Twin Tunnels Stability Factors Fc, Fs and Fγ

Shiau, Jim ORCID: and Al-Asadi, Fadhil (2021) Twin Tunnels Stability Factors Fc, Fs and Fγ. Geotechnical and Geological Engineering: an international journal, 39 (1). pp. 1-11. ISSN 0960-3182


This paper uses tunnel stability factors to estimate the minimum supporting pressure required to maintain the stability of twin circular tunnels drive side-by-side in drained cohesive-frictional soil. Similar to the bearing capacity equation proposed by Terzaghi, the proposed method is based on the three stability factors (Fc, Fs and Fγ) that are functions of the soil internal friction angle and the tunnel depth ratio. Unlike the case of a single tunnel, the centre-to-centre distance between the tunnels appears as a new parameter that must be considered in twin tunnel stability. For various spacing ratios (S/D) between the tunnels, non-dimensional tunnel stability factors (Fc, Fs and Fγ) are established for various depth ratios (C/D) and soil internal friction angles (Ø) using two-dimensional finite element limit analysis. For practical suitability, the results are presented in the form of dimensionless stability charts with the actual tunnel stability factors closely bracketed from above and below using upper and lower bound methods. As an extra validation, the results are compared with available solutions reported in the literature.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Date Deposited: 20 Aug 2020 04:17
Last Modified: 13 May 2021 01:58
Uncontrolled Keywords: Upper bound; Lower bound; Finite element limit analysis; Tunnel stability factors Spacing ratio
Fields of Research (2008): 09 Engineering > 0905 Civil Engineering > 090501 Civil Geotechnical Engineering
Fields of Research (2020): 40 ENGINEERING > 4005 Civil engineering > 400502 Civil geotechnical engineering
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
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