Earth-rock Dam Research Articles

Study on seismic wave propagation regularity and dam-foundation interaction characteristics of earth-rock dam on deep overburden

Many dams have to be constructed on deep overburden in meizoseismal areas, so it is vital to understand the seismic performance of these dams. Current research primarily focuses on the whole seismic response of dams, in which the analysis can be relatively imprecise. Nevertheless, an in-depth understanding of the propagation regularity of seismic waves in earth-rock dams on deep overburden, as well as the interaction characteristics between the dam and overburden, is critical. In this paper, based on a planning soil core wall dam with over 500 m of overburden, the seismic wave input method is employed to conduct a detailed and in-depth study from the perspectives of the spatial distribution of seismic acceleration and the Fourier spectra of acceleration time history. The results indicate that the spatial distribution of the peak acceleration of the dam is significantly inconsistent. The horizontal peak acceleration of the upstream side of the dam is greater than that of the downstream side because the dynamic modulus of the dam is significantly inconsistently distributed. In addition, the amplification behaviours of the seismic wave are different in the overburden and dam body, and the low-frequency and high-frequency components are amplified. The dynamic interaction between the dam body and the overburden significantly reduces the acceleration response at the dam-foundation interface by 44 % and 50 % in horizontal and vertical accelerations, respectively, because of the absorption of seismic wave energy by the dam body and the inconsistency of the dynamic modulus distribution of the overburden. The findings of this study provide robust theoretical support for evaluating the seismic performance and designing measures for the seismic resistance of earth-rock dams on deep overburden.

Dam Surface Deformation Monitoring and Analysis Based on PS-InSAR Technology: A Case Study of Xiaolangdi Reservoir Dam in China

The Xiaolangdi Dam is a key project for the control and development of the Yellow River. It bears the functions of flood control, controlling water and sediment in the lower reaches, ice prevention, industrial and agricultural water supply, power generation, and so on. Its safety is related to people’s life and property safety and local economic and social development. It is of great significance to carry out comprehensive and regular deformation monitoring for dams since the deformation is an important evaluation index for dam safety. Interferometric Synthetic Aperture Radar (InSAR) technology has been a rapidly evolving technology in the field of space geodesy in recent years. It offers advantages such as high monitoring precision, extensive coverage, and high monitoring point density, making it a powerful tool for monitoring deformations in hydraulic engineering projects. Based on Sentinel-1 data covering the Xiaolangdi Dam from September 2020 to November 2022, the PS-InSAR technique was used to obtain the surface deformation of the Xiaolangdi Dam, and reservoir water level data on image acquisition dates were obtained for joint analysis. The results show that there is a large deformation in the center of the dam crest of the Xiaolangdi Dam, while both sides of the slope and downstream dam foot are relatively stable. The time series deformation of the dam body is closely related to the reservoir water level change. When the water level increases, the dam body tends to deform downstream; when the water level decreases, the dam body tends to deform upstream. The deformation and water level of the Xiaolangdi Dam exhibit a clear negative correlation. There is no significant cumulative deformation on the dam slopes or at the base of the dam. However, cumulative deformation occurs over time in the central area of the dam’s crest. The deformation process at the central area of the dam’s crest follows a continuous and non-disruptive pattern, which is consistent with the typical deformation behavior of the Xiaolangdi earth–rock dam structure. Therefore, it is judged that the current deformation of the Xiaolangdi Dam does not impact the safe operation of the dam. InSAR technology enables the rapid acquisition of high-precision, high-density deformation information on the surfaces of reservoir dams. With an increasing number of radar satellites in various frequency bands, such as Sentinel-1 and TerraSAR-X, there is now an ample supply of available data sources for InSAR applications. Consequently, InSAR technology can be extended to routine monitoring applications for reservoir dam deformations, especially for small and medium-sized reservoirs that may not be equipped with ground measurement tools like GNSS. This holds significant importance and potential for enhancing the safety monitoring of such reservoirs.

