Broadband attenuation of low frequency acoustic waves in compact structure designs is a challenging issue, especially in the application to seismic waves. In this work, we propose a new seismic metamaterial constituted by a combination of two different attenuating structures, namely pillars above the ground and core-shell inclusions embedded in the soil. As compared to the two constituting parts, this structure enables us to broaden the bandgap while shifting it towards lower frequencies. Additionally, the analysis of the symmetry of the excited Rayleigh wave and the eigenmodes in the dispersion curves reveal that the frequency range of efficient wave attenuation in transmission is much wider than that of the corresponding bandgap. Finally, gradient combined metamaterial is designed to achieve wave attenuation in a broadband range of [4.3, 20.0] Ηz while the unit cell size keeps compact, of the order of 2 m. The results show practical and economic applications in ground surface vibration isolation to protect large infrastructures or civil engineering architectures.

紧凑结构设计中低频声波的宽带衰减是一个具有挑战性的问题，尤其是在地震波的应用中。在这项工作中，我们提出了一种新的地震超材料，它由两种不同的衰减结构组合而成，即地面上的柱子和嵌入土壤中的核壳包裹体。与两个组成部分相比，这种结构使我们能够加宽带隙，同时将其移向较低的频率。此外，对激发瑞利波的对称性和色散曲线中的本征模式的分析表明，传输中有效波衰减的频率范围比相应的带隙宽得多。最后，梯度组合超材料旨在实现[4.3, 20]宽带范围内的波衰减。0] Hz，而晶胞尺寸保持紧凑，约为 2 m。结果显示了地表振动隔离在保护大型基础设施或土木工程建筑方面的实际和经济应用。