreatic surfaces were observed to be close to downstream side slope. However, a sand-sandwiched GC internal drain HD and CD seemed more promising in restricting the phreatic surface much within the downstream region and imparting higher stability even during sustained inertial loading conditions. The study concludes that SSGC chimney drain can be safely adopted for seepage control in small earthen dams and similar geotechnical structures viz levees, raw water reservoirs (RWRs), coastal protection structures, etc.

Versions of the drainage area ratio method for transfer of daily or monthly stream flows

Using the drainage area ratio (DAR) method, daily or monthly flows gauged at a nearby station are transferred to an ungauged section where a dam is to be built by multiplying them by a real number resulting from raising the ratio of the drainage areas of the dam section and of the station to an exponent n. Commonly, n is taken as 1. Using the daily flows of two stations nearby a dam section on the same stream or a neighbouring stream, having a common N-year-long gauging record, it is proposed that 365 linear regressions be fitted to N pairs of 365 daily flows and relate them to the DARs. The daily flows at the dam section can then be computed using 365 values of n' each belonging to 1 day. Next, using the same analytical model applied to monthly flows, 12 monthly flows are transferred to the dam section. Five versions of the DAR method – three of which have constant exponents – were investigated. The method with n = 1 was found to be the worst performer.

Исследование влияния режима работы ГЭС на перераспределение фитопланктона в верхнем водном слое в приплотинном участке Горьковского водохранилища

Исследование влияния режима работы ГЭС на перераспределение фитопланктона в верхнем водном слое в приплотинном участке Горьковского водохранилища

Analysis of the field studies of the foundation deformations and total draft of the Boguchansk HPP concrete dam

The results of data analysis from complex field studies of vertical deformations of the rock base near-contact layer and full settling Boguchanskaya HPP concrete dam sections in order to determine the state of contact of the foot of the concrete dam with the rock base are presented. The purpose of the study is to control the state of the contact of the concrete dam foot with the foundation based on the analysis of a set of field studies of the vertical deformations of the near-contact zone of the foundation of the concrete dam sections and the total draft of the sections of the concrete dam to justify the stability of the concrete dam sections. In order to control the vertical deformations of the near-contact zone of the rock foundation, string control and measuring equipment (displacement sensors PLPS-10) was installed. The total draft of the concrete dam sections is measured by means of ceiling marks installed in the grout gallery. Analysis of the field data on total drafts of concrete dam sections and vertical deformations of the near-contact section of the rock foundation showed that the contact joint between the foot of the concrete dam sections and the foundation is in vertical compression. The results of the analysis of the available data of complex studies of vertical deformations of the near-contact layer of the rock foundation and the total draft of the concrete dam sections made it possible to substantiate the stability of the concrete dam sections.

Stress-strain analysis and safety evaluation of concrete-faced rockfill dams

For concrete-faced rockfill dams with a medium dam height of a pumped storage power station, the gravel overburden of the dam site will be deep and the bedrock of the riverbed will be inclined downstream. Under complex topographic and geological conditions, the deformation control of the dam and the stability of the dam slope will be very important to the safe operation of the dam. Therefore, based on the Tsinghua nonlinear decoupled K-G model of rockfill materials, in this work, we adopted the finite element method for simulating and calculating the stress and deformation characteristics of typical dam sections in the construction and storage periods, and we carried out parameter sensitivity and comparative analyses with the Shen Zhujiang double yield surface and Duncan Chang E-B models. According to the findings, the distribution of stress and deformation of the dam were reasonable and conformed to the distribution law of a rockfill dam built on a slope. The maximum horizontal displacement occurred in the middle of the compressible layer near the downstream, the maximum settlement occurred in the middle of the compressible layer, and the maximum value of the panel deflection occurred at about 1/2 of the dam height. In addition, the dam material modulus exerted little impact on the dam stress but had an obvious effect on the deformation of the dam body and face plate. The stress values of the dam body calculated by the different constitutive models showed little difference. Although the distribution law of displacement was almost the same, the magnitude difference was large. Our research results may serve to be a reference for the stress and deformation analysis and engineering design of concrete-faced rockfill dams.

