Application of Convergence–Confinement Method in Analysis of Shallow Non-circular Tunnels

Stress reduction factor, λ, is a dimensionless coefficient in two-dimensional (2D) analysis based on convergence confinement method (CCM) of tunnel which represents stress relaxation in the tunnel walls at different excavation steps. The aim of this paper is to look into the influencing factors on parameter λ around the tunnel walls using finite difference code in order to improve the accuracy of the CCM. For this purpose, four different ground types with various tunnel radii, depths and cross section shapes are considered. Finally, the 2D analysis using uniform and variable stress reduction factors determined in this paper is compared with the 3D analysis of the tunnel. The results of this study enhance our understanding of the role of geometrical and soil material parameters of tunnel on stress relaxation around tunnel walls. The tunnel depth, soil type and tunnel shape have great influence on λ. Variable stress reduction factor enables the convergence–confinement method to predict the realistic behavior of third dimension of the tunnel and can also be used as the best alternative to 3D models.

[1]  Lidija Zdravković,et al.  Finite element analysis in geotechnical engineering , 1999 .

[2]  C. Fairhurst,et al.  APPLICATION OF THE CONVERGENCE-CONFINEMENT METHOD OF TUNNEL DESIGN TO ROCK MASSES THAT SATISFY THE HOEK-BROWN FAILURE CRITERION , 2000 .

[3]  R. K. Rowe,et al.  AN ANALYSIS OF THREE-DIMENSIONAL GROUND MOVEMENTS: THE THUNDER BAY TUNNEL , 1991 .

[4]  Mohamed A. Meguid,et al.  Physical modeling of tunnels in soft ground: A review , 2008 .

[5]  P B Attewell,et al.  Ground movements caused by tunnelling in soil , 1978 .

[6]  Determination of ground reaction curve for hyperbolic soil model using the hodograph method , 2005 .

[7]  F. Corbetta,et al.  Contribution à la méthode convergence-confinement par le principe de la similitude , 1991 .

[8]  R. C. K. Wong,et al.  Performance Assessment of Tunnels in Cohesionless Soils , 1991 .

[9]  D. Potts,et al.  Finite Element Analysis in Geotechnical Engineering: Volume Two - Application , 1999 .

[10]  C. González-Nicieza,et al.  Influence of the depth and shape of a tunnel in the application of the convergence-confinement method , 2008 .

[11]  Li Jun,et al.  Experimental study on face instability of shield tunnel in sand , 2013 .

[12]  K. Y. Lo,et al.  Subsidence owing to tunnelling. I. Estimating the gap parameter , 1992 .

[13]  Charles Wang Wai Ng,et al.  Three-dimensional ground settlements and stress-transfer mechanisms due to open-face tunnelling , 2005 .

[14]  Kevin Hewison,et al.  Closing the circle? , 2004 .

[15]  Rasoul Sadeghiyan,et al.  Determination of longitudinal convergence profile considering effect of soil strength parameters , 2016 .

[16]  K Schikora,et al.  TWO-DIMENSIONAL CALCULATION MODEL IN TUNNELING - VERIFICATION BY MEASUREMENT RESULTS AND BY SPATIAL CALCULATION. PROCEEDINGS OF THE SIXTH INTERNATIONAL CONFERENCE ON NUMERICAL METHODS IN GEOMECHANICS, 11-15 APRIL 1988, INNSBRUCK, AUSTRIA. VOLUMES 1 - 3 , 1988 .

[17]  B Schmidt PREDICTION OF SETTLEMENTS DUE TO TUNNELING IN SOIL: THREE CASE HISTORIES , 1974 .

[18]  E. T. Brown,et al.  Ground Response Curves for Rock Tunnels , 1983 .

[19]  A. Guenot,et al.  Analysis of convergence behind the face of a tunnel : Tunnelling 82, proceedings of the 3rd international symposium, Brighton, 7–11 June 1982, P197–204. Publ London: IMM, 1982 , 1983 .

[20]  Pierpaolo Oreste,et al.  Analysis of structural interaction in tunnels using the covergence–confinement approach , 2003 .

[21]  Charles E. Augarde,et al.  Modelling tunnelling-induced settlement of masonry buildings , 2000 .

[22]  Ing.D. Peila,et al.  Axisymmetric analysis of ground reinforcing in tunnelling design , 1995 .

[23]  G Colombet,et al.  OUVRAGES SOUTERRAINS - CONCEPTION, REALISATION, ENTRETIEN , 1988 .

[24]  Mahdi Heidari,et al.  Ground reaction curve for tunnels with jet grouting umbrellas considering jet grouting hardening , 2015 .

[25]  G Lombardi DIMENSIONING OF TUNNEL LININGS WITH REGARD TO CONSTRUCTIONAL PROCEDURES , 1973 .

[26]  David M. Potts,et al.  Twin Tunnel Interaction: Surface and Subsurface Effects , 2001 .

[27]  Alan Graham Bloodworth,et al.  Three-dimensional analysis of tunnelling effects on structures to develop design methods , 2002 .

[28]  R. K. Rowe,et al.  A method of estimating surface settlement above tunnels constructed in soft ground , 1983 .

[29]  S. Bernat,et al.  SOIL-STRUCTURE INTERACTION IN SHIELD TUNNELLING IN SOFT SOIL , 1998 .

[30]  R. Ribacchi,et al.  Practical Estimate of Deformations and Stress Relief Factors for Deep Tunnels Supported by Shotcrete , 2005 .

[31]  D. Bernaud,et al.  The `NEW Implicit Method' for Tunnel Analysis , 1996 .

[32]  M. Panet Le calcul des tunnels par la méthode convergence-confinement , 1995 .

[33]  Charles Wang Wai Ng,et al.  A short course in soil-structure engineering of deep foundations, excavations and tunnels , 2004 .

[34]  N. Vlachopoulos,et al.  Appropriate Uses and Practical Limitations of 2D Numerical Analysis of Tunnels and Tunnel Support Response , 2014, Geotechnical and Geological Engineering.

[35]  Murat Karakus Appraising the methods accounting for 3D tunnelling effects in 2D plane strain FE analysis , 2007 .

[36]  Robert J. Mair,et al.  SUBSURFACE SETTLEMENT PROFILES ABOVE TUNNELS IN CLAYS , 1993 .