Dam Slope Stability Research Articles

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.

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.

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.

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.

Reliability Analysis of the Slope Stability of Homogeneous Earth Dam under Seismic Loading

Earth dams are widespread throughout the world and their safety is the overriding concern of civil engineers, especially in regions with high seismic activity. This contribution presents a deterministic and reliability-based approach of the slope stability analysis of homogeneous earth dam under seismic loading. The hydrostatic loading as well as the saturation line in the dam body is considered for different design situations to investigate the effects of water level fluctuations on earth dam slope stability. Seismic loading is introduced by horizontal and vertical pseudo-static forces, while the considered failure mode is circular slip, analyzed with the classical method of slices. Given the nature of the soils, uncertainties about their properties must be considered in the assessment of the slope stability. These uncertainties can be quantified by a reliability analysis. The proposed reliability method is approached by the failure probability assessment of the slope stability of an earth dam based on Monte-Carlo simulation. The used random variables are the mechanical shear properties of the embankment body as well as the acceleration coefficient of the seismic zone. For the failure probability evaluation, the log-normal distribution law was used to generate the random variables. A computer program was developed using Matlab®. The developed approach was applied, for a practical example, to analyze the slope stability of an earthen dam located in Médéa (Algeria), whose dimensions are realistic. The results obtained with the developed analytical model were compared with those obtained with the Flac2D© software. The confrontation turned out to be satisfying.

Dynamic evaluation method for Time-variant reliability of structural safety of Concrete-faced rockfill dam

The evaluation of the structural safety risk for concrete-faced rockfill dams (CFRDs) is susceptible to the time-varying parameters and the environments of topography, geology, and operations. Traditional evaluation methods, due to their involvement in numerical simulation, cannot meet the current requirements for intelligent monitoring in terms of timeliness and practicality. Therefore, a dynamic evaluation method of reliability in CFRDs is proposed in this paper. Due to the nonlinear mapping relationship between the time-variant reliability and the monitoring characterizations of CFRDs, the long and short-term memory neural network (LSTM) and support vector machine (SVM) models are introduced to construct the potential functional relationships between the reliability sequences and the monitoring characterizations, and the matching between the accuracy of the two models and the frequency of monitoring characterizations has been fully studied, forming an adaptive evaluation model of safety risk for the CFRDs according to the different monitoring frequencies of different monitoring items. The application of Sanbanxi CFRD shows an average relative error of less than 1% and 5% for dam slope stability and slab cracking simulations, respectively. These results demonstrate that the LSTM and SVM models with adaptive monitoring frequency exhibit high fitting and prediction accuracy and applicability, and possess theoretical and engineering application value.

Reliability analysis of an embankment dam slope based on an ellipsoid model and PSO-ELM

Accurately comprehending the intricate characteristics of geotechnical parameters can be challenging due to the complexity of geotechnical engineering and the lack of available information. The accuracy and efficiency of conventional reliability analysis methodologies are impeded by the copiousness of raw data. This study proposed a non-probabilistic method for reliability analysis, which employed an ellipsoidal model integrated with a machine learning algorithm. This novel method characterized parameter uncertainties by their boundaries, utilized the synergy between particle swarm optimization and extreme learning machine for performance function surrogate, and employed an ellipsoidal model to calculate the reliability index. The proposed method was applied to evaluate the stability of an embankment dam slope in France. The results revealed the significant influence of the alterations in internal friction and cohesion on the stability of the embankment dam slope. Therefore, it can be imperative to account for the variability and correlation of soil parameters when conducting a rigorous analysis of embankment dam slope stability. Notably, the proposed method can circumvent the requirement for employing probability distribution forms to represent parameters, while concurrently ensuring a commendable level of computational efficiency and accuracy. Furthermore, the proposed method can be compatible with probabilistic analysis methods in evaluating the stability of the embankment dam, thereby providing an effective method for conducting reliability analyses of such structures.

