To reveal the corresponding relationship between the void beneath the tunnel bottom and the longitudinal deformation of the metro tunnel

a model test of circler tunnel is carried out under the research background of Xi'an Subway passing through ground fissure active zones. The law of the longitudinal strain and the vertical displacement of the tunnel are studied caused by the different profile activity patterns of ground fissure belts. With the increase of the dislocation between the hanging wall and the foot wall of ground fissure

the test results show that the expansion process of the separation between the bottom of tunnel and the soil layer under the tunnel can be divided into three stages

i.e. co-deformation stage

the initial stage of void and the development of void. In view of different profile activity situations of ground fissures

the stress in the structure presents variance considerably. Different designs are suggested to different profile patterns of ground fissure belts. Under the law of stress and strain of the tunnel in the model test

the trend of the void beneath the tunnel can determined by monitoring the stress of structure. The results can provide reference for the structure design and the safe operation of metro tunnel.