Three-dimensional reliability stability analysis of earth-rock dam slopes reinforced with permeable polymer

Polymer is a new repair and reinforcement material for earth-rock dams developed in recent years. Models are developed where spatial variability is incorporated into the analytical framework to evaluate the stability and reliability of reinforced three-dimensional dam slopes. The Karhunen-Loeve (K-L) expansion method is employed to generate three-dimensional random fields. The simplified Bishop method and Monte Carlo method are used to calculate the safety factors and failure probabilities of the dam slopes. With the implementation of polymer grouting reinforcement, the safety factors are improved and the failure probabilities are reduced. The reinforcement effect will be affected by the amount of polymer dosing, dam slope characteristics, and polymer grouting parameters. The impact of various longitudinal autocorrelation distances on reliability is influenced by the length of the dam slope itself. An increase of the safety factor by approximately 37% can be achieved through a polymer dosing of around 3%. Nevertheless, with the elevation of dam slope height and slope ratio, the effectiveness of polymer reinforcement is diminished.

Experimental Investigation and Field Evaluation of Anti-Scouring and Protection Material of Earth-rock Dam

Earth-rock dams have important flood control, silt reduction, water supply, and ecological benefits, but extreme rainstorms seriously threatens the safe operation of earth-rock dams. Therefore, based on the self-developed soil stabilizer, the laboratory tests and field evaluation tests for the anti-scouring performance for solidified soil were carried out to achieve the requirements of non-collapse or slow-collapse for the earth-rock dams. Firstly, the basic performance indexes of solidified soil using soil stabilizer and 42.5# P.O Portland cement were compared. Then, clear water scouring and muddy water scouring tests were carried out based on the self-developed anti-scouring test system. Furthermore, an earth-rock dam test dam was built by using the solidified soil as the material, and a field scouring test was carried out to analyze the corresponding hydraulic elements. Finally, a safety inspection of the dam structure was carried out. The results demonstrate that when compared to the results of solidified soil using 42.5# P.O Portland cement under the same contents, the strength and durability of soil stabilizer solidified soil rose by more than 5% and 10%, respectively. The performance of soil stabilizer is better than that of 42.5# P.O Portland cement. After 10 hours of approximately 15 m/s water flow scouring through the experiment test, the performance of the solidified soil under the higher content of soil stabilizer can meet the design requirements of anti-scouring performance. The field test results show that the maximum scouring depth is less than 2 cm, and the average scouring depth is less than 0.8 cm. The monitoring results show that the displacements are less than 5 mm, and the dam structure is safe and stable. It is recommended that the content of soil stabilizer should be higher than 20% to meet the overflow safety requirements of small and medium earth-rock dams.

Key technologies and future development trends of intelligent earth–rock dam construction

Key technologies and future development trends of intelligent earth–rock dam construction

Seismic Response of Earth-Rock Dams with Innovative Antiseepage Walls on the Effect of Microscopic Fluid-Solid Coupling

In dykes and dam projects, the microscopic fluid-solid coupling effect from the interaction between soil skeleton and pore water during an earthquake is crucial to consider, as it can lead to dam safety problems. To control seepage in medium- and small-sized dams, polymer antiseepage walls have emerged as effective measures. In recent years, this method has been increasingly utilized in projects worldwide as it is essential for preventing potential dam safety issues. To address concerns related to seismic safety, this study conducts theoretical analysis, model tests, and numerical simulations to investigate the seismic response of earth-rock dams with polymer antiseepage walls, with a specific focus on the microscopic fluid-solid coupling effect. The dynamic viscoelastic constitutive model used in this study incorporates Biot’s theory of dynamic consolidation and the results of dynamic mechanical analysis (DMA) of polymer materials. To validate the model, a centrifuge test is performed, and it is then utilized to study the seismic response of earth-rock dams with polymer antiseepage walls. Furthermore, the influence of factors such as fluid-solid coupling, water level, polymer material density, and wall thickness on the seismic response of dams with antiseepage walls is analyzed. Finally, the seismic safety of the earth-rock dam with the polymer antiseepage wall is thoroughly examined. The results emphasize the need to consider the fluid-solid coupling effect, as factors like water level and design parameters of the antiseepage wall significantly impact the seismic response of earth-rock dams with polymer antiseepage walls.