Calculation and Analysis of Temperature Damage of Shimantan Concrete Gravity Dam Based on Macro-Meso Model.

Considering that ANSYS software will automatically quit or the computer will freeze when generating random aggregate models of concrete by using some existing methods that are based on the ANSYS parametric design language (APDL), a new method of random aggregate placement using the ESEL command in APDL and the rotation of the local coordinate system is proposed in this paper. According to this method, a multiscale macroscopic and mesoscopic finite element model of the No. 9 non-overflow dam section of Shimantan dam is constructed. In addition, considering that most of the damage models adopted by the existing mesoscale simulation of concrete damage and fracture cannot take into account the interaction between aggregates, interfacial transition zone (ITZ), and mortar, an improved anisotropic temperature damage model is proposed in this paper. The aggregate placement simulation results show that the method presented in this paper can quickly generate two-dimensional (2D) random concrete aggregates, and the generation of three-dimensional (3D) aggregates can also be completed in a very short time, which can greatly improve the aggregate generation efficiency. Moreover, the aggregate shape generated by this method is very close to the real concrete aggregate shape. The crack propagation simulation results show that the sudden rise and fall of temperature can cause damage in the mortar and ITZ of concrete inside the dam body, which is the main reason for the generation of macroscopic through-cracks in the No. 9 non-overflow dam section of Shimantan dam during the operation period. Finally, it can be learned from the results that the method presented in this paper is reasonable and feasible, and can be extended to the crack propagation simulation of some other concrete gravity and arch dams.

Functional zoning optimization design of cemented sand and gravel dam based on modified Duncan-Chang nonlinear elastic model

Cemented sand and gravel is widely used in water conservancy project construction due to its advantages of low material consumption, strong adaptability and environmental protection. Due to the single design of the dam section, its application scope is limited. Aiming at the design problem of the cemented sand gravel dam section, In this paper, the modified Duncan-Chang nonlinear elastic model is used as the constitutive model of dam material, and the design concept of dam functional zoning is combined with the mechanical properties of Cemented sand and gravel dam material to propose the optimal design scheme of functional zoning in line with the CSG dam. The Tobetsu dam in Japan is used as a prototype for finite element optimization design analysis, and the analysis results are compared with the engineering data. The results show that: (1) The optimized scheme changes the upstream slope to 1:0.34 and the downstream slope to 1:0.77 under the condition of ensuring the safe operation of the dam, which reduces the amount of cementitious admixture per unit dam section by 34.2% and 23.6% respectively, significantly reducing the amount of cementitious materials used, in line with the concept of optimal design; (2) The vertical stress of the dam body is compressive stress during the completion period, but both during the operation period, the location of the dam heel appears; (3)The upstream side of the dam axis should have a large modulus of deformation during the operation period, and the modulus of deformation can be reduced from upstream to downstream in order to ensure that the dam deformation is coordinated after water storage.

Evaluation of Seepage on the Right Side of Haditha Dam, West of Iraq

The study aims to assess the water seepage through the right side of Haditha dam structures in western Iraq, using the finite elements method by an advanced computer software (SEEP/ W, 2012), the earth fill dam is 9 km long on the Euphrates River. Many attempts were done to ascertain the results of the program on a supposed earth dam and compare the results with the other analytical methods. The comparison reveal to very close results, and this indicate the suitability of the software for Haditha dam structures seepage analysis. After the verification of the results, then the real design information of the dam was input to analyse the dam, the input data are the height of the dam, width, slope of upstream and downstream, dimensions of the core, hydraulic conductivity of the different materials of the dam and the foundations. The results obtained from the SEEP/W2012 software were compared with the actual field data of the seepage amount for years (1989 - 2017) and with the water level in the dam reservoir for different periods. The result of comparison gave an idea to the efficiency of the dam protection against the seepage.Through the SEEP/ W data, which simulates the dam sections, levels and discharges that calculated by the software, which is compatible with the field monitoring data, it can be said that the software was able to simulate the actual conditions of the dam and identify the weakness zones. Where the results displayed that the asphaltic diaphragm in good condition and efficient on the right side of the dam. The grouting curtain in the right side is efficient, except for the area between the two stations 15 and 25, the zone between two stations need a continuous monitoring. The results also reflect that earth fill materials and the central core of the dam are efficient, and seepage within permissible design values.

