Volume 5, No. 1, 2011
Received: 2010/12/12, Accepted:
Authors:
A. A. Elsayed Elsayed;
Abstract:
Finite element technique is used to model two phases of tunneling process, namely; excavation and rocklining
interaction. The excavation phase is responsible for determining the pre-lining rock mass deformations
and the reduced in-situ stresses. The interaction phase models the compatibility of the rock-lining system. The
deformations and stresses of the rock-lining system and the final rock mass pressure acting on the lining are
determined. The finite element results are compared with the results of the Convergence-Confinement
method for the case study (Shimizu Tunnel) that was guided by field measurements.
One of the main objectives of this study is to investigate the effect of different parameters on the behavior of
excavated tunnel before and after lining activation. The analysis followed the same procedure which had been
applied in the analysis of the case of Shimizu Tunnel taking into consideration the different values of the
tunnel radius and the depth of excavated tunnel through different qualities of rock ranging between poor,
moderate and hard rock. The parametric study has been conducted for circular tunnel.
The first lining system involved in this study was assumed to be shotcrete of thicknesses of 20, 30, 40 and
50cm, and the second lining system was steel ribs with shotcrete of thicknesses of 20, 30, 40 and 50cm. The
results of Finite Element Analysis were presented for different thicknesses.
Keywords:
Convergence-confinement approach, Rock tunnels, Ground reaction curve, Shotcrete, Support characteristics curve, Lining system