Environmental and operational safety of tailing storage facilities: analysis of accidents, causes and technical state diagnostic methods

A number of high-profile industrial accidents occurred at sludge and tailings storage facilities in different countries of the world are considered. The problem of ecological and technogenic danger of operating such objects, which leads to significant casualties among the civilian population, serious economic losses and harms the surrounding natural environment, is illustrated. The main causes of emergency situations have been established and analysed, it will help to reduce the risk of accidents and to minimize negative environmental consequences for similar facilities in Ukraine. The retrospective review covers the period from 1960 to 2022. During this time, about 150 cases of soil dams’ destruction in waste storage facilities were recorded. The different tendency in the frequency of accidents is noted. In particular, during the period from 1960 to 2009, there were 98 accidents with an average frequency of nearly two (1.98) per year. Over the last decade (2010-2020), the number of accidents reached 36 cases, and their frequency almost doubled to 3.6 accidents per year. Over the past two years, from the beginning of 2021 to December 2022, 10 accidents have already been registered. The vast majority of accidents during this period occurred in 34 countries of the world. The largest number of them was noted in the USA (22.4%), China (10.4%), Brazil (7.5%), Chile (6.7%), the Philippines (6.0%), Canada (5.2 %), Great Britain (4.5%) and other countries. Studies note jumps in the increase of accidents that have ten-year trends (1975, 1985, 1995, 2005). The general tendency of mass accidents since the beginning of 2015 is shown, which is substantiated by the expired terms of operation of many mining and ore enterprises (mines) and significant (exceeding normative) terms of operation of tailings storage facilities, which in some places were left without proper supervision and care. It was established that a violation of the dam slope stability (37%), an overflow of the designed capacity of the tailings storage facility (12%), seismic activity (11%), etc., are the main causes of accidents. A review of modern approaches to the management of dangerous anthropogenic objects and methods of diagnosing the technical condition of such structures was conducted. The use of a complex of organizational and technical solutions about the implementing the modern methods of assessment and control the technical condition of waste storage facilities at various levels of their operation and stages of the life cycle is proposed.

Global Sensitivity Analysis Method for Embankment Dam Slope Stability Considering Seepage–Stress Coupling under Changing Reservoir Water Levels

Ensuring the long-term, efficient, and safe operation of reservoir dams relies on the slope stability of embankment dams. Periodic fluctuations of the reservoir water level due to reservoir scheduling operations make the slope of the reservoir bank vulnerable to instability. To investigate the influence of various factors and their interactions with embankment dam slope stability under changing reservoir water levels, a global sensitivity analysis method is proposed that accounts for seepage–stress coupling. An embankment dam in Shaanxi Province, China, is studied as an example, with COMSOL Multiphysics software simulating the seepage and slope stability of the dam under fluctuating reservoir water level conditions and seepage–stress coupling. The global sensitivity analysis of factors affecting dam slope stability is accomplished by combining Plackett–Burman and Box–Behnken experimental designs, with ANOVA determining the sensitivity of each factor and interaction term. The results demonstrate that during the impoundment period of the reservoir, the saturation line is concave, and the overall stability safety of the dam slope increases first and then tends to be stable, according to the coefficient. The internal friction angle φ, cohesion c, and soil density ρs represent the three most sensitive factors affecting the stability and safety of the dam slope, while c × ρs is a second-order interaction term with significant sensitivity to the stability and safety coefficient of the dam slope. The reservoir drainage period infiltration line is convex, and dam slope stability first reduced and then increased. The magnitude of water level change H, internal friction angle φ, cohesion c, and soil density ρs are the four most sensitive factors for the coefficient of safety of dam slope stability, while c × ρs, H × ρs, and φ × ρs are the second-order interaction terms with significant sensitivity to the coefficient of safety of dam slope stability. These research findings and methods can offer valuable technical support and reference for the investigation and evaluation of the stability of embankment dam slopes.

