近场和远场地震动作用下双层竖向重叠地铁隧道地震反应特性

Seismic Response Characteristics of the Double-Layer Vertical Overlapping Metro Tunnels under Near-Field and Far-Field Ground Motions

基于江苏省的地震环境,研究近、远场地震动作用下的双层竖向重叠地铁隧道的地震反应特性,并与单层地铁隧道的地震反应特性进行比较。结果表明:在近场地震动作用下上下层隧道之间的相互作用对隧道的相对水平位移差具有放大作用,而在远场地震动作用下双层隧道的相对水平位移差与单层隧道的基本相同;在近、远场地震动作用下,上层隧道的相对水平位移差要比下层的大得多;在近场地震动作用下存在隧道拱肩外侧的地震应力大于拱肩内侧地震应力的现象,而在远场地震动作用下地铁隧道拱肩内侧的地震应力值最大;在近场地震动作用下双层隧道下层的地震应力幅值要比上层的地震应力幅值大,在远场地震动作用下则相反;在近、远场地震动作用下双层竖向重叠地铁隧道底部的峰值加速度与浅埋或深埋单层隧道的基本相同。

According to the seismic environment of Jiangsu Province, the seismic response characteristics of the double-layer vertical overlapping metro tunnels under near-field and far-field ground motions were studied and compared with those of the single-layer metro tunnels. Results show that the interaction between the upper layer and lower layer tunnels plays a significant amplification role on the relative horizontal displacement under near-field ground motion. However, the relative horizontal displacement of the double-layer tunnel is almost the same as that of the single-layer tunnel under far-field ground motion. The relative horizontal displacement of the upper layer overlapping tunnel is far larger than that of the lower layer under both near-field and far-field ground motion. The seismic stress at the lateral side of the tunnels is larger than that at the medial side under near-field ground motion, while the stress at the medial side of the tunnel is the largest all along under far-field ground motion. The seismic stress amplitude of the lower layer is larger than that of the upper layer under near-field ground motion, and under far-field ground motion the condition is opposite. The peak acceleration at the bottom of the double-layer vertical overlapping metro tunnels under near-field and far-field ground motions is almost the same as that of shallow-buried or deep-buried single-layer tunnels.