Seismic Safety Review of Gravity Dam Based on Finite Element Method

With the change of the seismic parameter zoning map of China (GB 18306-2015), the seismic grade of reservoir dams in some areas had changed. At the same time, the standard for seismic design of hydraulic structures (GB 51247-2018) also put forward new requirements for the seismic calculation of reservoir dams. In order to ensure the safe operation of reservoir dams, it is necessary to review the seismic safety based on the finite element numerical simulation technology. Taking the retaining dam section of a gravity dam as an example, a finite element model of the retaining dam section was established, the corresponding calculation and analysis of ground motion were carried out using the mode decomposition response spectrum method, and the seismic safety evaluation of the retaining dam section was carried out according to the calculation results. The results show the following: (1) after considering the effect of hydrodynamic pressure, the natural frequency of the dam body has been significantly reduced, and the first-order natural frequency has been reduced by about 10%; (2) in addition to the local tensile stress at the dam heel, the rest of the vertical stress on the foundation surface of the retaining dam section is compressive stress, and the length of the tensile stress is less than the distance from the dam heel to the curtain center line, which met the requirements; (3) the antisliding stability safety factor of the retaining dam section is greater than the design value in the specification and meets the safety requirements; and (4) the seismic safety of the retaining dam section meets the standard requirements, and the seismic grade is evaluated as grade A.

Holocene Environmental Evolution Response to the Human Activities and East Asian Summer Monsoon Variation in the Liangzhu Ancient City Complex, Eastern China

The Liangzhu Ancient City Complex is located in a low-lying coastal delta area, and its environmental evolution would have had a significant impact on the human-environment interactions. In this study, element geochemistry and grain size of the sediment sequence from a dam section in Ganggongling (GGL) reveal crucial aspects of sedimentary dynamics, environmental evolution, human activities, and East Asian Summer Monsoon(EASM) variation in the Liangzhu area since 5500 a. Starting from the middle-to-late Holocene, the GGL section shows an overall transition from warm humidity to cold-dry, which is consistent with the climate record dimension in southern China. Through comprehensive analysis of the sedimentary environment before and after the dam’s completion, it can be found that the Ganggongling dam has played a positive role in regulating mountain torrents and met the needs of production and domestic water, such as rice planting through water storage. Further applications on the multi-decadal to centennial time scale demonstrate that variations in solar activity may control the EASM intensity mainly in southern China, which is subject to ENSO intensity changes.

Analysis and research on sluice gate flow of a hydropower station under different working conditions

The rationality design of the sluice gate directly influences the flood control capacity of hydropower stations. To demonstrate the rationality of the creation of the spillway gate of a hydropower station in the Yellow River Basin, this paper adopts the method of combining model test with a mathematical model to study the pressure, flow velocity, and water level changes of the spillway gate of the hydropower station under the working conditions of check flood and design flood. The research results show that there is no negative pressure in the whole flood discharge sluice dam section under check flood and desert flood conditions. The pressure characteristics of each area of the sluice floor are good, and the velocity distribution is uniform. However, the outflow velocity of the reinforced cage section is greater than the anti-scour velocity of the river under the two working conditions, which impacts the downstream river, so it is necessary to increase the length of the reinforced cage section appropriately. The water flow falls twice in the spillway dam section. The initial position of the first fall is the same under two working conditions. However, the falling depth decreases with the decrease of reservoir water level. The second fall position moves backward with the reduction of the water level. This paper provides a theoretical reference for the demonstration of flood discharge capacity of other hydropower stations through the analysis and research of the flood discharge sluice state of this hydropower station.

