Undrained cyclic responses of granulated rubber-sand mixtures

Undrained cyclic responses of rubber-sand mixtures are essential for its applications in earthquake-prone areas. Hence, the present study is intended to examine the liquefaction behaviour and modeling the undrained cyclic responses of granulated rubber-sand mixtures with size of sand and granulated rubber less than 2 mm. The stress controlled undrained cyclic triaxial tests followed by undrained monotonic tests were carried out on mixtures with rubber content 0% (pure sand), 10%, 20%, 30%, 50%, 75%, and 100% (pure rubber) to examine liquefaction and post-liquefaction behaviour of the mixtures. The test results show that the mixture possesses higher liquefaction resistance when rubber content is between 30% and 50%. The post-liquefaction behaviour of the mixtures identified as pseudo-elastic-hardening and its corresponding modulus is found to vary marginally with its static modulus. In addition, the post-liquefaction strength of the mixtures is observed to be more than that of sand at the lower axial strain. Further, the undrained responses such as hysteretic behaviour and excess pore water pressure are modeled using Masing's rule and the relation between degradation index (δ) and excess pore water pressure ratio (r_u), respectively. The proposed model effectively predicts the cyclic behaviour of mixtures with rubber content between 10% and 75%.