Investigating Deformation Mechanism of Earth-Rock Dams with InSaR and Numerical Simulation: Application to Liuduzhai Reservoir Dam, China

Ground deformation is the direct manifestation of the earth-rock dam's hazard potential. Therefore, it is essential to monitor deformation for dam warning and security evaluation. The Liuduzhai Dam, a clay-core dam of a large reservoir in China, was reinforced with plastic concrete cut-off walls between 13 January 2009 and 29 May 2010, as it was subject to leakage and deformation. However, the deformation development and the mechanism of the dam are still unclear. In this study, the deformation fields before and after the reinforcement of the Liuduzhai Dam were yielded by using the Interferometric Synthetic Aperture Radar (InSAR) technique. Furthermore, a numerical simulation method was employed to obtain the dynamic seepage field of the dam during the InSAR observation period. The results indicated that the average deformation velocity and maximum deformation velocity are −11.7 mm/yr and −22.5 mm/yr, respectively, and the cumulative displacement exceeds 100 mm, which shows typical continuous growth characteristics in a time series. In contrast, the dam deformation tended to be stable after reinforcement, with the average deformation velocity and maximum deformation velocity being −0.4 mm/yr and −1.2 mm/yr, respectively, behaving as cyclical deformation time series. According to the results of InSAR and seepage analysis, it is shown that: (1) dynamic seepage was the main mechanism controlling dam deformation prior to reinforcement; (2) the concentrated load caused by construction and the rapid dissipation of pore water pressure caused by the sudden drop of the infiltration line were the reasons for the acceleration of deformation during and after construction; and (3) the plastic concrete cut-off walls effectively reduced the dynamic seepage field, while the water level fluctuations were the main driving factor of elastic deformation of the dam after reinforcement. This study provides a novel approach to investigating the deformation mechanism of earth-rock dams. Furthermore, it has been confirmed that InSAR can identify the seepage deformation of dams by detecting surface movements. It is recommended that InSAR deformation monitoring should be incorporated into future dam safety programs to provide detailed deformation signals. By analyzing the temporal and spatial characteristics of the deformation signal, we can identify areas where dam performance has degraded. This crucial information aids in conducting a comprehensive dam safety assessment.

Machine learning based inversion for earth rock dam compaction density

In water resources and hydropower engineering and highway engineering, the compactness test of earth-rock mixed materials of the earth-rock dam and embankment plays an important role for construction quality assessment. The key is how to accurately and quickly evaluate the compaction density, which requires advanced methods. Meanwhile, machine learning has become an important and powerful tool for parameter prediction. In this work, a method to obtain the compactness of an earth-rock dam using machine learning algorithms is developed and verified. In so doing, first, by analyzing and processing the measured time history signal from a new fast Portable Falling Weight Deflectometer (PFWD), including time domain, frequency domain and mechanical impedance analyses, six optimized characteristic parameters are obtained to invert for the compactness, including the stiffness coefficient, the maximum time difference, the maximum amplitude ratio, the central frequency difference, the maximum stiffness impedance and the resonance frequency. Pearson coefficient was used to analyze the correlation among the six parameters and Gini index was used to analyze the influence degree of the parameters on the relative wet density. Then, the Decision Tree (DT) model, Random Forest (RF) model and Gradient Boosting Decision Tree (GBDT) model were used to predict the wet density and dry density of materials, respectively, and compared. PFWD was applied on a dam to acquire the time history signal, which was then preprocessed following a series of procedures including integrity check, outlier handling and normalization etc, and machine learning algorithms were used for training the data and parameter prediction. Examples show that, considering the generalization and optimization ability, for the GBDT model, the root-mean-square error (RMSE) of the predicted wet density of the earth-rock material is within 0.041 g/cm3 and that of the predicted dry density is within 0.032 g/cm3, which meet the requirements for construction detection and quality control. The proposed method based on PFWD signal analysis and machine learning algorithm models help better solve the nonlinear mapping problem between the PFWD signal and material density, and can accurately invert for the wet density and dry density of materials. It is an effective way for rapid detection and control of earth-rock dam construction quality.

