Abstract: Damage of tunnel in clay induced by underlying normal faulting is not tully understood. I his study carries out a numerical study on this problem using total stress analysis method. Both of the calculated results and centrifuge data show that deformation of the clay layer is classified as a stationary zone, a shearing zone and a rigid body zone. The area of differenti al, ettlement zone decreases with depth, resulting a reduction in area of influencing zone and an increase in extent of damage with depth. When the tunnel surface is tied to the surrounding soil, the tunnel nearby the bedrock fault is mainly suhiected to bending while the area far from the bedrock fault is mainly subjected to tension. At the tunnel crown, tension strain is observed on the footwall side while compression strain on the hanging wall side.