深埋异形盾构组装洞设计及变形分析

Design and Deformation Analysis of Deep-Buried Special-Shaped Shield Assembly Tunne

为解决山体内部大埋深、大直径盾构始发难题,提出两段式蘑菇形大断面盾构组装洞设计方案。通过数值模拟对蘑菇形组装洞在不同施工阶段的变形特征进行了探究。研究结果表明:拱顶最大变形发生于所在断面开挖阶段;洞室两侧朝向洞室的变形对上部结构向下变形的限制作用从拱顶向两侧有所减弱;拱脚水平变形呈现出先增大后减小,再增大后减小的趋势,且测点最大水平变形均发生在非所在断面开挖阶段;下断面开挖使得拱脚水平变形逐渐由背离洞室转变为朝向洞室;远离拱顶位置的水平变形受下断面开挖影响更显著;下断面水平变形方向为朝向洞室,且蘑菇头开挖对下断面测点先行位移有显著影响。

To solve the problem of large buried depth and large diameter shield launching inside the mountain,a design scheme of two-stage mushroom-shaped large section shield assembly tunnel was proposed.The deformation characteristics of the mushroom-shaped assembly tunnel in different construction stages were explored through numerical simulation.The research results show that the maximum deformation of the vault occurs in the excavation stage of the section.The limiting effect of the deformation towards the tunnel on both sides of the tunnel on the downward deformation of the superstructure is weakened from the vault to both sides.The horizontal deformation of arch foot increases first and then decreases,and then increases and then decreases.Also,the maximum horizontal deformation occurs in the non-section excavation stage.The excavation of the lower section makes the horizontal deformation of the arch foot gradually change from backwards the tunnel to towards the tunnel.The horizontal deformation away from the vault is more significantly affected by the excavation of the lower section.The horizontal deformation direction caused by the excavation of all steps in the lower section is towards the tunnel,and the excavation of mushroom head has a significant influence on the first displacement of the measuring points in the lower section.