Dynamic Parameters Updating of Earth-rock Dams Based on Modal Parameter Identification

The reasonable selection of dynamic parameters of earth-rock dams is very important for the seismic safety assessment of dams. Because of the size effects, the parameters acquired from the indoor test may additionally no longer exactly reflect the real dynamic characteristics of the dam. Therefore, it is essential to correct and update the dynamic parameters in accordance to the actual seismic dynamic characteristics of the dam. In this paper, by combining the Covariance-driven stochastic subspace identification (SSI-COV) method and the multiple population genetic algorithm (MPGA), an optimization and updating method for the dynamic parameters of earth-rock dams based on modal parameter identification is presented. The collected weak earthquake records of the dam allowed the modal parameters (the natural frequencies and mode shapes) identification based on SSI-COV method. The optimization updated is performed using the MPGA, which can obtain the optimal values of dynamic parameters of the dam and has good robustness within the optimization range of the numerical model. A typical numerical example is given to exhibit the feasibility and effectiveness of the presented method. Then the dynamic parameters of Liyutan Dam are updated by the proposed method according to the weak earthquake records, and the accuracy and applicability of the updated parameters were further verified by the strong earthquake records. The results show that the method proposed in this paper can provide a good idea for the calibration of dynamic parameters of earth-rock dams and has well practical engineering value.

Jaya-ICSM: A rapid inverse method driven by monitoring data for concrete-faced rockfill dams static displacement simulation

This paper presents a rapid static parameter inverse method for concrete-faced rockfill dams based on displacement data using an improved cloud surrogate model and the Jaya optimization algorithm. The improved cloud surrogate model (ICSM), which evolved from the uncertainty cloud theory, is used rapidly to establish a nonlinear relationship between static parameters and displacement. The Jaya optimization algorithm, which is proficient in recognizing the extreme value of the objective function, is selected for parameter identification. To verify the performance of the proposed method, an inverse analysis of two numerical models and a real engineering project is considered, and a comparative study with the BP neural network as the surrogate model is conducted. Study results demonstrate that ICSM has an extremely high prediction accuracy, with a mean relative error that is always under 1 %. The prediction accuracy does not increase too much even under complex nonlinear conditions or when dealing with sparse training data. Moreover, Jaya-ICSM maintains high computational efficiency throughout the entire inverse analysis, saving more than 98 % of the time compared to another inverse method and proving to be much better than direct inversion based on the finite element method. This enables real-time inverse analysis and state feedback of complex engineering. The results also illustrate that the Jaya-ICSM is promising in parameter recognition and superior in supporting the displacement evaluation of earth-rock dams. Therefore, the proposed method can be an effective tool for engineers to evaluate the safety of earth-rockfill dams and ensure their long-term stability.

Leakage channel outlet detection and diameter estimation for earth-rock dam using ROTDR

In the early stage of leakage in earth-rock dam, detection and quantification of the leakage channel outlet can provide an important reference for leakage hazard assessment and emergency response. In this paper, Raman Optical Time Domain Reflectometry (ROTDR) is used to detect the leakage point and a leakage channel outlet diameter estimation method is proposed. Firstly, the variation law between the sensing fiber of different length and ROTDR measurement results under the condition of different temperature difference is explored. Then, a model is constructed to simulate the leakage of earth-rock dam. The sensing fiber is deployed on the shallow layer of downstream slope and cushion of earth-rock dam to detect leakage. Finally, according to the measurement results, the leakage point is located and the diameter of leakage channel outlet is estimated. The estimated value is very close to the measured value. This study provides a useful reference for promoting the quantitative research of ROTDR in leakage detection.

