Rubber-sand infilled soilbags as seismic isolation cushions: experimental validation

Abstract

This study proposes soil bags filled with a rubber sand mixture (SFRSM) to enhance the stability of rubber sand layers for effective seismic isolation. To evaluate the dynamic characteristics of the SFRSM, large-scale cyclic simple shear tests were conducted to investigate the effects of rubber content, vertical pressure, shear displacement amplitude, fill percentage, and laying scheme. Furthermore, shaking table tests were carried out to evaluate the impact of vibration intensity and frequency on the seismic isolation of SFRSM layers. The results indicate that (1) SFRSM exhibits lower shear modulus and higher damping than traditional rubber-sand layers, suggesting superior seismic isolation and energy dissipation capabilities. (2) The dynamic characteristics of the SFRSM were influenced by the fill percentage and laying scheme, indicating the potential for creating resilient isolators suited to various conditions. (3) The isolating efficacy of SFRSM is due to its effective damping of high-frequency vibrations, with the threshold frequency reducing as more SFRSM layers are implemented. In summary, these experimental results provide evidence that the proposed innovative strategy enhances the strength and vertical stiffness of the original rubber-sand layer, making it well-suited for seismic design applications in low-rise buildings in less-developed regions.