Dynamic Characteristics of Adjacent Tunnel and Surroundings Under the Vibration of Trains in the First Tunnel with Different Buried Depths

This paper discussed the effect of different buried depth (B) of the twin-tunnels using scale experimental model and discrete element method (DEM). The diameter (D) of the twin-tunnels is 6.2 m, and the spacing between the two tunnels is 0.25 D. Five cosine functions are used to simulate the vibration load of the train passing through the first tunnel, which is very convenient to simulate the longitudinal movement of the train in two-dimensional DEM. In the 1/20 scale experimental model, self-made gypsum rings were used to simulate the tunnel liner, and the vibrator applied the train load. Surface uplift, the displacement and deflection of sleepers, as well as the displacement, velocity, acceleration and strain of the tunnel's liner and the surroundings are discussed with different buried depths twin-tunnels (0.5 D, 1.0 D, and 1.5 D). It is found that the buried depth of the tunnel will seriously affect the effect of train vibration on adjacent tunnels. The displacement, velocity, and acceleration in the vertical direction are much larger than the values in the horizontal direction. The deflection of sleepers during vibration will cause an unsafe run of the train in adjacent tunnel and pose risks to liner. It is suggested to build twin-tunnels with larger buried depth if the economy and technology requirements are satisfied. The research is expected to prove a reference for similar projects.