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基于南翔西路隧道下穿既有全三高速公路工程,采用FLAC3D数值分析手段对隧道三导洞开挖法施工过程中围岩应力场和位移场、初期支护内力分布情况、地表沉降情况进行了分析研究,得到了隧道施工完毕后,初期支护大管棚起着良好的支护效果,围岩应力集中区局限在拱部一定范围内。隧道三导洞法施工对拱部影响较大,各个分部开挖后周边围岩均有应力集中现象,但应力变化梯度不大。隧道临时支护拆除前地表沉降最大值23mm,临时支护拆除后地表沉降最大值45mm。隧道仰拱向上隆起30mm。隧道开挖后,隧道周边围岩位移不显著,满足规范要求。地表沉降最大值位置为隧道中线,对应地表沉降槽宽度为50m,影响范围为隧道中线左右各25m。初期支护拱部素混凝土安全系数满足施工安全要求。相关结论对类似工程的设计、研究具有一定的指导作用。
Based on the construction of Nanxiangxi Road Tunnel under the existing Quan-San Expressway project, the stress field and displacement field of surrounding rock during the construction of tunnel guide tunnel with three pilot tunnels, the initial internal force distribution and surface subsidence were analyzed by FLAC3D numerical analysis method Analysis and research, get the tunnel construction is completed, the initial support of a large pipe shed supporting a good effect, rock stress concentration area confined within a certain range of arch. The construction of tunnel three-guide tunnel method has a great influence on the arch section, and stress concentration is induced in the surrounding rock after excavation in all sections, but the gradient of stress variation is not large. The maximum surface settlement of the tunnel before the temporary support is 23mm, and the maximum of the surface settlement after the temporary support is removed is 45mm. Tunnel inverted arch uplift 30mm. After tunnel excavation, surrounding rock displacement around the tunnel is not significant, to meet the specifications. The maximum position of the surface subsidence is the tunnel centerline, corresponding to the width of the surface subsidence trench of 50m and the influence range of 25m around the midline of the tunnel. The initial support arch element concrete safety factor to meet the construction safety requirements. Relevant conclusions on a similar project design, research has a guiding role.