Tunable periodic surface wave barriers via water level variation

The bandgap characteristics of traditional periodic wave barriers are limited by their fixed geometric shape and material properties, making them difficult to adapt to complex broadband vibration sources that may change at any time. To address this issue, this paper proposes a tunable surface wave periodic vibration isolation barrier based on water level variation. This structure achieves continuous tunability of the bandgap by regulating the water level in the trench, thereby flexibly responding to changes in vibration sources of different frequencies. Using the finite element method, the paper systematically analyzes the mechanism by which water level variation regulate the position and width of the bandgap, and validates its vibration isolation performance through model experiments. The results show that as the water level rises, the bandgap shifts toward lower frequencies. By utilizing the bandgap differences of periodic unit cells with different water levels to construct a broadband vibration isolation barrier, complementary coverage of the bandgap can be effectively achieved. Continuous broadband attenuation is realized in the range of 5.2 Hz to 67.3 Hz, with a maximum displacement attenuation of 40 dB. Further application of this structure to simulate responses to real seismic waves and on-site subway environmental vibrations was conducted. By matching the corresponding variable water level periodic wave barriers to the source frequency, targeted attenuation of the target frequency was achieved. The experimental results showed good consistency with theoretical predictions, verifying the feasibility of the water level-regulated bandgap mechanism in actual engineering applications. This study provides a foundation for constructing efficient, adjustable, and broadbandgap structures.