An enhanced multiobjective bacterial foraging algorithm for the compaction parameter optimization of earth-rock dams

Compaction parameters can act as key decision variables. However, there is a lack of research on the optimization of compaction parameters considering quality, time, and costs. Existing algorithms have difficulty coping with this highly complex and nonlinear problem. To address this issue, an enhanced multiobjective bacterial foraging algorithm is proposed for searching the optimal compaction parameters of earth-rock dams. The cost and time are taken as multiple objectives, and the compaction quality is considered the main constraint because it must meet a certain standard. Then, the enhanced multiobjective bacteria foraging algorithm (EMOBFA) is proposed, which integrates multiple intelligent components into the fundamental single-objective bacterial foraging algorithm, including chaotic mapping, an adaptive step, a rotation learning strategy, and quantum computing. This further improves the speed and accuracy of the state-of-the-art multiobjective optimization algorithm. Finally, multiobjective test functions are used to compare the EMOBFA with commonly used multiobjective optimization algorithms to verify its generality, power, and scalability. A real-life large-scale water conservancy project in Southwest China shows that the proposed EMOBFA has realized the optimization of compaction parameters in the prior control of rolling construction.

Fast inversion method for seepage parameters of core earth-rock dam based on LHS-SSA-MKELM fusion surrogate model

The inversion of seepage parameters is an important research topic in the safety evaluation of earth-rock dams. Core earth-rock dam is a commonly used structural type in earth-rock dams. Most of the existing inversion methods focus on concrete dams, and few of them are aimed at earth-rock dams. These methods have the problems of slow inversion speed or low accuracy. Aiming at the above problems, this paper proposes a novel fast inversion method for the seepage parameters of core earth-rock dams based on the LHS-SSA-MKELM fusion surrogate model. The proposed fusion inversion model optimizes the selection of combination models based on the surrogate model framework, making it more suitable for the inversion calculation of seepage parameters in earth-rock dams. First, based on the seepage theory of earth-rock dams, the finite element numerical simulation model of core earth-rock dam seepage is constructed. The Latin Hypercube Sampling (LHS) method is used to obtain the parameter sample dataset according to the range of the seepage parameters, and the sample dataset is substituted into the finite element model to obtain the corresponding theoretical seepage pressure of different datasets. Then, the Mixed Kernel Extreme Learning Machine (MKELM) is used to establish the mapping relationship between seepage parameters and the theoretical seepage pressure. The MKELM parameters were optimized by using the Sparrow Search Algorithm (SSA) to further improve the accuracy of the surrogate model. Finally, taking the minimum error between the theoretical value and the measured value of the surrogate model as the objective function, the SSA algorithm is used to derive the optimal inversion value of seepage parameters. The results of engineering examples show that the mean absolute percentage error between the measured value of the core earth-rock dam seepage pressure and the simulated value after inversion is only 4.958%. In addition, the average inversion time of the proposed surrogate model is only 6.6 s, which greatly reduces the time-consuming problem of numerical simulation. The proposed method provides a new way for accurate and fast inversion of seepage parameters of core earth-rock dams after long-term operation.

Temperature tracing test and numerical simulation study during leakage of earth-rock dam

The leakage of earth rock dams exhibits characteristics of space-time randomness, concealment, and significant destructiveness. Prompt detection and identification of dam leakage are critical to ensuring the structural safety of these constructions. The distributed optical fiber temperature measurement method, which is based on optical frequency domain reflection (OFDR) technology, possesses attributes such as high spatial resolution, minimal temperature error, short response time, and real-time monitoring. As a result, it is an ideal technique for experimental research on leakage monitoring of earth rock dams. In this study, a model test was conducted on a clay core rockfill dam to investigate the feasibility of utilizing distributed optical fiber for identifying dam leakage. The variation pattern of partial distributed optical fiber temperature measurements in the dam body under the leakage state was compared and analyzed using the gradient method and the thermal pulse method. Furthermore, the heat flow coupled numerical simulation method was employed to verify and expand the findings of the indoor tests. The results of this study indicate that the OFDR distributed optical fiber leakage monitoring method using the thermal pulse approach can entirely reflect the temperature changes that occur during leakage, thereby providing strong reliability and exhibiting considerable potential for leakage location. The study offers valuable insights and a reference for the practical use of distributed optical fiber to monitor earth rock dam leakage.

