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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/5051
Title: Stability of long unsupported twin circular tunnels in soils
Authors: Sahoo J.P.
Kumar J.
Published in: Tunnelling and Underground Space Technology
Abstract: The stability of two long unsupported circular parallel tunnels aligned horizontally in fully cohesive and cohesive-frictional soils has been determined. An upper bound limit analysis in combination with finite elements and linear programming is employed to perform the analysis. For different clear spacing (S) between the tunnels, the stability of tunnels is expressed in terms of a non-dimensional stability number (?maxH/c); where H is tunnel cover, c refers to soil cohesion, and ?max is maximum unit weight of soil mass which the tunnels can bear without any collapse. The variation of the stability number with tunnels' spacing has been established for different combinations of H/. D, m and ?; where D refers to diameter of each tunnel, ? is the internal friction angle of soil and m accounts for the rate at which the cohesion increases linearly with depth. The stability number reduces continuously with a decrease in the spacing between the tunnels. The optimum spacing (Sopt) between the two tunnels required to eliminate the interference effect increases with (i) an increase in H/. D and (ii) a decrease in the values of both m and ?. The value of Sopt lies approximately in a range of 1.5. D-3.5. D with H/. D= 1 and 7. D-12. D with H/. D= 7. The results from the analysis compare reasonably well with the different solutions reported in literature. ¬© 2013 Elsevier Ltd.
Citation: Tunnelling and Underground Space Technology(2013), 38(): 326-335
URI: https://doi.org/10.1016/j.tust.2013.07.005
http://repository.iitr.ac.in/handle/123456789/5051
Issue Date: 2013
Keywords: Finite elements
Limit analysis
Optimization
Stability
Tunnels
Upper bound solution
ISSN: 8867798
Author Scopus IDs: 55171499200
7201861873
Author Affiliations: Sahoo, J.P., Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India
Kumar, J., Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India
Corresponding Author: Kumar, J.; Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India; email: jkumar@civil.iisc.ernet.in
Appears in Collections:Journal Publications [CE]

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