【摘要】 新建翠华山隧道与既有线小峪隧道垂直净间距仅为8m,复线隧道钻爆施工将影响既有隧道的结构安全。为保证既有线的安全运营,本文采用ANSYS/LS-DYNA软件建立了隧道的有限元模型,数值分析了下穿铁路隧道爆破施工时隧道间水平距离L为-6m～19m时既有线的动力响应。结合既有线振动速度的实测数据,采用质点振速判据评估了下穿隧道爆破施工时既有线结构的安全性,保障了下穿隧道施工时既有隧道的运营安全。数值模拟结果分析表明:未出现新的自由面之前、爆破炸药量不变的情况下,两隧道水平间距L从19m减小到10m时,数值模拟所得峰值振速由10.5cm/s增大到12.0cm/s;出现新的自由面之后、爆破炸药量不变的情况下,两隧道水平间距L从10m变为5m时,数值模拟所得峰值振速由12.0cm/s减小到10.2cm/s,其后迅速衰减。因此,隧道爆破施工中可人为地创造自由面以降低爆破震动效应的危害。同时,既有线隧道迎爆面测点竖向振动速度较大,是爆破震动效应控制的薄弱部位,施工过程中应加强该部位的监控量测。更多还原

【Abstract】 The clear distance between the new tunnel Cuihuashan and the existing line Xiaoyu tunnel is only about 8m,and the excavating blast in double line tunnel will affect structural safety of existing tunnel.In order to ensure the operation safety of existing line,the finite element model is established by using ANSYS/LS-DYNA code and the blast-induced vibration responses of existing tunnel structure are numerically studied when the horizontal distance L of the two tunnels is from 19m to-6m.By combining the measured vibration velocity of existing tunnel,the criterion of particle vibration velocity is employed to evaluate the structure safety of existing tunnel,and thus guaranteeing the operation safety of existing tunnel.The numerical simulation results obtained indicate that,with the same charge weight and without the emergence of new free surface,the peak value of vibration velocity increases from 10.5cm/s to 12.0cm/s when the horizontal distance L of the tunnels decreases from 19m to 10m.After the emergence of new free surface,the peak value of vibration velocity reduces from 12.0cm/s to 10.2cm/s when the horizontal distance L decreases from 10m to 5m,and then declines rapidly.Therefore,the free surface could be created artificially so as to reduce the damage of blast-induced vibration in practical engineering.Meanwhile,the vertical vibration velocity at the side wall of existing tunnel toward the blasting is higher,and the tunnel wall facing the blasting side is a weak part for controlling blast-induced vibration effects,so monitoring and measurement of the weak part should be strengthened during the tunnel construction process.更多还原