水下振动台水体振动特性试验研究

水下振动台丰富和拓展了振动台在工程结构抗震研究领域应用场景，但由于其局部振动、防水布扰动等因素，振动水体会发生畸变或失真，造成试验偏差。本文通过试验方法，共设计252个工况，分别考虑不同激励幅值、方向、频率、水深，研究台面范围及台面中心至水池边界水体振动特性。试验结果表明：防水装置对水体扰动影响主要体现在水平方向；垂直向正弦波激励时，低频（≤ 1 Hz）区间，水体振动呈“倒扣铁锅”形状，随频率增加（≥ 3 Hz），呈多波峰特性，频率越高波峰数越多，众多波峰随着激励幅值的增大会逐渐进行叠加放大，当超过阈值时，会产生坍塌现象；随水深增加，水体振动波峰存在下降趋势。试验研究为水下振动台设计及模型试验结果的可靠性评价等提供参考。

Experimental study on water vibration characteristics of underwater shaking table

The underwater shaking table enriches and broadens the application of shaking tables in the seismic research of engineering structures, but its vibrating water behaviors are often distorted due to its local vibration and the interference of its tarpaulin. In this work, a total of 252 working conditions were tested experimentally to study the characteristics of vibrating water in the zone from the center of the table to the water pool boundary, in the conditions of different excitation amplitude, direction, frequency, and water depths. The results show most of the influence and disturbance of the waterproof device is in the horizontal direction. For the case of vertical sinusoidal excitation, water vibration is in the shape of an inverted iron pot in low frequencies (≤ 1 Hz), while it features multiple wave peaks in medium or high frequencies (≥ 3 Hz) with more wave peaks in high frequencies. An increase in the excitation amplitude causes more wave peaks to be gradually superimposed together and amplified, and a collapsing phenomenon will occur when a certain amplitude threshold is exceeded. The amplitude of water vibration peaks shows a downward trend with an increasing water depth. This study demonstrates how to evaluate and improve the model tests on an underwater shaking table.