Narjes Soltani

In this research, a novel hybrid methodology is proposed for predicting the structural response of high concrete arch dams, combining the Discrete Element Method (DEM) with the Locally Estimated Scatterplot Smoothing (LOESS) technique. A structured calibration strategy is employed during the numerical model preparation to enable the generation of a wide range of reliable output variables for training and prediction. The methodology is then applied to the El Atazar arch dam to demonstrate its capability to forecast displacement and stress responses. The study reveals that using the current air temperature as an input variable is not adequate for representing the thermal behavior of the dam body; instead, the mean air temperature over a specified period yields significantly better results. Additionally, the findings highlight the importance of the loading path and the dam’s initial state in determining its structural response. The developed model shows a strong agreement between predicted and observed data, demonstrating its effectiveness in capturing the nonlinear behavior of high concrete arch dams. Compared to traditional parametric models commonly used for dam deformation analysis, the proposed framework offers greater flexibility in representing nonlinearity while requiring less training data, making it ideal for dams with limited monitoring records, such as older dams or newly operated ones.

The structural integrity of concrete arch dams is critical to ensuring their long-term stability and safety, particularly under seasonal thermal variations. In this study, the effect of contraction and construction joint quality on the static performance of concrete arch dam safety is evaluated. To achieve this, two different approaches are followed: the first approach focuses on global stability through the calculation of the shear strength reduction factor for certain structural joints, while the second approach assesses the local stress–deformation behavior after incorporating physical gaps into the specific joints. The proposed methodology is applied to the numerical model of a typical concrete arch dam. The results of the global safety evaluation reveal that, in the winter and summer scenarios, the joints in the upper half and middle third of the dam height, respectively, have the most significant influence on the dam stability. The local approach demonstrates that while one type of performance index might indicate acceptable performance, another could reveal underlying safety concerns. Both approaches aim to provide a comprehensive understanding of the dam’s structural integrity under varying conditions, supporting informed decision-making for maintenance and safety measures.

In this paper, a discussion on the applicability and limitations of the limit equilibrium method is presented. In this manner, the reliability of a concrete arch dam-foundation system under static loading is evaluated by considering a set of potentially moveable rock wedges in the foundation. The safety of the system is assessed utilizing a quasi-analytical method, which employs the limit equilibrium method and numerical analysis to calculate the sliding safety factors and the dam trust forces, respectively. The reliability is evaluated using the Latin Hypercube Sampling method. Random variables in the system are the friction angle, cohesion, and the Grout Curtain Efficiency Coefficient. In the end, the influence of two parametric variables of discontinuities, elastic slip and rock mass deformability modulus, on the rock wedges’ sliding safety factor is evaluated by comparing the results of the quasi-analytical method with the purely numerical method. The results show that in the case of complicated geotechnical conditions, the limit equilibrium method may not reflect real-world failure scenarios.