Design optimization of non-overflow section of a concrete gravity dam

Design optimization of non-overflow section of a concrete gravity dam

Gravity dam analysis using particle swarm optimization method

Structural stability analysis is the key aspect of a gravity dam. The safety of a dam relies on its capabilities to handle all external static and dynamic forces acting on it. This study includes stability analysis of a non-overflow section of gravity dam using the Particle Swarm Optimization (PSO) method. PSO method is applied for stability analysis of gravity dam as it has very few parameters to adjust during analysis. Structural stability analysis is performed on a 23.375 m high non-overflow section of the gravity. The analysis of the dam was carried out having a height to width ratio of 1.171, which comes under seismic zone II. The safety checks results obtained graphically presented for the accuracy using PSO satisfy structural safety evaluation limits as per specified in IS 6512. In other preferred conventional methods is difficult and time-consuming to find an error and fix it compared to PSO. PSO provided an efficient and accurate solution and presented as a point or be extended to n-dimensional space. The structural stability safety checks results are graphically presented for the accuracy of manual calculations.

Topological optimisation technology of gravity dam section structure based on ANSYS partial differential equation operation

Abstract This paper uses the finite element method to explain the specific nature of numerical instability such as network dependence in the topology optimisation of engineering structures from the perspective of partial differential equations. Gaussian function filtering method reduces the global impact of local extremum on topology optimisation. Finally, the method is introduced into the topology optimisation of concrete gravity dams in hydraulic engineering, and the topology optimisation program is developed in conjunction with ANSYS software language to achieve the topology optimisation of building structures in hydraulic engineering from a technical perspective.

System reliability of a gravity dam-foundation system using Bayesian networks

Traditionally, the reliability of a gravity dam-foundation system is evaluated using several typical dam sections. However, the performance of different dam sections may vary greatly even under the same environment and loading conditions due to the different dam structures and geological conditions. Therefore, an improved method was proposed in this study to assess the system reliability of a gravity dam-foundation system more reasonably. Based on the synchronous load increment in the whole dam and the response surface method (RSM), the critical failure modes were determined, and the RSM agent models for the strength failure and instability failure performance functions were constructed. Through the Monte Carlo simulation and the Bayesian progressive deduction, the method of system reliability was proposed. The application results of a gravity dam showed that the reliability in different dam sections was different for the same loading and environment conditions, and the system safety assessment was unreasonable using several typical dam sections. The proposed method overcame the defects of excessively searching the failure path, distorting the failure probability assessment, and incompletely describing the characteristics of the system using the traditional methods. It provides a new method for the system reliability evaluation of large-scale and complex structural systems.

Study on seismic safety of Poshitougou flood intercepting dam

Poshitougou dam is located in Xichang City, Sichuan Province. The purpose of the dam is to divert the river section passing through the open-pit mining site to ensure the safe operation of the mining site. The dam is a concrete gravity dam with a length of 148.61m and a height of 34.0m, built on deep alluvium foundation with a depth of 160m. The nearest distance between the dam and the Anninghe fault is 10km, and the fault may have a magnitude 7.5 earthquake in the future, so the seismic safety of the dam is very important. In this paper, the finite element dynamic method is used to analyse the seismic response and dam safety under the design earthquake. According to the calculation results, there are serious potential safety hazards in the dam under strong earthquake, including: collision between adjacent dam sections may occur during the earthquake, causing local damage to the concrete near the joint; joint deformation may tear the water stop, leading to dam leakage; breakage of dam foundation curtain grouting may occur during the earthquake. This paper also discusses the possibility of constructing hardfill dam on deep alluvium foundation in strong earthquake area. The calculation results show that the seismic displacement of the hardfill dam is obviously reduced, the seismic amplification effect of the dam is significantly reduced, the dynamic stress of the dam is smaller and its seismic performance is good.

Algal Boom Characteristics of Yeongsan River Based on Weir and Estuary Dam Operating Conditions Using EFDC-NIER Model

A number of hydraulic structures have been installed along the Yeongsan River, including an estuary dam and two weirs (Seungchon and Juksan). While these structures aid in regional water security and use and reduce flooding, they reduce water flow in the summer, thereby frequently causing algal blooms. This study simulated algal bloom and water quality characteristics of sections of the Yeongsan River in South Korea under different weir and estuary dam operating conditions using the Environmental Fluid Dynamics Code—National Institute of Environment Research (EFDC-NIER) model. Results showed that when the management levels of the Juksan Weir and estuary dam were maintained, simulated water levels were EL. 3.7 m in the weir section and EL. −1.2 m (below average water level of the Yellow Sea) in the dam section. When both the weir and dam were open, the water levels varied with the tide; in contrast, when the Juksan Weir alone was open, the water level was between EL. −1.2 and −0.9 m, in line with the management level of the estuary dam. Opening the weir alone reduced algal blooms by 72–84% in the weir region, and opening the estuary dam alone reduced the algal blooms by 83% in the dam region. This improvement was attributed to the reduced water retention time and dilution due to seawater inflows.

