周期性四组元局域共振桩带隙特征及隔振性能研究

基于既有的三组元局域共振结构，考虑到岩土材料流塑性及弹塑性特征，提出一种由管桩、软体层、桩芯和基体组成的四组元局域共振桩结构，并基于周期性理论，利用频散曲线分析了管桩密度、弹性模量、厚度对四组元结构带隙特征影响。研究发现：相比于无管桩的三组元结构，带管桩的四组元结构更加容易出现完全带隙，且管桩只对带隙上边界产生影响；相比于管桩密度，管桩弹性模量可对四组元结构带隙产生质变影响，影响程度更大；通过四组元结构带隙边界点模态分析，确立了四组元结构带隙计算公式。通过时域分析发现，相比于三组元结构，四组元结构在带隙内振动衰减效果可提升近30%，其内在原因是四组元结构中管桩提高了基体整体刚度，从而有效地预防了基体“击穿”带及泄露波的出现。相关研究可为新型局域共振结构设计及隔振效果改善提供新思路。

Study on band gap characteristics and vibration isolation of local resonance pile with periodic four component

Based on the existing three component local resonance structure, a four component local resonance pile structure composed of pipe pile, soft layer, pile core and matrix was proposed considering the flow plastic and elastic-plastic characteristics of geotechnical materials. By introducing the periodic theory, the effects of pipe pile density, elastic modulus and thickness on the band gap characteristics of four component structure were analyzed by using the dispersion curve. Compared with the three component structure without pipe pile, the four component structure with pipe pile is more prone to complete band gap, and the pipe pile only affects the upper boundary of band gap. The modulus of pipe pile has a qualitative and even greater effect on the band gap of quaternary structure comparing with the density of pipe pile. By modal analysis, the calculation formula of the band gap boundary for the quaternary structure was established. Through time domain analysis, it is found that compared with the three component structure, the vibration attenuation effect of the four component structure in the band gap can be improved by nearly 30%. The reason is that the pipe pile in the four component structure improves the overall stiffness of the matrix, so as to effectively prevent the occurrence of "breakdown" band and leakage wave of the matrix. This study provides a new insight into the design of new local resonance structure and the improvement of vibration isolation effect.