A coupled FEM-DEM study on mechanical behaviors of granular soils considering particle breakage

Particle breakage often occurs in the fields of geological, geotechnical and hydraulic engineering like rock avalanche, landslides and high earth-rock dam, which affects the design and countermeasures of relevant engineering structures. Investigation of particle breakage’s effect on mechanical behaviors of granular soils has always been the hotspot within the community of particulate materials. In this study, a coupled finite element method (FEM) and discrete element method (DEM) modeling has been developed to tackle boundary value problems (BVPs) related with particle breakage. In the method, the particle breakage simulation is implemented in DEM through the conventional bonded particle modeling (BPM), while the stress–strain characteristics of representative volume element (RVE) captured by DEM is directly transmitted into the FEM solver to avoid the complicated and phenomenological constitutive equations incorporating into particle breakage. As an illustration, we apply the proposed multiscale modeling to investigating mechanical behaviors of quartz sands subjected to particle breakage through the high confining pressure biaxial compression simulation. And effects of particle strength, particle shape and confining pressure on particle breakage characteristics and further mechanical behaviors of quartz sands are also discussed accompanied with the underlying micromechanisms. Results demonstrate that the coupled FEM-DEM modeling can be able to deal with the complex geomechanics problems involving particle breakage.

Stability analysis of slopes based on cloud model-Monte Carlo coupling

Risk analysis of dam slopes is crucial for ensuring the safety and stability of hydraulic engineering. To improve the accuracy and reliability of risk analysis, we adopt the cloud theory approach and conduct a study on the distribution types of soil shear strength indicators based on indoor geotechnical tests. We propose a “cloud model-Monte Carlo” coupling model that uses the cloud model to describe the uncertainty of risk factors and determine the probability distribution types of shear strength parameters, while the Monte Carlo method is used to simulate random variables in the model. The effectiveness of the proposed model is validated through a risk analysis of a slope of an earth-rock dam, with results showing significantly greater accuracy and reliability compared to traditional methods. The calculation results show that the risk probability corresponding to the design flood level of the dam is 9.01×10-6, exceeding its allowable risk standard of 0.5×10-6, hence the need for reinforcement treatment. The proposed model can accurately evaluate the risk of dams and provide the scientific basis for decision-making in dam safety management.

Numerical investigation of seepage dissolution evolution of the bottom expansion cutoff wall in deep overburden

The bifurcation defect at the bottom of the cutoff wall in the deep overburden leads to a sharp increase in the local seepage gradient of the adjacent overburden at the bottom of the cutoff wall, which affects the evolution process of seepage dissolution of the cutoff wall. This study presents a novel type of bottom expansion cutoff wall to alleviate the problem that the seepage gradient of adjacent strata at the bottom of the cutoff wall far exceeds its allowed value. Considering the effects of the pore, aggregate, and convection on the calcium ion diffusion coefficient of concrete, we propose a coupling analytical model of seepage dissolution for two cutoff wall schemes, including the bifurcation defect schemes and bottom expansion schemes, to investigate the evolution of calcium ion concentration, porosity, and seepage characteristics, and to reveal the influence mechanism of the bottom bifurcation defect and bottom expansion of the cutoff wall on the seepage dissolution of the cutoff wall in deep overburden. The results indicate that subjected to the bottom bifurcation defect, the calcium ion concentration of the cutoff wall decreases faster, and the porosity increases faster with the increase of service life compared to the conventional cutoff wall when subjected to the bottom bifurcation defect. With a bifurcation height of 24 m at the bottom of the wall, the service life of the cutoff wall is reduced by 6.64%. In contrast, the novel type of bottom expansion cutoff wall is used to reveal that the concrete porosity increases slowly with the increase of the expansion radius over the same service life. The seepage gradient of the adjacent overburden at the bottom of the cutoff wall is significantly reduced. The service life of the cutoff wall is extended by 47.33% due to its 5 m bottom expansion radius. This study can provide a theoretical basis for the evolution of long-term service performance of the cutoff wall of an earth-rock dam on deep overburden.

