Design of high concrete gravity dam and its stability analyses for varying earthquake intensities

Abstract

Gravity dams are solid concrete structures that maintain their stability against design loads from the geometric shape and the mass and strength of the concrete. The various forces affecting the design of a gravity dam are dead load or stabilizing force, headwater and tailwater pressures, uplift, temperature, earth and silt pressures, ice pressure, earthquake forces, wind pressure, subatmospheric pressure, wave pressure, and reaction of foundation. The design and evaluation of hydraulic structures for earthquake loading must be based on appropriate criteria that reflect both the desired level of safety and the choice of the design and evaluation procedures. Thus, the main aim of this study is to design high concrete gravity dams for varying earthquake intensities by keeping all other design constraints unchanged, and to analyze its stability. In Bangladesh, the entire country is divided into 3 seismic zones depending upon the severity of the earthquake intensity. In this research, the moments at the toe of a gravity dam in Seismic Zone II of Bangladesh, are calculated with earthquake forces, keeping all other design constraints unchanged. Considering uncertainty and severity of earthquake intensities, the horizontal earthquake intensities are perturbed from 0.10g-0.30g with 0.05g increment, keeping other loads unchanged, in order to examine the stability and stress conditions of the dam. The results of the horizontal earthquake intensity perturbation show that the stability of the gravity dam endangers with the increment of horizontal earthquake intensities, unless the dam section is enlarged. Thus, it can be concluded that the stabilizing moments are found to decrease significantly with the increment of horizontal earthquake intensity that may lead to endanger the stability of the dam, and larger dam section is needed to make it safe against possible failure.