整体式中隔墙连拱隧道模型试验及现场监测

针对连拱隧道复杂的施工力学特性，结合实际工程，通过模型试验和现场监测分别研究了整体式中隔墙连拱隧道在中导正洞台阶法施工过程中的位移和中隔墙应力变化情况，并详细分析了各开挖步骤对其的影响。结果表明，对于整体式中隔墙连拱隧道，上台阶开挖对顶部位移和中隔墙应力的影响大于下台阶开挖产生的影响；隧道顶点位移-历时曲线总体形状呈S形，最大位移发生在后掘隧道的顶部。由于主洞的开挖将使中隔墙另一侧应力增加较大，而本侧应力增加较小甚至降低，因此，先掘隧道的开挖使中隔墙产生由先掘隧道侧向后掘隧道侧偏转的弯矩，而后掘隧道的开挖将使该弯矩值减小

Model test and in-situ monitoring of double-arch tunnel with integrated middle wall

In order to study the complex characteristics of double-arch tunnel during excavation,model and in-situ monitoring based on a double-arch tunnel with integrated middle wall are conducted to study the displacement and the stress of middle wall during excavation by bench cut method with middle drift.The effect of each excavation stages is analyzed in detail.The test results show that the displacement and stress are effected more significantly by the excavation of calotte than by the excavation of bench.The displacement-time curve is in a shape of S and the maximum displacement locates at the top of later excavated tunnel.Because the excavation of tunnel makes the stress in the other side of middle wall increase greatly and the stress in the excavation’s side increase slightly or decrease,the bending moment in middle wall is induced with the direction from the earlier constructed tunnel to the other by the excavation of earlier excavated tunnel and decreases with the excavation of later excavated tunnel.