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隧道附近的路堑爆破开挖会由于土体卸荷和巨大的爆破峰值压力作用使得既有隧道处于受力复杂的偏压状态,影响隧道结构的稳定和安全。为研究路堑开挖对既有隧道的影响,以福建金鸡山隧道为依托,将路堑爆破的峰值压力等效换算为均布压力以便运用Midas-nx软件进行数值模拟,对比分析出不同施工阶段、不同隧道截面、同一隧道截面不同测点位置的衬砌受力和变形规律。结果表明,当开挖路堑边坡与隧道衬砌的距离小于30m时,路堑爆破开挖对既有隧道的影响较大;衬砌受力和变形明显增长,爆破时的衬砌应力是爆破前10倍以上,长期的爆破荷载将使得衬砌变形量增加到5倍以上;路堑开挖使隧道衬砌的受力和变形出现严重的偏压特性。
Due to the unloading of soil mass and the huge blasting peak pressure, the existing tunnels are subjected to complicated biasing conditions and affect the stability and safety of tunnel structures. In order to study the influence of cutting excavation on the existing tunnels and based on the tunnel of Fujian Jinji Mountain, the peak pressure of cutting blasting is equivalently converted into uniform pressure for numerical simulation by using Midas-nx software. Comparing different construction stages, Different tunnel cross section, the same tunnel cross section of different measuring points of the lining force and deformation law. The results show that when the distance between excavation cutting slope and tunnel lining is less than 30m, the influence of cutting blasting excavation on the existing tunnel is greater; the stress and deformation of lining increase obviously, and the lining stress during blasting is more than 10 times before blasting , Long-term blasting load will make lining deformation increase more than 5 times; excavation of tunnel so that the tunnel lining stress and deformation appear serious bias characteristics.