Effect of Core Geometry on Earth Dam Slope Stability

Embankment dams are widely constructed due to their suitability with different types of foundation, and it is constructed from the available material at the site. A zoned earth dam consists of a clay core at the center to control seepage supported by a shell. This paper investigated the impacts of side slopes, top width, and shape on upstream and downstream slope stability during different cases. Slide 6.0 software was used to evaluate the factor of safety of side slopes of an earth dam, and its result was validated. Different side slopes range from 0H:1V to 2 H:1V, and crest widths from 3m to 10 m were examined. In addition, for the slanting core case, several cases with varying angles of inclination were provided. The results indicated that by increasing the side slopes of the core, the factor of safety was reduced, especially in the steady state and rapid drawdown conditions. Increasing the top width also reduced the safety factor in the steady state condition. This reduction was because the core material had lower shear strength than the shell material. In addition, in a steady state and rapid drawdown conditions, the cohesion of core material sharply reduced. Compared with the vertical case, increasing the slanting core slopes influenced the slope stability insignificantly during the steady state. The slanting core had benefits in the steady state when the reservoir was full since, in this case, increasing core side slopes affected the slope stability insignificantly. The maximum core side slope in the earth dam and maximum top width, which insignificantly affected the dam’s slope stability, were 0.8:1 and 5 m, respectively.

Design method of polymer cut-off wall density for earth dams based on multi-objective optimization

Polymer grouting cut-off reinforcement technology is a highly efficient, minimally invasive, and cost-effective solution that is widely used in earth dam reinforcement projects. However, the density of polymer materials used in these projects is typically determined based on engineering experience rather than an optimal design method that considers factors such as deformation coordination, strength reserve, and economy. To address this issue, a multi-objective optimization-based design method for the density of polymer cut-off walls has been developed. The method takes into account several factors, including the maximum variable displacement difference and the maximum horizontal gap length between the cut-off wall and the dam soil (deformation coordination index), the maximum Mises stress of the cut-off wall and the dam slope stability factor (strength index), and construction cost (economic index). Each index is normalized, and an index weight is introduced to linearly combine the normalized values. The resulting function is then used to optimize the density of the polymer cut-off wall. For an actual engineering project, the optimized polymer densities were found to be 0.232 g/cm3, 0.223 g/cm3, and 0.29 g/cm3, with different index weights. This method provides valuable guidance for the design of polymer cut-off wall density in earth and dam reinforcement projects.

Stability of dam slopes taking into account anisotropy

This paper presents the results of experimental studies on the deformation and strength anisotropy of gravel-pebble soils used in soil dams. During stabilometric tests, varying shear angles were obtained for stone at different orientations of soil particles in the working chamber, whether horizontal or vertical. As the hydrostatic pressure in the working chamber increased to 0.8 MPa, a reduction of shear angles of a stone by 8-12 degrees depending on the direction of layering of soil was observed. The authors compiled a calculation program called OTKOS_Ani (Delphi), which considers the strength anisotropy of pebble soils for calculating the stability of slopes of soil dams and slopes. The slope calculations were carried out for different design and height of stone and stone-soil dams, and correction factors for taking into account the strength anisotropy in slope stability calculations, kан, were obtained depending on the type, height, and density of gravel-pebble soil stacking in the dam body. The results showed that considering the anisotropy of strength properties in the calculations of slope stability of earth dams reduces the safety factors by 3-11%. This should be taken into account when selecting the design of earth dams with prisms of gravel-pebble soils.

Theoretical Analysis and Development of an Artificial Neural Network Model to Evaluate Earthen Dam Slope Stability

In the design of earth dams, it must be considered that the water leakage through the earth dam generates upward and pore pressure, in addition to leakage forces that cause internal erosion, which has a direct influence on the structural stability of this system. Also, the rising and dropping in the water level has a direct effect on the stability of the dam's face slope. One way to solve these issues is the installation of a core or a horizontal water drainage system. The present study relied on the GEO-Studio computer tool to evaluate cross-sectional models of earthen dams by determining the safety factor under different situations represented by a change in filter type, and the flow state as a result of raising and lowering the water level at the dam reservoir and the full fill condition of the dam reservoir. The research found that the existence of a core substantially contributed to improving the safety coefficient for the case of rising the water level (2m) and rapidly rising by assigning it the greatest safety coefficient values. The absence of a filter had an opposite influence on the safety coefficient by decreasing it. Also, the factor of safety for the downstream slope was affected by less than 5% for different flow conditions, compared with the higher effect generated by the upstream slope. Furthermore, an artificial neural network model with an accuracy ratio of more than 97% was developed for the predicted safety factor.

