Case study on shield steering along a sharp curve

Abstract

Due to ongoing development of shield tunnelling technologies, usage of more complicated tunnel alignments is increasing. Therefore, more proper steering of shield machines is expected. Shield behaviour is controlled mainly by copy cutter, articulation mechanism, and jack force, but these three shield steering parameters are not easy to be determined, because of their high co-linearity and varying geological conditions. A discharging tunnel with a sharp curve was planned by an articulated EPB type shield. Therefore, as a preliminary analysis, the required shield steering parameters for the planned tunnel were calculated by shield behaviour simulation, and the obtained shield steering parameters were compared with the shield equipped capacity. Furthermore, as a post-analysis, the shield behaviour simulation was carried out by using the site measured data, and the input parameters at the preliminary analysis were examined. Through this research, the followings were found: 1) in the preliminary analysis, the shield equipped capacity is enough to construct the tunnel; 2) in the post-analysis, it was required to increase the face resistance parameter and to decrease the effective rates of overcut and copy cutter length, to match the analysis shield behaviour to the measured one; and 3) the shield kinematic model can simulate shield behaviour reasonably.