Effects of tunnelling on existing support systems of perpendicularly crossing tunnels

Liu, H. Y., Small, J. C., Carter, J. P. and Williams, D. J. (2009) Effects of tunnelling on existing support systems of perpendicularly crossing tunnels. Computers and Geotechnics, 36 5: 880-894. doi:10.1016/j.compgeo.2009.01.013


Author Liu, H. Y.
Small, J. C.
Carter, J. P.
Williams, D. J.
Title Effects of tunnelling on existing support systems of perpendicularly crossing tunnels
Journal name Computers and Geotechnics   Check publisher's open access policy
ISSN 0266-352X
1873-7633
Publication date 2009-06
Year available 2009
Sub-type Article (original research)
DOI 10.1016/j.compgeo.2009.01.013
Volume 36
Issue 5
Start page 880
End page 894
Total pages 15
Editor Gyan N Pande
Scott W Sloan
Stan Pietruszczak
Place of publication Oxford, U.K.
Publisher Elsevier Sci
Collection year 2010
Language eng
Subject C1
090501 Civil Geotechnical Engineering
870401 Civil Construction Processes
Abstract The interactions between perpendicularly crossing tunnels in the Sydney region are investigated using a full three-dimensional (3D) finite element analysis coupled with elasto-plastic material models. Special attention is paid to the effect of subsequent tunnelling on the support system, i.e. the shotcrete lining and rock bolts, of the existing tunnel. The results of the analysis show that in a region such as Sydney. with relatively high horizontal stresses, installation of the new tunnel causes the shotcrete lining of the existing tunnel to be in tension in the side facing towards the tunnel opening and in compression at the crown and invert. The pre-stressed rock bolts are usually tensioned more in the sections closest to the tunnel opening. For this particular study, if a new tunnel is driven perpendicularly beneath an existing tunnel, significant increases are induced in the bending moments in the shotcrete lining at the lateral sides of the existing tunnel and in the axial forces at its crown and invert. The increase in side bending moments causes further tensile cracking but the crown and invert stresses remain within the thresholds for both compressive failure and tensile cracking for shotcrete lining of typical concrete quality. Moreover, the driving of the new tunnel causes the tensile forces in the existing side rock bolts to increase and those in the existing crown rock bolts to decrease. In contrast, if the new tunnel is driven perpendicularly above the existing tunnel, compressive failure of the existing shotcrete lining is induced at the crown of the deeper tunnel for concrete of typical capacity and a significant tensile force increase of the existing rock bolts around the crown. It is concluded that in order to ensure the stability of the existing tunnel, local thickening is needed at the sides of the existing shotcrete lining if the shallow tunnel is installed first and local thickening is needed at the crown if the deep tunnel is installed first.
Keyword Tunnel interaction
Perpendicular tunnels
Crossing tunnels
Tunnelling
Finite element modelling
Support systems
Shotcrete lining
Rock Bolts
Q-Index Code C1
Q-Index Status Confirmed Code

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2010 Higher Education Research Data Collection
School of Civil Engineering Publications
 
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Created: Thu, 03 Sep 2009, 08:07:19 EST by Mr Andrew Martlew on behalf of School of Civil Engineering