Three-dimensional numerical simulation of mechanized twin stacked tunnels in soft ground

• Published in: Journal of Zhejiang University. A. Science Vol. 15; no. 11; pp. 896 - 913
• Main Authors: Do, Ngoc-Anh, Dias, Daniel, Oreste, Pierpaolo
• Format: Journal Article
• Language: English
• Published: Hangzhou Zhejiang University Press 2014
• Subjects: Civil Engineering; Classical and Continuum Physics; Computer programs; Computer simulation; Construction; Engineering; Excavation; Impact analysis; Industrial Chemistry/Chemical Engineering; Mathematical models; Mechanical Engineering; Three dimensional; Tunnels (transportation); 隧道支护; Tunnel support; Lining response; Surface settlement; 重叠隧道; Segmental tunnel lining; 段隧道衬砌; 3D modelling; 三维模型; 衬砌响应; Stacked tunnels; U451; 地面沉降
• ISSN: 1673-565X; 1862-1775
• DOI: 10.1631/jzus.A1400117

The increase in transportation in large cities has made it necessary to construct twin tunnels at shallow depths. As far as the parallel excavation of mechanized twin tunnels is concerned, most of the cases reported in previous studies have focused on the interactions between two horizontally driven tunnels. However, less work has been devoted to the interactions between tunnels stacked over each other. The numerical investigation performed in this study has made it possible to evaluate the influence of the construction process on two stacked tunnels, using the FLAC
3D
finite difference element software. The structural forces induced in each of the stacked tunnels and the displacements in the surrounding ground have been highlighted. The results of the numerical analysis indicate that new tunnel construction can have a great impact on an existing tunnel. The greatest impacts are observed when the upper tunnel is excavated first. The excavation of the upper tunnel generally leads to greater surface settlements than when the lower tunnel is excavated first. This study also shows that the normal forces induced in the lower tunnel are always greater than those developed in the upper tunnel. The normal displacements and the bending moments induced in the lower tunnel are usually smaller than those in the upper tunnel.