Dam Slope Research Articles

Experimental Study of Erosion Prevention Model by Bio-Cement Sand

Microbially induced carbonate precipitation (MICP) technology is employed to reinforce the surface soil of a dam, aiming to prevent erosion caused by water flow and damage to the dam slope. The relationship between penetration depth, calcium carbonate content, and bonding depth was investigated at eight measuring points on the sand slope surface of a mold under different reinforcement durations. It was observed that as grouting reinforcement times increased, there was a gradual increase in calcium carbonate content but a rapid rise in penetration resistance. Moreover, the bonding depth of sand on the bio-reinforced sand slope increased with higher levels of calcium carbonate content. Microbial grouting reinforcement enhanced soil particle bonding force, requiring water flow to overcome this force for activation of sand particles. Consequently, microbial grouting reinforcement significantly improved shear strength and critical starting flow velocity on sand slope surfaces. The experimental results demonstrated that after MICP surface treatment through spraying, a dense and water-stable hard shell layer composed of bonded calcium carbonate and soil particles formed continuously on sample surfaces, effectively enhancing the strength and erosion resistance of sandy soils. These findings provide reliable evidence for silt slope reinforcement and dam erosion prevention.

Analysis on dynamic characteristics of dam material and seismic response of embankment dam in Longyang Reservoir

PurposeThe geological conditions of Longyang Reservoir are complex and it is located in strong earthquake area. In order to determine its seismic characteristics, the seismic response and residual deformation of embankment dam should be studied to provide calculation basis for dam design and construction.Design/methodology/approachBased on the geological survey data of Longyang Reservoir, the dam filling materials are tested by dynamic deformation tests, and the equivalent linear constitutive model parameters of the filling materials are obtained. Based on Duncan-Chang E-B model, the stress state of embankment dam in Longyang Reservoir before earthquake is calculated, and the dynamic response and earthquake residual deformation of embankment dam in Longyang Reservoir under earthquake condition are calculated by using equivalent linear model and Shen Zhu-jiang’s residual deformation model.FindingsThe results show that with the increase of dynamic shear strain, the dynamic shear modulus decreases and the damping ratio increases. The scatter plot between dynamic shear modulus and dynamic shear strain, and the scatter plot between damping ratio and dynamic shear strain under different confining pressures show strips. The calculation results shows that the acceleration of embankment dam in Longyang Reservoir increases with the increase of dam height, and the acceleration distribution has obvious amplification effect. Combined with the maximum dynamic shear strain during the earthquake and the state before the earthquake, the maximum vertical residual deformation of embankment dam in Longyang Reservoir is 2.98 cm which occurs at the top of the dam, calculated by the Shen Zhu-jiang’s residual deformation model.Originality/value Finite element calculation model parameters of embankment dam are obtained by dynamic triaxial tests. Seismic dynamic responses and residual deformation of embankment dam are analyzed. With the increase of dam height, the acceleration distribution shows an obvious amplification effect. The vertical displacement of embankment dam is larger along the dam axis and decreases in the upstream and downstream direction. The maximum horizontal displacement of embankment dam occurs in the middle of upstream and downstream dam slopes.Highlights(1)Finite element calculation model parameters of embankment dam are obtained by dynamic triaxial tests.(2)Seismic dynamic responses and residual deformation of embankment dam are analyzed.(3)With the increase of dam height, the acceleration distribution shows an obvious amplification effect.(4)The vertical displacement of embankment dam is larger along the dam axis and decreases in the upstream and downstream direction.(5)The maximum horizontal displacement of embankment dam occurs in the middle of upstream and downstream dam slopes.

Failure mechanism of loess landslide induced by water stagnation on the combined surface

