1. Twin Tunnels Stability Factors Fc, Fs and Fγ.
- Author
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Shiau, Jim and Al-Asadi, Fadhil
- Subjects
TUNNELS ,BEARING capacity of soils ,INTERNAL friction ,FINITE element method - Abstract
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 (F
c , 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. [ABSTRACT FROM AUTHOR]- Published
- 2021
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