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岩体内部的初始应力及隧道开挖后的围岩应力是隧道工程的关键影响因素,为了更全面地了解不同应力场软弱围岩公路隧道施工的力学特征,建立有效的有限元模型,采用不同加载方式,模拟不同应力场,对软弱围岩公路隧道施工过程中隧道围岩位移和应力变化特征及其影响范围进行了详细分析,并对衬砌结构的受力特征进行深入研究。结果表明:不同应力场决定了隧道施工过程中围岩塑性区的大小和位置,这也就决定了隧道施工中重点监控的位置;在不同应力场隧道开挖完成后,拱上20 m水平面围岩竖向位移、拱上中心线围岩竖向位移及仰拱底围岩竖向位移随着侧压力系数的减小而明显增大,拱腰处围岩水平位移则随着侧压力系数的减小而明显减小;应力场对衬砌结构的内力影响很大。
Initial stress in rock mass and surrounding rock stress after tunnel excavation are the key influencing factors in tunnel engineering. In order to know more about the mechanical characteristics of tunnel construction in soft surrounding rock with different stress field, an effective finite element model Loading mode and simulating different stress field. The displacement and stress variation characteristics of tunnel surrounding rock during the construction of soft surrounding rock road tunnel are analyzed in detail and their influence range is analyzed in detail. And the stress characteristics of lining structure are studied deeply. The results show that different stress fields determine the size and location of the plastic zone in the surrounding rock during tunnel construction, which determines the location of the key monitoring in the tunnel construction. After the excavation of different stress fields is completed, The vertical displacement of rock, the vertical displacement of surrounding rock on the center line and the vertical displacement of surrounding rock at the bottom of inverted arch increase obviously with the decrease of lateral pressure coefficient, while the horizontal displacement of surrounding rock at arch waist increases with the lateral pressure coefficient Decreases obviously and reduces obviously; The stress field has a great influence on the internal force of the lining structure.