In order to reveal the destructive mechanism of loess landslide induced by stagnant water on the combined surface, and to clarify the influence of the main control factors, this paper takes a typical loess landslide in northern Shaanxi as the research object, analyzes the structure of the rock and soil body, and the excavation and filling construction through the geohazard survey, and analyzes the process of traction sliding caused by the stagnant water on the combined surface at the different stages of the project by combining with the calculation of the stability of the slope body. Further the article analyses the process of traction sliding caused by water on the combined area due to construction by means of a discrete element model, and delves into the mechanism of strength reduction of saturated loess. The results show that: 1) the combined surface stagnant water type loess landslide has the characteristics of sudden sliding and rapid evolution, which is highly hazardous and difficult to prevent and control; 2) the slope destabilization is controlled by the engineering geological conditions, and the slope excavation changes the original mechanical equilibrium conditions of the slope, which provides the dynamic conditions for the traction sliding of the slope; 3) the change of the hydrogeological environment results in the obstruction of the natural drainage channel, which leads to the formation of continuous sliding surface due to stagnant water on the combined surface, and the formation of a continuous sliding surface due to stagnant water on the combined surface. Surface stagnant water to form a continuous slippery surface, inducing the overall destabilization of the slope damage; 4) loess strength index with the increase of saturation and the exponential function form of reduction, and when the saturation degree reaches more than 80%, the strength index of the soil body to reach the basic stability. The article expanding the ideas of landslide control and analysis, and the research results will provide a theoretical basis for the design of junction landslide management in the loess areas of northern Shaanxi.

The Drawdown of a Reservoir: Its Effect on Seepage Conditions and Stability of Earth Dams

This article addresses the reliability and safety of an earth dam in the case of a change in the reservoir water level. The water level must often be reduced to remove water or as a response to an emergency situation in the process of operation of a hydraulic structure. Lower water levels change seepage conditions, such as the surface of depression, values and directions of seepage gradients, seepage rates, and volumetric hydrodynamic loading. Practical hydraulic engineering shows that these changes can have a number of negative consequences. Higher seepage gradients can lead to seepage-triggered deformations in the vicinity of the upstream slope of a structure. Hydrodynamic loads, arising during drawdown, reduce the stability of an upstream slope of a dam and cause its failure. Potential consequences of a drawdown can be evaluated by solving the problem of drawdown seepage for the dam body and base. A numerical solution to this problem is based on the finite element method applied using the PLAXIS 2D software package. Results thus obtained are compared with those obtained using the finite element method in the locally variational formulation. A numerical experiment was conducted to analyze factors affecting the value of the maximum seepage gradient and stability of the earth dam slope. Recommendations were formulated to limit the drawdown parameters and to ensure the safe operation of a structure.

Transient Electromagnetic Field Response Analysis Considering Dam Boundary Conditions

Abstract The transient electromagnetic (TEM) method has outstanding advantages in detecting depth and response information and can be used to detect anomalies hidden deep inside dams. However, the current data analysis method based on geological exploration is inapplicable to the interpretation of dam detection data, the main reason being the lack of consideration of the influence of dam boundary conditions on the diffusion of the TEM field. In this work, by establishing a numerical model of a dam for TEM detection, the effects of the dam slope ratio, upstream water body, overburden, and other dam boundary conditions on the TEM field were studied. The results showed that the slope ratio made the propagating TEM field to exhibit a constraining behavior, and a negative deviation could be seen in the attenuation curve, indicating a false high-resistance anomaly. The upstream water body distorted the diffusion of the electromagnetic field, and the low-resistance covering layer caused a low-retardation retention phenomenon in the magnetic field, leading to a positive deviation in the attenuation curve, indicating a false low-resistance anomaly. The influence of the boundary conditions was present throughout the entire observation window in which the detection was performed, and the sensitivity of the magnetic field to these boundary conditions was significantly higher than that of the change rate of the magnetic field. With the increase in the observation time, the main influencing factors were the slope ratio, overburden layer, and upstream water body.

Dynamic reliability and seismic fragility analysis for high concrete-faced rockfill dam slopes subjected to stochastic earthquake and parameter excitation via PDEM

The randomness of material parameters and earthquake excitation greatly impacts the seismic stability of high concrete-faced rockfill dam (CFRD) slopes. However, no research has comprehensively analyzed the impacts of stochastic earthquake excitations, random parameters and their coupled effects on seismic stability of CFRD slopes and selected a multi-indicator evaluation criterion to carry out performance-based safety assessment. This paper develops a novel and comprehensive framework for evaluating the seismic stability of CFRD slopes based on the generalized probability density evolution method (GPDEM) with high efficiency and accuracy. The effects of three kinds of randomness on seismic stability of CFRD slopes were comprehensively compared and analyzed on the basis of multi-indices (safety factor (FS), cumulative slip displacement and cumulative time with FS < 1.0). Firstly, the nonlinear shear strength parameters of 40 high CFRDs were statistically collected to obtain the statistical characteristics of rockfill material strength parameters of actual CFRD projects. Secondly, three kinds of random samples were generated using generalized F-discrepancy (GF-discrepancy) method and Spectral expression-Random function (SERF) method. Then, the GPDEM was introduced to combine with three indices to perform the stochastic analysis and reliability evaluation. Finally, the fragility analysis of the CFRD slope was conducted. The results reveal that FS is more sensitive to the ground motions randomness, while cumulative slip displacement and cumulative time with FS < 1.0 are more sensitive to the material parameters randomness. The seismic safety evaluation of CFRD slopes based on multiple indices with full consideration of coupled randomness effects is necessary.

