Investigation on Deformation Mechanism of a Shield Tunnel Undercrossing an Existing Tunnel Using PLAXIS 3D

DOI

10.2991/978-94-6463-932-2_16How to use a DOI?

Keywords

shield tunneling undercrossing; tunnel deformation; deformation mechanism; PLAXIS 3D finite element analysis

Abstract

With the rapid development of transportation infrastructure in China, metro networks in major cities have become increasingly complex, inevitably leading to scenarios where new shield tunnels underpass existing operational tunnels at close proximity. The structural deformation control arising from such scenarios has become a critical challenge constraining engineering safety. In these projects, existing tunnels are often subjected to complex additional stresses due to construction disturbances from new tunnels and stress release in the rock-soil mass, with their deformation response directly impacting operational safety and structural durability. This study, based on a metro shield tunnel project in a soft soil area of a city, employs PLAXIS 3D finite element software to numerically simulate the scenario of a new 6m outer diameter shield tunnel orthogonally undercrossing an existing 6m outer diameter metro tunnel. The research analyzes the deformation patterns and underlying mechanisms of the existing tunnel during shield tunneling. The results indicate that under intense disturbance from shield tunneling, the initial stress equilibrium of the stratum beneath the existing tunnel is disrupted, causing vertical settlement of the soil. Consequently, the existing tunnel exhibits an overall downward displacement in its central section, approximating a Gaussian curve. In the early stage, transverse eccentric pressure in the existing tunnel is induced by asymmetric lateral earth pressure generated during shield advancement. In the later stage, transverse tensile deformation occurs due to stress release in the soil and the extrusion effect of tail grouting.

Copyright

© 2025 The Author(s)

Open Access

Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

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TY  - CONF
AU  - Jingshan Jiang
AU  - Zheng Fang
AU  - Feijie Zhan
AU  - Jinyu Wang
AU  - Yuhao Tang
AU  - Mengping Ji
PY  - 2025
DA  - 2025/12/22
TI  - Investigation on Deformation Mechanism of a Shield Tunnel Undercrossing an Existing Tunnel Using PLAXIS 3D
BT  - Proceedings of the 2025 2nd International Conference on Civil Engineering Structures and Concrete Materials (CESCM 2025)
PB  - Atlantis Press
SP  - 142
EP  - 151
SN  - 2352-5401
UR  - https://doi.org/10.2991/978-94-6463-932-2_16
DO  - 10.2991/978-94-6463-932-2_16
ID  - Jiang2025
ER  -