TINJAUAN GEOTEKNIK KEAMANAN REMBESAN DAN PEMBEBANAN GEMPA PADA STABILITAS LERENG (Studi: Bendungan Way Sekampung)

Abstract : Way Sekampung Dam is built to optimize the utilization of the Way Sekampung watershed. It is classified as an embankment dam with upright core which is following with a high risk of failure. The research of dam slope stability become an effort to fulfill dam safety. This study is based on the effects of seepage and seismicity. The seepage review is focused on what is the safety of the dam against potential piping, while for seismicity it is carried out under earthquake loading which using a modified earthquake coefficient approach. Based on the calculation of the seepage modeling using SEEP/W at the flood water level (FWL) and normal water level (NWL) obtained a value of the calculated safety factor (SFcal) of ≥ SFmin = 4 and, it can be said to be safe against piping. Slope stability modeling with SLOPE/W at post construction, flood water level (FWL),normal water level (NWL), and low water level (LWL), under earthquake loading conditions, it is found that the calculated safety factor (SFcal) varies in each loading condition. In the OBE loading conditions; the calculated safety factor value (SFcal) is greater than SFmin, indicating that the slope stability at the Way Sekampung Dam is safe. The simulation with MDE loading conditions, show results of the dam slope stability modeling in several variation resulted in SFcal &lt; SFmin. This shows that the slope stability at the Way Sekampung Dam is not safe, have the potential to experience damage and collapse. Keywords: embankment dam, slope stability, seepage, earthquake, SEEP/W and SLOPE/W

Comprehensive Diagnosis Method of the Health of Tailings Dams Based on Dynamic Weight and Quantitative Index

As a dangerous source of man-made debris flow with high potential energy, tailings dams can cause huge losses to people’s lives and property downstream once they break, and their safety control problem is particularly prominent. The health diagnosis of tailings dams is a complex and nonlinear problem full of uncertainty. At present, the health diagnosis of tailings dams is mostly qualitative evaluation or quantitative analysis aiming at a single index, so this study puts forward a comprehensive quantitative diagnosis method of tailings dam health based on dynamic weight. Slope stability, deformation stability and seepage stability are taken as project layers, and the diagnosis index system of the tailings dam is constructed. The quantitative methods of diagnosis indexes of project layers are proposed. For the dam slope stability project, the safety factor and the reliability index of tailings dams are determined based on the Monte Carlo method, which can consider the uncertainty of tailings material parameters. For the deformation stability project, the normal operation values of deformation rate and deformation amount are determined by analyzing the in situ observation data and combining them with the numerical simulation results. For the seepage stability project, through the analysis of seepage and stability, the relationship curve between the depth of saturation line and the safety factor of anti-sliding stability is established. The norms method is used to determine the quantitative standards for the diagnosis indexes of the basic layer. Based on the analytical hierarchy process method and the penalty variable weight method, the method of dynamic weight of the project layer index is proposed. The proposed methods are applied to a practical engineering project. The results show that the methods can accurately reflect the health status of tailings dams. This study provides a new method for evaluating the safety of tailings dams.

Dynamic risk assessment of slope stability of homogeneous earth-rock dam under action of multiple hazards

During actual service of the reservoir dam, there always appears a combination of water level fluctuations, rainfalls, and other hazard factors. During these times, the safety state of the dam is a dynamic process, and the dynamic risk assessment of dam slope stability which considers the time scale is of great importance. Therefore, in this study, the dynamical stability of the earth-rock dam under the combined action of multiple hazards is studied by using the Monte Carlo method, considering the spatial variability of the soil of dam and the coupling effect of the seepage field and the stress field. The failure probability and reliability index of dam under each working condition are calculated to determine the most dangerous working condition during the disaster-causing process. For the upstream slope, the most dangerous condition appears at the moment when the water level drops at a rate of 2 m/d with a 40 mm/d rainfall intensity, while the most dangerous condition of the downstream slope is that when the water level rises at a rate of 2 m/d with a 40 mm/d rainfall intensity. The influence of various disaster factors on the stability of dam is revealed and corresponding engineering early warning measures are proposed. This study realizes the dynamic risk assessment of dam slope stability under multiple hazards, avoids the limitation of evaluating the dam slope stability with a single safety factor, and provides a reference for risk analysis and emergency management of reservoir dams under the action of multiple hazards.

