Abstract
The distribution of hydrodynamic pressure acting on the structural face of a dam significantly influences the stability of the dam. The present study investigates the development of the hydrodynamic pressure acting on the surface of a dam at different heights with respect to time during earthquakes with different dominant frequencies using a shaking table. The results demonstrate that the variation in the hydrodynamic pressure significantly follows the seismically accelerated wave motion in the absence of resonance. However, under conditions of resonance, the fluctuations in the hydrodynamic pressure exhibit similarities with a sine wave, and the positive peak values present some hysteresis. The experimental pressure values in the absence of resonance present parabolic distributions with respect to the water height that are in good agreement with the corresponding hydrodynamic pressures determined by Westergaard’s equation, while conditions of wave resonance produce a uniform distribution of hydrodynamic pressures with greater values and much longer periods of increased hydrodynamic pressure than the case of nonresonance. In addition, the seismic frequency, fundamental frequency of the reservoir, maximum peak seismic acceleration, and initial water depth are treated as variables. An empirical equation is derived to predict the maximum hydrodynamic pressure in conjunction with wave resonance conditions.
Highlights
The motion of seismic-induced hydraulic structures can generate considerable hydrodynamic pressure on the structural face of a dam, which can significantly affect its stability
We note that the employment of an excitation frequency far from the fundamental frequency of the water body resulted in the synchronization between the seismic acceleration wave response and the hydrodynamic pressure response, such that the hydrodynamic pressure was mainly affected by the amplitude of the seismic acceleration
EQ1 and EQ2, were utilized to obtain different hydrodynamic pressures under equivalent conditions, where the dominant frequency of EQ1 was much greater than the fundamental frequency of the water body employed in the experiments and that of EQ2 was nearly equivalent to the fundamental frequency
Summary
The motion of seismic-induced hydraulic structures can generate considerable hydrodynamic pressure on the structural face of a dam, which can significantly affect its stability. Westergaard [1] first derived an expression for the hydrodynamic pressure exerted on the vertical upstream face of a concrete dam subjected to a single harmonic excitation. Many current engineering designs have continued to employ a simplified form of this formula to account for hydrodynamic pressure loads [2,3,4]. In 1953, Zangar [5] developed an experimental solution for the same problem using an electrical analogue and reported extensive results for a variety of nonvertical upstream faces. Chwang and Housner [6, 7] solved the hydrodynamic pressure problem for a more general dam configuration using the momentum method and two-dimensional (2D) potential flow theory, respectively. The results generated by these works were more or less equivalent to the results of Westergaard
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