Numerical analysis of a zoned earth dam considering hydrodynamic force during the earthquake excitation

This paper presents finite element analysis of a zoned earth dam considering hydrodynamic force during the earthquake. Geostudio software using the sub-program SEEP/W and QUAKE/W was used. The earthquake that is used in this analysis are Iraqi earthquake that happened in Ali Al-Garbi within Missan governorate and El-Centro earthquake. Haditha dam section was used for the hypothetical dam. The maximum height of the dam is 57 m. The shell was constructed from the mix of sand-gravel with the average particles diameter range from (0.24 to 16.7 mm). Three different properties were used for core material, each one of these properties was analyzed under three different heads of water in the upstream side. The main parameters that have the influence on the analysis results are; water level in the upstream side of the dam, intensity of the earthquake, properties of the core material, and the value of hydrodynamic force. The hydraulic flux and peak displacement increase with increasing these parameters.

Temperature Field Online Reconstruction for In-Service Concrete Arch Dam Based on Limited Temperature Observation Data Using AdaBoost-ANN Algorithm

Temperature is one of the factors affecting the safety operation of concrete arch dams. To accurately reconstruct the temperature field of the concrete arch dam online based on the temperature data of several typical dam sections, this paper proposes the AdaBoost-ANN algorithm. The algorithm uses artificial neural network (ANN) to establish a training set of the measured temperature data and the temperature field of the concrete arch dam obtained by the three-dimensional finite element model; these trained artificial neural networks are used as weak classifiers of the AdaBoost algorithm. Then, the AdaBoost-ANN algorithm is used to establish the mapping relationship between the measured temperature data and the temperature field, and the online reconstruction of the temperature field of the concrete arch dam is realized. The case study shows that the temperature field of the concrete arch dam can be accurately established by AdaBoost-ANN algorithm based on limited temperature observation data. The algorithm is more time-saving and labor-saving than the finite element method and is convenient for online reconstruction of the temperature field and assessment of the safety status of the concrete arch dam.

Seasonal variability of sulfate ions in the Volga River water

In the Volga River water, sulfate ions rank second among the main anions in terms of their contribution to water mineralization. To study the seasonal variability of sulfate concentration, an analysis of long-term data of hydrological and hydrochemical observations obtained on the River Volga (in the outlet section of the Kuibyshev reservoir) has been carried out. For the period of 2001-2018 the average annual water consumption in the dam section varied in the range of 6.2-9.0 thousand m3/s, the average annual concentration of sulfates was 55 mg/dm3, the highest - 64 mg/dm3, and the lowest - 45 mg/dm3. The content of sulfates in the reservoir is formed mainly under the influence of the Volga River water coming from the Cheboksary reservoir and the Kama River water coming from the Nizhnekamsk reservoir. The sulfate content is characterized by significant seasonal variability. During the winter low-water period, the highest concentrations of sulfates were observed with a maximum in April, before the beginning of the spring flood (67 mg/dm3). During the flood, the content of sulfates decreased, reaching the lowest values during the summer low-water period in August (44 mg/dm3), and then, from September, the concentration of sulfates gradually increased, reaching 57 mg/dm3 at the beginning of the winter low-water period. Over a long-term observation period, the amplitude of sulfate fluctuations was 34-87 mg/dm3, and its value depended on the water content of a particular year. In dry years, the concentration of sulfates in the water increased, and in dry years, it decreased. In the seasonal context, the main differences in sulfate concentrations in dry and high-water years occurred during the spring flood and winter low-water period, and during the summer - autumn low-water period, the differences became minimal.