Analysis of the impact of dam slope modifications on the sensitivity to rapid drawdown, earthquakes, and changes in water level at the Jragung Dam in Semarang Regency

Analysis of the impact of dam slope modifications on the sensitivity to rapid drawdown, earthquakes, and changes in water level at the Jragung Dam in Semarang Regency

Code 1583 - preliminary steps for studies to assess the safety of an earth dam in terms of use and lowering the reservoir level for public supply during the water crisis

The spring 2021 climate forecast report from the National Institute of Meteorology (INMET) and the National Institute for Space Research (INPE) indicated an increased possibility of below-average rainfall in almost the entire region of the state of Paraná, which is consistent with the historical trend of decreasing rainfall in the Paraná River basin since the 1990s, with an intensification in the 2000s. This led to a water emergency situation in Paraná, which was decreed by the state government in 2020 and 2021. The Curitiba region depends on the Curitiba and Metropolitan Region Integrated Supply System (SAIC). Due to the intense drought in 2020 and 2021, SAIC's reservoirs suffered a significant reduction in stored water levels and volumes, reaching 28% of their total capacity in August 2020. This was the biggest water crisis in the last 90 years in the history of the state of Paraná, with several reservoirs reaching levels close to historic lows, but maintaining constant discharges in order to maintain power generation or public supply. In these cases, with the reservoirs at lower levels and with a smaller volume, the variation in the water level on the upstream slope of the earth dam varies differently from the levels when the dam and reservoir are in normal operation or outside of a water crisis. In view of the atypical behavior of reservoir levels, and based on good dam engineering practice, when the operating regime changes or the reservoir water level drops, the safety aspects of these structures should be reassessed through geotechnical analyses for conditions of rapid lowering, in order to learn how these structures behave under these conditions. This article sheds light on the important stages of this thorough technical investigation of the extensive documentation of a project like this, data on instrumentation and performance, how they were built and behaved during the construction and filling of the reservoir, knowledge of geotechnical parameters of the materials of the dam massif and foundation, recorded field observations made at the time of preliminary investigation during the design, project and construction phase; obtaining hydro-meteorological data from the region, in order to obtain the "as-built" geometry of the structure, with the aim of modeling the typical section reliably to the structure in the field in order to infer this numerical model and vice versa, and obtain results on its performance during this atypical period.

Original Insights Into Rock Slope Damage Processes Until Collapse From Passive Seismic Monitoring

AbstractWe performed a passive seismic monitoring of the La Praz ∼14,000 m3 unstable slope (French Alps) spanning over 10 years. During the last 6 months prior to collapse, we detected a clear 24% decrease in the slope's fundamental resonance frequency, f0, caused by a reduction in overall rock mass stiffness. The combined study of f0 and slope deformation suggested the alternating importance of sudden brittle failure processes versus more ductile phases with possible sliding. Seismic monitoring revealed slope damage that remained ambiguous or undetected with ground surface deformation monitoring, and highlighted critical periods with intense damage. Only some of these critical damage periods could be related to clear external forcing factors such as intense rainfall episodes. These new insights into rock slope's structural condition at depth represent an asset for future monitoring systems. Surface deformation and passive seismic stiffness tracking combined could reveal active slopes with ongoing damage processes.

Mapping rockfall hazard and detecting precursory damage in rock slopes with passive seismic: Lessons from the La Praz case-study

We conducted repeated successive passive seismic surveys on the La Praz unstable rock slope (∼13,000–15,000 m3, Savoie, France), spanning over more than ten years. The last survey was conducted two months before its complete collapse in August 2023. We used the amplitude of Horizontal to Vertical Spectral Ratio at peak (aHVSR(fp)) to discriminate stable from unstable areas and delineate the fractures with major mechanical decoupling effect. We also classified the compartments in terms of rockfall hazard: the most prone-to-fall areas showed the highest aHVSR(fp) (in the range [26–157]), compared to [7.5–19] on intermediate areas and 2.7 on adjacent stable rock mass.The frequency of HVSR main peak (fp) on three unstable rock compartments showed unambiguous −15%, −14% and −11% drops prior to the collapse. These drops significantly exceed the range of environmentally driven resonance frequency wandering observed on site and generally reported as a limitation in the literature. These drops were interpreted as progressive in-depth slope damage. Interestingly, fp losses were detected solely on the three most prone-to-fall rock compartments showing the highest aHVSR(fp). The unveiling of in-depth damage processes on such a complex, heterogenous and highly fractured rock slope using passive seismic is a first.

