Dynamic behavior of geocell-reinforced rubber sand mixtures under cyclic simple shear loading

Abstract

Due to the attributes of low shear modulus and high initial damping, rubber sand mixtures (RSM) can be used as a soil alternative to reduce ground motions when seismic loads are of great concern. However, when RSM is used as a vibration isolation material for geotechnical seismic isolation systems, it suffers from a lack of load-bearing capacity. To overcome this, a three-dimensional interconnected geocell (one type of geosynthetics) is placed within RSM to increase the vertical confinement of the system. In this technical note, to investigate the shear modulus and damping ratio of geocell-reinforced RSM, large-scale cyclic triaxial tests were conducted on specimens prepared with four granulated rubber contents (by weight) and sheared under different cyclic shear strain amplitudes. The results show that Geocell reinforcement can restrict the development of local shear bands in the specimen, weaken the anti-S-shaped characteristics of hysteresis loops and enhance the damping ratio of RSM at large strain amplitudes. The tuck net effect causes an increase in the normal stress of both contact particles, and then leads to the degradation rate of the maximum shear modulus of RSM varying with the rubber content and vertical pressure. The normalized shear modulus degradation curves show the influence range of geocell reinforcement, and demonstrate that a rubber content of 20% for reinforced specimen may be an optimal value from the perspective of the stability of dynamic properties. Additionally, the quantitative analysis of the effect of geocell reinforcement on the mechanical behavior of RSM can provide a reference for subsequent theoretical research and engineering applications.