Taking the new-built Line 3 metro under-passing the existing metro Line 4 in Shenzhen as the engineering background, numerical simulation was adopted to analyze the interactive dynamic responses between the new-built metro tunnel by blasting construction and the existing operation metro tunnel. The results indicate that under the action of blasting vibration the maximum tensile stress, the maximum vertical displacement and the maximum vibration velocity of the secondary lining for the existing metro tunnel are all located in the center of inverted arch. The maximum vertical displacement and the maximum vibration velocity at the inverted arch, arch foot, side wall and arch crown are successively reduced. The vibration velocity at the center of the inverted arch is beyond the blasting safety control standard when the excavation footage is 1 m. Accordingly, the vibration velocity of the secondary lining for the existing metro tunnel should be intensively monitored during construction. Just to be on the safe side, the excavation footage is suggested to be 0. 5 m. The maximum displacement, the maximum additional moment and the maximum additional axial force produced by the existing metro operation on the new-built tunnel is 0. 22 mm, 750 N ? m and 30 kN respectively. It indicates that the existing metro operation has little impact on the new-built tunnel and that can be ignored in the design and construction of new metro tunnel.%以深圳新建地铁3号线下穿既有地铁4号线为工程背景,采用数值分析方法,对爆破施工新建地铁隧道与既有运营地铁的相互动力响应进行模拟分析.结果表明:在爆破振动作用下,既有地铁隧道二衬的最大拉应力、最大竖向位移和最大振速均位于仰拱中心处,仰拱、拱脚、边墙及拱顶位置处的最大竖向位移和最大振速依次减少；开挖进尺为1m时,仰拱中心振速超过了爆破安全控制标准,因此在施工中应对既有地铁隧道二衬的振速进行重点监测,为安全计,建议将开挖进尺设计为0.5m；既有地铁运营对新建地铁隧道产生的最大位移为0.22 mm,最大附加弯矩为750 N·rn,最大附加轴力为30 kN,说明既有地铁运营对新建地铁隧道的影响较小,在新建地铁隧道设计和施工时可以不予考虑.
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