Abstract: 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.

Key words: seismic isolation, vibration reduction, periodic structure, quaternary structure, local resonance, pile barriers