Stability analysis of twin circular tunnels using shear strength reduction method

Shiau, J. ORCID: https://orcid.org/0000-0002-9220-3184 and Al-Asadi, F. (2020) Stability analysis of twin circular tunnels using shear strength reduction method. Geotechnique Letters, 10 (2). pp. 1-9. ISSN 2049-825X


Abstract

This paper investigates the face stability of twin circular tunnels horizontally aligned in cohesive undrained soil under plane strain conditions. The shear strength reduction method in the two-dimensional finite-element limit analysis programme is used to obtain rigorous upper and lower bounds of the factor of safety (FoS) for various depth ratios (C/D) and centre-to-centre spacing ratios (S/D) between the tunnels. Since the undrained shear strength is not a function of the mean normal stress, stability results are independent of loading directions. Therefore, the stability (in collapse or blowout) for this problem is well expressed by using Broms and Bennermarks’ original stability number N = (σs + γH − σt)/Su. The variations of the FoS have been presented for different combinations of stability numbers (N) and geometries (C/D and S/D). The FoS and the stability number results are compared and validated by using the finite-difference method as well as other existing solutions available in the literature. The results from this study are summarised in stability charts for use by designers and practising engineers.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 July 2013 -)
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 July 2013 -)
Date Deposited: 09 Jun 2020 04:45
Last Modified: 11 Jun 2020 03:52
Uncontrolled Keywords: numerical modelling; limit state design/analysis; tunnels and tunnelling
Fields of Research : 09 Engineering > 0905 Civil Engineering > 090501 Civil Geotechnical Engineering
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
Identification Number or DOI: 10.1680/jgele.19.00003
URI: http://eprints.usq.edu.au/id/eprint/38597

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