依托成都龙泉山一号隧道,运用等效荷载法进行数值模拟计算,对不同开挖步序、不同净距下隧道施工对既有隧道结构的动力响应特性进行了研究,结果表明:(1)由于缺少临空面,后行隧道开挖步序1对衬砌结构影响程度最大,而步序2和步序3对结构的影响较小;(2)不同开挖步序下,后行隧道结构的振速峰值较大处主要出现在迎爆侧的边墙、拱腰和拱脚位置,监测点振速最大值为5.665 cm·s^-1;(3)先行隧道逆掘进方向的综合振速峰值总体持续衰减,而沿掘进方向,振速峰值上下波动,在一定范围内有升高的趋势;(4)不同步序下后行隧道结构的振速峰值出现在左拱腰、左侧仰拱和右拱肩处,监测点振速最大值为5.387 cm·s^-1;(5)迎爆侧振速受净距影响敏感,而背爆侧振速峰值随净距变化不明显,变化幅度在2.5%以内;(6)同一净距条件下,先行隧道迎爆侧监测点X向的振动速度峰值最大,Y向次之,Z向最小;(7)隧道右边墙附近的结构固有频率可能处于14.25~18.0 Hz之间,结构对该频段的应力波响应敏感。

Based on the Longquanshan Tunnel in Chengdu, numerical simulation calculations are conducted using the equivalent load method to investigate the dynamic response characteristics of the existing tunnel structure under different excavation sequences and clearances. The main research conclusions are as follows: (1) Due to the lack of a free surface, the excavation sequence of the subsequent tunnel has the greatest impact on the lining structure, while the impact of blasting sequences 2 and 3 on the structure is relatively small. (2) Under different excavation sequences, the peak vibration velocity of the subsequent tunnel structure is mainly observed at the sidewall, arch crown, and springing positions on the blasting face, with a maximum monitored velocity of 5.665 cm·s^-1. (3) The comprehensive peak vibration velocity in the reverse excavation direction of the preceding tunnel generally decreases, while along the excavation direction, the peak vibration velocity shows a tendency to increase within a certain range. (4) Under different sequences, the peak vibration velocity of the subsequent tunnel structure occurs at the left arch crown, left side voussoirs, and right shoulder of the arch, with a maximum monitored velocity of 5.387 cm·s^-1. (5) The vibration velocity on the blasting face is sensitive to the clearance, while the peak vibration velocity on the opposite blasting face shows less significant changes with a variation within 2.5%. (6) Under the same clearance condition, the maximum vibration velocity in the X direction at the monitoring point on the blasting face of the preceding tunnel is the highest, followed by the Y direction, and the Z direction is the lowest. (7) The natural frequency of the structure near the right sidewall of the tunnel may be between 14.25 and 18.0 Hz, and the structure is sensitive to stress wave responses in this frequency range.