Enhancing earth dam slope stability prediction with integrated AI and statistical models

This study introduces an innovative approach integrating artificial intelligence (AI) and statistical modelling techniques to enhance the prediction of earth dam slope stability. Utilizing advanced methodologies, including Classification and Regression Tree (CART), Classification and Regression Random Forests (CRRF), and Multiple Linear Regression (MLR), this research provides a comprehensive, data-driven analysis for slope stability prediction. The integration of AI with traditional statistical models significantly improves the predictive accuracy over conventional methods. The findings reveal the model's capability in terms of reliability and precision in predicting slope stability, demonstrating its potential as a powerful tool in geo-engineering. Additionally, this work highlights the effective application of AI in complex geo-environmental systems analysis, opening new avenues for research and practice in the field.

Seepage and Stability Analysis of Earth Dams’ Downstream Slopes, Considering Hysteresis in Soil–Water Characteristic Curves under Reservoir Water Level Fluctuations

Fluctuations in reservoir water levels have a significant impact on the seepage and slope stability of earth dams. The varying rate of the water level and soil–water characteristic curve (SWCC) hysteresis are the main factors affecting the seepage and the stability of dam slopes; however, they are not adequately considered in engineering practices. In this study, the SEEP/W module and the SLOPE/W module of Geo-studio were employed to analyze the seepage features and the stability of downstream slopes, taking into account the water level fluctuation rate and the SWCC hysteresis. The results reveal that the pore water pressure of the representative point forms a hysteresis loop when the water level fluctuates, which becomes smaller as the water level variation rate increases. Within the loop, the pore water pressure with a rising water level is greater than the value when the water level is dropping, and the desorption SWCC derives greater pore water pressures than the adsorption SWCC. Similarly, the safety factor (Fs) curves under the condition of water level fluctuations also form a hysteresis loop, which becomes smaller as the variation rate of the water level increases. When the water level fluctuation rate increases to 4 m/d, the two curves are tangent, meaning that the Fs with a rising water level is always greater than the value when the water level is dropping. The desorption SWCC derives a lower Fs value than the adsorption SWCC as the water level draws up, but this initiates no evident difference in the Fs value when the water level draws down. These findings can be used to inform the design and operation of earth dams under fluctuating water levels.

Impact of Deforestation and Erosion on Some Soil Physicochemical Properties and Microbial Activity on Steep Slopes

Deforestation and erosion are important indicators of the beginning of land degradation. This study aimed to present the changes in some physical, chemical, and microbial characteristics of the soil on sloping land on which deforestation has led to gully erosion. The study was conducted on dam slopes on which the forest cover had been removed, and gullies subsequently formed. Nine soil samples were taken from deforested and eroded slopes (SDE) and six soil samples were taken from slopes with forest vegetation (SF) for physical and chemical soil analysis. Thus, a total of 15 samples were taken from the study area to determine physical and chemical properties. To determine microbial biomass and activity, a total of 30 samples were taken from the same locations in duplicate. The results revealed that sand particles, bulk density, soil temperature, &amp;gt;2 mm/&amp;lt;2 mm fraction ratio, pH, and electrical conductivity increased markedly, whereas total porosity and organic carbon decreased (p≤0.05) in SDE soils. Moreover, it was found that the average organic carbon content of SDE soils decreased by more than five times compared to SF soils. Microbial biomass carbon and basal respiration in SDE and SF soils indicated a significant difference (p≤0.05). While the metabolic quotient indicated a marked difference (p≤0.05) between SDE and SF soils, the microbial quotient showed no significance (p&amp;gt;0.05). Furthermore, it was found that the most relevant physical and chemical soil characteristics of microbial biomass and activity were bulk density, pH, and organic carbon.

