Finite element analysis of long-term surface settlement above a shallow tunnel in soft ground

Abstract The construction of a tunnel in soft ground generally induces short-term and long-term ground settlements above the tunnel. In this study, finite element analysis of surface settlement above a shallow tunnel in clay till was performed. Field observations were performed to monitor the ground settlements above the tunnel and pore pressure changes around the tunnel. Four cases were simulated to investigate the influences of soil creep and flow boundary on surface settlement above the tunnel. The predicted surface settlement and pore pressure change were compared with those from field observations. From this study, it was found that creep behavior of the clay till played an important role in quantifying the long-term settlements above the tunnel, and the primary lining used in the tunnel construction could be approximately simulated by permeable flow boundary at the tunnel periphery. In addition, the influence of concrete lining installation on the long-term surface settlement was discussed.

[1]  R. J. Fowell,et al.  EFFECTS OF DIFFERENT TUNNEL FACE ADVANCE EXCAVATION ON THE SETTLEMENT BY FEM , 2003 .

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

[3]  B. M. New,et al.  SETTLEMENTS ABOVE TUNNELS IN THE UNITED KINGDOM - THEIR MAGNITUDE AND PREDICTION , 1982 .

[4]  David M. Potts,et al.  Time-based two dimensional modelling of NATM tunnelling , 2002 .

[5]  David M. Potts,et al.  A numerical study of the effect of groundwater movement on long-term tunnel behaviour , 2002 .

[6]  D. Fredlund,et al.  Equations for the soil-water characteristic curve , 1994 .

[7]  Kenichi Soga,et al.  Modelling of long-term ground response to tunnelling under St James's Park, London , 2007 .

[8]  R. Peck.  Deep excavations and tunnelling in soft ground , 1969 .

[9]  J. C. Small,et al.  The analysis of finite elasto-plastic consolidation , 1979 .

[10]  Harianto Rahardjo,et al.  Coupled Three-dimensional Consolidation Theory of Unsaturated Porous Media , 1984 .

[11]  Poul V. Lade,et al.  Experimental Study of Drained Creep Behavior of Sand , 1998 .

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

[13]  Robert J. Mair,et al.  Tunnelling and geotechnics: new horizons , 2008 .

[14]  M. Biot.  General Theory of Three‐Dimensional Consolidation , 1941 .

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