以太湖隧道为工程背景，运用大质量法建立类矩形隧道结构的三维地震动分析模型，研究在水平地震作用下隧道结构的内力变化规律及位移响应规律。研究表明： 1)类矩形断面结构在水平向地震作用下的结构内力在侧墙底部最大，且弯矩是主要控制内力； 2)过渡段1和过渡段2是隧道结构在地震作用下受力的薄弱点，且过渡段1产生的内力最大； 3)从浅埋段至深埋段，隧道结构顶底板层间位移角逐渐增大，最大层间位移角均小于规范限值。研究成果可为太湖隧道的抗震设计提供参考。

A 3D seismic analysis model of Taihu quasirectangular tunnel is established based on large mass method, so as to the variation rules of internal force and displacement rules of the tunnel structure under the action of horizontal seism. The study shows that: 1) The structural internal force in sidewall bottom is the largest under the horizontal seismic action; and the bending moment plays the main control force. 2) Transition section No. 1 and 2 are the weak points of the tunnel under the seismic action; and the maximum internal force is located in transition section No. 1. 3) The story drift angle increases from the shallowburied section to the deepburied one; and the maximum story drift angle is less than the standard limit. The results can provide references for seismic design of Taihu Tunnel.