Impacts of reinforced wall on nearby excavation-induced ground and tunnel responses: A centrifugal and numerical study

Reinforced wall is widely adopted to protect existing structures subjected to nearby underground constructions. This study carried out two three-dimensional centrifuge tests (T-W with reinforced wall and T-0 without rein-forced wall) and numerical back-analyses to investigate the ground and tunnel responses due to a nearby excavation in dry sand. In terms of the changes of earth pressures on the tunnel, the reinforced wall shows slight impacts at most positions, but areas between right heel and invert, and between left shoulder and crown. Tunnel heaves and longitudinal bending moments in vertical direction are slightly decreased due to the reinforced wall, while horizontal displacements and longitudinal bending moments in horizontal direction are appreciably increased. In terms of the effectiveness of the reinforced wall on mitigating tunnel horizontal displacements, four zones can be divided from shallow to deep: positive, negligible, negative, and negligible. Arching effects induced by the diaphragm wall deformations and continuous reinforced wall displacements are found to be the mech-anism behind the reinforced wall-induced increases in tunnel horizontal displacements.