Research on the Seismic Isolation Effect of the Ring Spring–Friction Pendulum Bearing in the Dakai Underground Subway Station

Abstract

During strong earthquakes, the vertical seismic force becomes an essential factor affecting shallow underground structures that cannot be ignored. In this situation, it is proposed that ring spring–friction pendulum two-way seismic isolation bearings be set up at the bottom of such structures. Targeting the Dakai underground station and the Kobe earthquake, a soil-structure force model was established based on the damage to the underground structure and dynamic simulation was carried out using Abaqus software. The advantages of the ring spring–friction pendulum bearing over the ring spring bearing alone and the friction pendulum bearing alone were compared. The simulation results showed that the structure displayed a good seismic isolation effect in both horizontal and vertical directions after setting the ring spring–friction pendulum bearing. The deflection in the midspan of the roof reduced to less than 5 cm, the horizontal relative displacement of the structure reduced to less than 3 cm, there was no obvious damage to the structure, the axial pressure ratio of the mid-pillar reduced to less than 0.5, the axial force on the mid-pillar reduced by more than 50%, and the shear force reduced by more than 30%. In addition, by comparing the damage to the structure after setting the annular spring bearing and the friction pendulum bearing, we found that a vertical seismic isolation device is more crucial than a horizontal seismic isolation device for shallow underground structures. Setting a vertical damping device can make the structure retain part of the ductility and reduce the damage to the structure, so the ground vertical seismic mitigation design should be strengthened when a shallow underground structure is designed.

Correlation Analysis of Tunnel Deformation and Internal Force in the Earthquake Based on Tunnel Inclination

“…The tunnel is constructed using the shield method, and the whole ring of segment is divided into one top block F (16 • ), two adjacent blocks L (65 • ), two standard blocks B (65 • ) and one bottom block (84 • ). The blocks are connected by M30 bolts, with an outer diameter of 6.2 m and an inner diameter of 5.5 m. The depth of burial of the centre of the tunnel is −17.1 m and the soil layers through which the tunnel passes are mainly layer 4 ⃝ soil and layer 5 ⃝ 1 soil. The cross section of the tunnel and soil layers are shown in Figure 1.…”

“…As a result, traditional perceptions of the seismic performance of underground structures have been overly optimistic. However, the occurrence of the Kobe earthquake [4][5][6] in Japan in 1995 raised concerns about the seismic performance of underground structures. In the Kobe earthquake, the drainage pipe system, one of the lifelines of modern cities, suffered fractures, cracks and joint separation, resulting in a loss of function.…”

Correlation Analysis of Tunnel Deformation and Internal Force in the Earthquake Based on Tunnel Inclination

“…As a result, traditional perceptions of the seismic performance of underground structures have been overly optimistic. However, the occurrence of the Kobe earthquake [4][5][6] in Japan in 1995 raised concerns about the seismic performance of underground structures. In the Kobe earthquake, the drainage pipe system, one of the lifelines of modern cities, suffered fractures, cracks and joint separation, resulting in loss of function.…”