Abstract: A composite rigid-flexible pile-supported retaining wall (CRF-PSRW) including EPS cushion was proposed aiming for the treatment of high-filled expansive soil subgrade slope. The numerical model of CRF-PSRW used for high-filled expansive soil subgrade was established by FLAC3D. Based on the thermal-mechanical coupling model, the deformation of expansive soil was simulated with the change of humidity. The mechanical and deformation behaviors of CRF-PSRW in five different working conditions were compared and analyzed. The effects of thickness and stiffness of EPS cushion on the earth pressure and horizontal displacement of the CRF-PSRW were further investigated. The results show that the CRF-PSRW can obviously reduce the earth pressure of retaining wall, bending moment and shear force of anti-slide pile, and horizontal displacement of the structure. However, settlement and horizontal displacement of pavement are found to significantly increase. The compression amount of EPS cushion increases with the decrease of elastic modulus or increase of thickness. Then larger lateral deformation of the expansive soil is permitted, leading to reduction of the force and deformation of CRF-PSRW. In order to give full play to the decompression effect of flexible EPS cushion, the conditions of thickness and modulus of elasticity must be satisfied at the same time.The single cushion stiffness index is not enough to reflect the influence of EPS cushion..

Key words: composite rigid-flexible pile-supported retaining wall, EPS cushion, expansive soil, numerical simulation