Examination of earth pressure reduction mechanism using tire-chip inclusion in sandy backfill via numerical simulation

Tire chips have special features as geomaterials, as they are lighter than soil particles, highly compressible, and softer than sand. In this study, the effect of tire chips used as a compressible inclusion in backfill on the load reduction against retaining walls is numerically investigated. It is known that a reduction in earth pressure in backfill is realized by achieving a quasi-active or intermediate active state; and thus, a field test of this behavior is herein numerically simulated. The influence of the Poisson's ratio and elastic modulus of tire chips on the reduction in earth pressure against retaining walls is examined by assuming that tire chips can be modeled as an elastic body. The numerical simulation reveals that the attainment of the active state in sandy backfill is primarily due to the light-weight nature of tire chips, along with their low Young's modulus and Poisson's ratio. Furthermore, the influence of friction at the bottom of the backfill mass is also considered, and the earth pressure reduction mechanism incorporating this factor is also numerically investigated.