Model Test on Effect of Ground Fissure on the Behavior of Oblique Two-Section Subway Tunnel

The dynamic interaction between the ground fissure and an oblique two-section horseshoe-shaped subway tunnel under the subway dynamic load was investigated based on a series of model tests in this study. The results indicated that the subway subway-induced vibration attenuated in different degrees when propagating in the directions in the soil layer, while the ground fissure had an attenuation effect on subway vibration. Furthermore, the vibration of the soil layer below the tunnel near the ground fissure was stronger than that of the upper soil layer, and the vibration response at the tunnel bottom was stronger than that of the arch waist and the tunnel crown. The additional contact pressure between the tunnel bottom and the soil was relatively large when the ground fissure was not active, while the additional strain at the top and bottom of the tunnel caused by the excitation was small. Moreover, when the hanging wall of the ground fissure descended, the additional contact pressure at the tunnel crown in the hanging wall and the tunnel bottom in the footwall significantly increased, and a negative additional stain was identified at those two positions. Meanwhile, a positive additional stain was identified at the tunnel crown in the footwall and the tunnel crown in the hanging wall, increasing with the descent of the hanging wall.