Stability Analysis Of Gravity Dam Research Articles

A multi-objective-optimization based importance sampling method and its application in seismic stability analysis of gravity dam

The stable reliability analysis of dams is a challenging topic in geotechnical engineering safety. Because there are more complex system failure modes and high-dimensional parameters in large solid structures, it is difficult to calculate failure probability efficiently and accurately using general reliability analysis methods. Most methods suffer from complex iterative processes and the curse of dimensionality. In this study, an improved importance sampling method based on multi-objective optimization is proposed and applied to reliability analysis for dam sliding. The optimization function is constructed from the limit state surface and the original probability density. The optimal sampling center is selected from the optimization results by considering the dominant performance function as well as the coefficient of variation of the weight function. Four numerical examples and a case study of the sliding stability of a gravity dam demonstrate the accuracy and efficiency of the proposed method. The results show that the proposed method is not sensitive to the specific multi-objective optimization algorithm used. Simulations using multiple sampling centers perform better overall than simulations using a single sampling center. In particular, the proposed method remains applicable to parallel systems with 20 high-dimensional parameters that are virtually immune to the curse of dimensionality.

Gravity dam analysis using particle swarm optimization method

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

Stability analysis of gravity dams under uncertainty using the fuzzy sets theory and a many-objective GA

Uncertainties in the analysis and design parameters of a gravity dam are spread out over the system and make the stability safety factors uncertain too. To analyze the effects of such uncertainties on the dam performance, a conceptual model based on the fuzzy sets theory is introduced here. The input uncertainties are simulated by triangular fuzzy numbers and introduced to the governing equations. To evaluate the extreme values of the dam safety factors, a many objective optimization problem is formed. To solve the problem efficiently, a many-objective genetic algorithm (MOGA) is coupled to the dam stability analysis model. The model is able to estimate all extreme values of the dam safety factors in only one single optimization run. An example gravity dam with and without uncertainty is analyzed respectively by the traditional and the fuzzy approaches. It is found that small input uncertainties can highly influence the analysis responses and, the proposed method can efficiently capture all safety factors uncertainties. For example, the simulations revealed that only± 10% uncertainty in the dam design parameters would lead to about –346 to +146 % uncertainty in the stability safety factors.

Sliding stability analysis of gravity dam founded on rock mass with impersistent joint set

This article aims to evaluate the sliding stability of a gravity dam with a foundation failure mechanism characterized by a pre-existing subhorizontal joint set acting as a sliding plane, and with a potential failure path that extends through the rock mass. The safety factor is estimated using a combination of joints and rock mass strengths, using the criteria of Barton and Choubey and Hoek and Brown, respectively. Nonassociative flow rule in the rock mass has been incorporated using a constant dilation angle. The finite difference program FLAC 6.0 is employed to validate the model. The proposed analytical model provides results that are very similar to those computed with FLAC; however, as the new formulation can be implemented in a spreadsheet, the computational cost of the proposed model is significantly smaller, hence allowing to more easily conduct parametric analyses of the influence of the different input parameters on the dam’s safety.

Stability analysis of concrete gravity dam on complicated foundation with multiple slide planes

A key problem in gravity dam design is providing enough stability to prevent slide, and the difficulty increases if there are several weak structural planes in the dam foundation. Overload and material weakening were taken into account, and a finite difference strength reserve method with partial safety factors based on the reliability method was developed and used to study the anti-slide stability of a concrete gravity dam on a complicated foundation with multiple slide planes. Possible slide paths were obtained, and the stability of the foundation with possible failure planes was evaluated through analysis of the stress distribution characteristics. The results reveal the mechanism and process of sliding due to weak structural planes and their deformations, and provide a reference for anti-slide stability analysis of gravity dams in complicated geological conditions.

Stability Analysis of Gravity Dam on Soil Foundation

For small and medium sized water conservancy project, gravity dam on soil foundation is a comparatively economic and reasonable dam structure. Based on project case, the author discusses in this paper the seepage-proofing and anti-sliding stability of the gravity dam on soil foundation, focusing on calculation of anti-sliding stability of deep stratum, selection of soil pressure and effective measures for improving the anti-sliding stability of the gravity dam on soil foundation.

3D stability analysis of gravity dams on sloped rock foundations using the limit equilibrium method

A convenient approach to performing stability analysis of concrete gravity dams is the so-called two-dimensional “gravity method.” However, concrete gravity dams located in valleys with sloped rock foundation abutments behave as three-dimensional (3D) structures and are often able to share compressive and shear loads between adjacent monoliths, especially when shear keys are present. A general 3D limit equilibrium method was developed in this study to compute global sliding safety factors (SSFg) by considering sequential load redistribution among adjacent monoliths when individual monoliths have mobilized their sliding strength. Two validation examples of the sliding safety assessment of existing dams are presented to illustrate the accuracy and efficiency of the proposed approach compared to that of the full 3D numerical analyses conducted using the distinct element method. It is shown that gravity dams may be formed by individual monoliths on sloped rock foundations that will slide if considered as isolated structures but will constitute a stable assembly when the load-sharing capabilities of monoliths are recognized in the analysis.

Deep Sliding Stability Analysis of Gravity Dam Based on FEM Strength Reduction

Anti-sliding stability in deep foundation of Shatuo gravity dam is studied in this paper. Combined with the static and dynamic analysis of anti-sliding stability in deep foundation of gravity, strength reduction finite element method is used to do static calculation of anti-sliding stability firstly. The horizontal seismic strength can be gotten in order to be applied to the baseplane based on response spectrum method, thus dynamic calculation of anti-sliding stability can be carried out. The calculation result shows that static and dynamic anti-sliding stabilities in deep foundation of gravity meet the requirements.

Some characteristic features of stability analysis of gravity dams in narrow canyons. In Rock foundations of hydraulic structures : In Russian. 7F, 1T, 3R. PROC. HYDROPROJ. INST. MOSCOW, V33, 1974, P41–51

Some characteristic features of stability analysis of gravity dams in narrow canyons. In Rock foundations of hydraulic structures : In Russian. 7F, 1T, 3R. PROC. HYDROPROJ. INST. MOSCOW, V33, 1974, P41–51