Document Type : Research Paper
Author
Department of Water Engineering, Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran
Abstract
Concrete gravity dams must maintain adequate resistance against hydraulic and seismic loading to ensure structural safety and long-term operational performance. Reliable assessment of sliding, overturning, uplift pressure, and stress concentration is therefore essential, particularly under extreme flood and earthquake conditions. In this study, the stability behavior of the Bratsk concrete gravity dam was investigated using the CADAM computational platform under normal operation, flood loading, and pseudo-dynamic seismic conditions. The methodology involved two-dimensional static and pseudo-dynamic analyses based on rigid-body equilibrium and modal force combination principles. Hydrostatic, hydrodynamic, uplift, sediment, self-weight, and seismic inertia forces were incorporated into the numerical model, and safety factors were evaluated at multiple joints along the dam–foundation interface. In addition, a normalized sensitivity index (NSI) framework was developed and integrated with the CADAM outputs to quantify the relative influence of governing mechanical and hydraulic parameters, including foundation friction, uplift efficiency, and hydrodynamic shear forces, on the stability response of individual joints. The results showed that the dam remained stable under normal operating conditions, whereas flood loading generated the most critical response, with the minimum Sliding Safety Factor (SSF) decreasing to 0.856 at Joint 9 and the minimum Overturning Safety Factor (OSF) reaching 1.423 at Joint 10. Pseudo-dynamic analyses further indicated that inertial forces became concentrated near the dam base, where combined modal forces exceeded −16,000 kN. The NSI-based sensitivity analysis reveals that frictional resistance (NSI = +1.00) and hydrodynamic shear forces (NSI = –0.85) at Joint 9, as well as uplift pressure effects (NSI = –0.72) at Joint 10, are the dominant parameters affecting stability.. The proposed NSI-enhanced framework improves the interpretation of localized instability mechanisms and supports more effective prioritization of reinforcement and foundation treatment strategies in concrete gravity dams.
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