Liquefaction-induced large deformation method with automatic time-step mapping and interfacial interpolation improvement: Case study of the San Fernando dam

This study constructed the u-p equation for saturated soil in the meshfree global weak form within the arbitrary Lagrangian-Eulerian (ALE) framework to solve the problem of liquefaction-induced large deformation induced by strong seismic loading. The interpolation improvement in the near-interface zone was achieved using domain truncation optimization and the local nodal refinement algorithm, and the relative error of the shape function was proposed as the judgment criterion for radial basis function (RBF) field variable mapping. Finally, a high precision meshfree liquefaction-induced large deformation method (MFLLDM) with automatic time step mapping and interfacial zone interpolation improvement was established. The MFLLDM achieved the efficient dynamic updating of soil stress state and pore pressure information in space during the deformation process and more accurately depicted the localized large shear deformation characteristics of the soil in the near-interface zone. The proposed method was integrated into a custom-built large-scale finite element method (FEM) computing system (GEODYNA), based on object-oriented and super element program design technology. This enabled the efficient coupled analysis of MFLLDM in the liquefied-induced large deformation zone and FEM in the small deformation zone. Numerical consolidation examples were used to validate the accuracy, convergence, and applicability of the soil elasto-plastic model for MFLLDM. The method was then used to simulate the liquefaction damage of the San Fernando dam, which reproduced the development process of large slip deformation and high-water pressure ratio for the upstream dam slope.

Numerical simulation of frost heaving damage of earth-rock dam berms in cold regions with thermo-hydro-mechanical coupling

In order to investigate the freezing damage problem of berms of earth-rock dams in cold regions, an earth-rock dam in a cold region was selected as the research object in this study. A finite element model, considering the effect of thermo-hydro-mechanical coupling, has been developed to solve the problem by combining the characteristics of the earth-rock dam. The whole process of freezing damage of berms under the influence of the reservoir level and the water migration of the dam filling was investigated, and the laws in temperature, humidity and displacement of earth-rock dams were analyzed. The calculated displacement field was then compared with the measured frozen deformation data to validate the results of the finite element simulation. The results showed that the freezing influence range of the dam slope was about 2 m, the range of temperature influence on the dam slope mainly depended on the depth of freezing, and the temperature change in the shallow range (0–2 m) of the dam slope was influenced by the outside air temperature. Also, the internal temperature of the dam body was small relative to the shallow dam slope, and there was a certain hysteresis. In addition, the effect of negative temperature was such that the shallow pore water phase of the dam slope turned into ice, manifesting macroscopically as a reduction in unfrozen water content. Water phase change, water migration from the dam filling to the dam slope, and the movement of the ice peak towards the dam body were found to be the main causes of berm freezing and expansion damage. The calculated amount expansion (due to freezing) of the dam slope was found to be in the range of 20–30 cm with a maximum value of 36 cm, which was consistent with the measured results. It was also found that the freezing and expansion damage of the berm is mainly caused by the joint action of freezing and expansion of the soil and rock mixture such as gravel bedding and dam filling, as well as the ice thrust force. It is expected that the results of this research can provide a basis for the design of berms of earth-rock dams in cold regions.

Risk Assessment of Mamak Dam Based on The ICOLD Modification Method and Risk Index Method

The Mamak Dam has the risk of damage and the need for evacuation at an extreme downstream level. Risk considerations are based on the potential natural disasters of the dam, the impact of dam failure, design loads, and safety coefficients. The Risk Index method results in a score with parameters such as spillway capacity adequacy, safety factor adequacy against slopes, disaster factor (hazard), and all parameters analyzed to determine the Dam Safety Index (Idam). The drawback of the Risk Index method is neglecting downstream failure analysis. The ICOLD modification method for parameters is the same as the Risk Index method, but the ICOLD method considers downstream analysis. The modification involves adding parameters, such as the condition of the dam slope cover layer, based on the Mamak Dam Large Inspection results. In the Risk Index method, the Idam calculation value is 262.5. The total risk index value for Mamak Dam is 51.73, with a dam safety value of 92.337. In the ICOLD method, the Idam calculation value is 245, with a total risk index value for Mamak Dam of 48.28 and a Dam Safety value of 92.848. Meanwhile, using the Modified ICOLD method, the Idam calculation value is 245, with a total risk index value for Mamak Dam of 49.93 and a Dam Safety value of 92.603. Based on these results, the Dam Safety value with the Modified ICOLD method has decreased but still falls within the satisfactory classification (&gt;75). Therefore, it can be concluded that Mamak Dam is currently at a safe level against normal loads and extraordinary loads (design floods and design earthquakes).