Stability evaluation of earth-rock dam reinforcement with new permeable polymer based on reliability method

The stability of earth-rock dam slope has always been the focus of engineers. The existing dam slope reinforcement measures mainly include anchor rods, anchor cables, soil nails, frame lattice beams, micro-piles and so on. However, the construction technology of these reinforcement measures is relatively complex and will cause disturbances to varying degrees in the construction process. In this paper, a new type of permeable polymer material is proposed for grouting anti-seepage reinforcement of dam slopes, and a stochastic field model of slope parameters after reinforcement is established. By analyzing the safety factor and failure probability of different types slope before and after reinforcement, it can be found that the safety factor of the slope can be greatly improved after the slope is reinforced with permeable polymer grouting; as the gradient increases, although the reinforcement effect decreases slightly, it can still have a good reinforcement effect; as the slope height increases, the reinforcement effect decreases gradually; in general, for medium and low slopes, the improvement effect of safety factor can reach about 50%; in the aspect of slope reinforcement of earth-rock dam, permeable high polymer is more suitable for middle and low earth-rock dam reinforcement.

Hysteresis of Dam Slope Safety Factor under Water Level Fluctuations Based on the LEM Coupled with FEM Method

Water level variations have caused numerous dam slope collapse disasters around the world, illustrating the large influence of water level fluctuations on dam slopes. The required indoor tests were conducted and a numerical model of an actual earth-filled dam was constructed to investigate the influences of the water level fluctuation rate and the hysteresis of the soil–water characteristic curve (SWCC) on the stability of the upstream dam slope. The results revealed that the free surface in the dam body for the desorption SWCC during water level fluctuations was higher than that for the adsorption SWCC, which would be more evident at higher water levels. The safety factor of the upstream dam slope initially decreased and then increased for the most dangerous water level as the water level rose and fell. The water level fluctuation rate mainly influenced the initial section of the safety factor variation curve, while the SWCC hysteresis mainly affected the minimum safety factor of the water level fluctuations. The desorption SWCC is suggested for engineering design. Furthermore, a quick prediction method is proposed to estimate the safety factor of upstream dam slopes with identical structures.

SEEPAGE AND SLOPE STABILITY ANALYSIS FOR SAFETY EVALUATION OF PIDEKSO DAM

The Pidekso Dam is one of the National Strategic Projects. The dam is located in Pidekso Village, Giriwoyo District, Wonogiri Regency, Central Java Province. The dam was designed as an earth-fill dam of zonal type with random fill and an upright core. Although the construction of a dam provides huge benefits, it may pose a potential hazard if collapses. Therefore, it is necessary to conduct a study to determine the safety of the Pidekso Dam in various conditions, including during an earthquake occurrence. The study analyzed the seepage on the main dam construction using Seep/W and dam-slope stability using Slope/W by reviewing the cross-section of the dam body and its foundation. The data used as the input in the analysis include the coefficient of soil permeability, soil cohesion, internal friction angle, and soil density based on field investigations and laboratory analysis. For the seepage analysis, manual calculations were also carried out using the Schaffernak and Casagrande method compared to the Seep/W results. From the results of the seepage analysis with Seep/W, the Pidekso Dam is safe against leakage with the largest discharge of 6.480×10 -4 m 3 /s at maximum water level. The safety factor against piping showed safe results with the lowest safety factor of 6.295 at the end of the filter drainage. In the dam stability analysis with Slope/W, several unsafe conditions have the lowest safety factor of 0.926 on the upstream slope at the minimum water level with MDE (Maximum Design Earthquake) of 0.25. In Makdisi-Seed analysis, the highest slope displacement value is 0.862 m with an earthquake magnitude of 8.25; Y/H (Y is the depth from the top of the dam and H is dam height) of 0.25. This value is smaller than the maximum limit of 2.00 m, hence the dam is still in a safe condition.