Research on key technologies for intelligent and fine-grained construction of earth–rock dams based on artificial intelligence

Abstract High dam construction is continuing to develop with new requirements for intelligent dam construction. New information technology capabilities are providing paths for improved intelligent dam construction. This paper provides a comprehensive overview of the key technologies employed in the intelligent construction process of earth–rock dams. Starting with the multidimensional perception technologies and equipment utilized in earth–rock dam filling construction, it covers various aspects, such as the fine-grained management of unit construction based on building information modeling, rapid detection and qualification testing of dam materials’ physical characteristics, fast perception technology for material compaction, and unmanned driving technology for dam compaction equipment. Additionally, this paper highlights an overview of the existing technical challenges and future prospects in intelligent construction for earth–rock dams. These research results provide important references and lessons for the construction and development of high earth–rock dam engineering.

Using the Morgenstern–Price Method and Cloud Theory to Invert the Shear Strength Index of Tailings Dams and Reveal the Coupling Deformation and Failure Law under Extreme Rainfall

It is difficult to obtain reliable shear strength parameters for the stability analysis and evaluation of tailings dams in an unstable state. In this study, the sensitivity of the shear strength index to the safety factor of a tailings dam was evaluated. The cohesion C range of a tailings earth rock dam in an unstable state is determined by the safety factor, and the Morgenstern–Price method is used for inversion. During parameter inversion, uncertainty reasoning is established based on cloud theory, which overcomes the problem that the fuzziness and randomness of the quantitative cohesion value are transferred to the qualitative concept of the safety factor. The results show that the change in cohesion C has a greater influence on the safety factor Fs of the tailings dam, and the value of parameter inversion is 8.6901 kPa. The deformation and failure of tailings dams under extreme rainfall conditions are analyzed by using the modified cohesion C value. The dam toe becomes the main response area of plastic deformation and slowly expands to the interior, showing creep deformation. The displacement field gradually transfers from the accumulated tailings to the tailings dam with the flow direction, causing erosion damage. This study provides a new idea and method for parameter inversion of the shear strength index of tailings dams and provides a reference for the disaster prediction and prevention of tailings dams subjected to extreme rainfall.

Обзор методов прогноза гидравлического разрыва противофильтрационного ядра каменно-земляной плотины

Introduction. The phenomenon of hydraulic fracture is associated with the failure of some earth-rock dams, in which the integrity of the core made of clay soil has been compromised. It is believed that hydraulic fracture occurs when the pressure of water contained in pores and microcracks overcomes the compressive stresses in the soil. At this point, several methods have been proposed for the computational prediction of hydraulic fracture. They are aimed at determining the conditions under which hydraulic fracture occurs and at determining the critical water pressure that causes fracture growth. Materials and methods. A review of foreign scientific publications was carried out to systematise information on methods and techniques for critical pressure determination. Results. The review gives a classification of methods for predicting hydraulic fracture. Theoretical methods are based on the usage of elasticity theory, plasticity theory or fracture mechanics. The simplest method is based on the analysis of the stress state of the soil mass. This review describes methods based on the analysis of the stress-strain state of soil around a cavity with internal pressure. They consider several mechanisms of crack propagation, including the loss of tensile and shear strength. Empirical formulas based on the results of laboratory experiments are also given. In the framework of the analytical review, a comparison of some methodologies has been carried out. Most of the methodologies agree that the critical pressure primarily depends on the minimum principal stress σ3 in the ground. The comparison showed that the critical pressure calculated by the theoretical triaxial stress analysis technique is noticeably lower than that calculated by the empirical techniques. In the presence of a cavity, the more likely cause of fracturing is the loss of shear strength of the soil rather than tensile strength. Conclusions. Despite the abundance of techniques for predicting hydraulic fracturing, no theoretically verified and accurate methodology has been established at the present time.