Research on the slip deformation characteristics and improvement measures of concrete-faced rockfill dams on dam foundations with large dip angles

The pumped storage power station (PSPS) is an important measure to achieve the strategic goal of “dual carbon”. As one of the preferred types for the upper reservoir dams of PSPSs, the concrete-faced rockfill dam (CFRD) often has a dam foundation on a steep transverse slop and is prone to produce slip deformation along the slope, resulting in poor anti-sliding stability of the dam slope. It is dangerous for the operation safety of PSPSs. Therefore, the slip deformation of CFRDs on dam foundations with large dip angles is investigated. The mechanism for the initiation of slip deformation is revealed. The design measures of physical mechanic and geometric structure are proposed to reduce slip deformation. The results show that the larger sliding forces and smaller anti-sliding forces are the fundamental reasons that CFRDs on dam foundations with large dip angles are prone to produce slip deformation. The larger the dip angle of the dam foundation, the larger the slip deformation of the dam body and face slab, and the smaller the safety factor of the dam slope. When the dip angle of the dam foundation is greater than 15°, the safety factor of the dam slope is less than the minimum value of 1.5 required by codes. The addition of pressure slopes can effectively reduce the slip deformation of the dam body or face slab and significantly improve the anti-sliding stability of the dam slope. When the height or width of the pressure slope platform is greater and the cohesion or internal friction angle of the pressure slope is larger, the slip deformations of the dam body and face slab are smaller, and the safety factor of the dam slope is greater. It is recommended that the height and width of the pressure slope platform be 1/2 times the maximum height of the main dam, and the density (cohesion and internal friction angle) of the pressure slope be equivalent to that of the main dam’s rockfill material. The research results can provide theoretical and technical support for the design and construction of CFRDs for the upper reservoir of PSPSs.

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.

Evaluation of Slope Stability on Dam Using Ground-based Interferometric Radar

Dams are man-made structures built to manage water resources efficiently and prepare for natural disasters such as droughts and floods. It requires careful and continuous inspection to prevent its failure. Research reported to assess dam stability using terrestrial surveys such as ground penetration radar, electrical resistivity tomography, and remote sensing methods such as space-borne synthetic aperture radar (SAR). Differential interferometric SAR (DInSAR) calculates the phase difference between two consecutive images acquired at separate times and has been widely utilized to detect surface displacement from volcanoes, earthquakes, and ground subsidence. However, space-borne InSAR applications have limitations in acquiring flexible data for specific dates or regions due to the revisit cycle of the orbital configuration and the fixed acquisition geometry. In this feasibility study, the slope stability of the dam was evaluated using the Gamma Portable Radar Interferometer-II (GPRI-II) which has the advantage of overcoming the limitation of satellite observations. The GPRI-II is a ground-based real aperture radar that operates in the Ku-band wavelength (~1.7 cm), providing convenient portability and installation for high spatial and temporal resolution. A total of 20 GPRI-II datasets were acquired for 22 minutes on June 7, 2023, at a dam in Jeollanam-do for the DInSAR application. The displacement calculation revealed an average displacement of approximately -0.36 mm at a randomly selected point, which is negligible. The average displacement of -0.17 mm was observed for the entire dam. Our results suggest that ground-based radar interferometry could assess the dam slope stability.

Seismic safety assessment of dam slopes considering rockfill softening characteristics, shear strength uncertainties, and stochastic ground motion

The stability of the dam slope is one of the crucial indicators for maintaining the overall stability and reliability of the dam. The seismic stability response analysis of the dam slope involves a significant number of factors that introduce uncertainty, primarily including the stochastic ground motion and the uncertainty of the shear strength parameters of rockfill. Furthermore, the rockfill material is susceptible to strain-softening behavior at low confining pressures when subjected to ground motion, which exacerbates its progressive failure. Therefore, the assessment of seismic safety for dam slopes should give due consideration to this characteristic of rockfill material. This study extensively explores the influence of rockfill softening, stochastic ground motion, and the variability of rockfill shear strength parameters on the stability of the dam slope. Conducting probabilistic analysis in conjunction with the generalized probability density evolution method (GPDEM), the findings suggest that it is imperative to evaluate the safety characteristics of the dam slope by considering the coupled effects of stochastic ground motion, the variability of shear strength parameters, and the effect of rockfill material softening. Based on this, a preliminary dam slope failure classification was proposed, and a framework for dam slope seismic safety assessment was established.