交叉隧道不同接近度对既有隧道稳定性的影响研究

Research on Influence of Different Proximities of Cross Tunnels on Stability of Existing Tunnels

以隧道位移及衬砌应力增量为控制标准,通过建立不同净距的正交下穿数值模型,分析新建隧道不同净距(0.25D、0. 5D、0.75D、1.0D、1.25D)正交下穿施工对既有隧道的位移及应力增量变化,判断既有隧道结构的稳定性,结果表明:不同净距下穿过程中对既有隧道的影响范围基本一致,主要集中在新建隧道中线左右20m,最大竖向沉降随着净距的增大呈现先增大达峰值后减小的趋势,采用经典高斯曲线拟合得出经验沉降槽宽度系数;下穿施工过程中既有隧道的横向应力增量先为压应力增量,最终表现为压应力增量,纵向应力增量始终为压应力增量,随着两隧道净距的减小,拉压应力增量增大,通过拟合得出应力增量与隧道净距的变化关系,合理预测不同净距下既有隧道的应力变化。

Based on the control standard of tunnel displacement and stress increment of lining,the changes of displacement and stress increment of existing tunnels during the orthogonal underpass construction with different clear distances (0.25D,0.5D,0.75D,1.0D,1.25D) are analyzed through establishing the numerical model of orthogonal underpass with different clear distances,and the stability of existing tunnel structure is judged.The results show that:the influence scope of the existing tunnel is basically the same during the underpass procedure with different clear distances,mainly concentrating on about 20m of the middle line of the newly built tunnel.The maximum vertical settlement first increases to the peak value and then decreases with the increase of the clear distance.The empirical settlement slot width coefficient is obtained by classical Gauss curve fitting.The transverse stress increment of the existing tunnel in the underpass construction is firstly compressive stress increment,and finally compressive stress increment.The longitudinal stress increment is always the compressive stress increment.With the decrease of the clear distance between the two tunnels,the increment of tension and compression stress increases.The relationship between the stress increment and the clear distance of the tunnel is obtained by fitting,and the stress changes of the existing tunnels under different clear distances are reasonably predicted.