Three-Dimensional Face Stability Analysis of Deep and Shallow Tunnels in Rock Masses

Abstract Face stability is a critical issue in the stability analysis of tunnels, especially in soft soils and crushed rock masses. In this paper, considering two three-dimensional collapse mechanisms, upper-bound solutions are presented for determining the face pressure of deep and shallow tunnels...

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Bibliographic Details
Published in:International journal of geomechanics 2021-10, Vol.21 (10)
Main Authors: Seghateh Mojtahedi, Alireza, Imani, Meysam, Fahimifar, Ahmad
Format: Article
Language:English
Subjects:
Centrifuges
Charts
Collapse
Density
Diameters
Dimensional stability
Mathematical models
Pressure
Rock masses
Rocks
Soft soils
Soil
Soil stability
Stability analysis
Technical Papers
Three dimensional analysis
Tunnels
Upper bounds
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Summary:Abstract Face stability is a critical issue in the stability analysis of tunnels, especially in soft soils and crushed rock masses. In this paper, considering two three-dimensional collapse mechanisms, upper-bound solutions are presented for determining the face pressure of deep and shallow tunnels excavated in rock masses. The Hoek–Brown failure criterion was considered for the rock mass surrounding the tunnel. The proposed upper-bound formulations were compared with three-dimensional finite-element simulations and also with centrifuge test results available in the literature. The obtained results showed that the face pressure decreases with increasing σci, mi, and geological strength index. Besides, increasing the tunnel diameter and the rock mass density led to an increase in the face pressure, where for larger tunnels, the effect of the density became more pronounced. Finally, some charts were presented to specify the range of applicability of the concepts of deep and shallow tunnels. The results obtained from these charts demonstrated that the reduction in the Hoek–Brown parameters of the rock mass results in spreading the collapse mechanism from the tunnel face to the ground surface.
ISSN:1532-3641
1943-5622
DOI:10.1061/(ASCE)GM.1943-5622.0002152