Design and Deformation Analysis of Deep-Buried Special-Shaped Shield Assembly Tunnel
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.
large diameter shieldassembly tunnel with mushroom shapenumerical simulationdeformation characteristics
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