Volume 24, Issue 4 (December 2001)
A New Technique for Simulation of Tunnel Excavation in a Centrifuge
A new technique is presented for the simulation in a centrifuge of the excavation and lining of a model tunnel. It involves the use of a polystyrene foam core that is placed tightly inside the tunnel lining and that can be dissolved using an organic solvent. This technique is an improvement over other contemporary methods of modeling tunnel construction, such as reduction of air pressure supporting the tunnel lining or gradually draining zinc chloride solution (or some other heavy liquid) from within the lining. The stiffness of the filled tunnel can, approximately, be made to simulate the parent soil. The stiffness of the lining is correctly left in place when the foam core has been dissolved. Since there is no air or fluid pressure involved, there is also no need to seal the ends of the tunnel segment. Results from the first few trials of this technique in a 2 m diameter drum centrifuge are presented. These results demonstrate the usefulness of the technique in modeling progressive collapse of a tunnel and show ample promise of its use in the modeling of the construction of a tunnel using the NATM (New Austrian Tunneling Method).