Prediction of the change in ground condition ahead of tunnel face using 3-dimensional displacement monitoring

摘要

One of the common problems in tunnelling is roof fall or face collapse caused by sudden change in ground condition. During the excavation of a tunnel, this change in ground condition or the existence of weak zones behind the tunnel face has to be identified as early as possible so that proper change in excavation method or support design can be made accordingly. Horizontal pilot boring at the tunnel face is one solution, but it is rather expensive and time consuming. Tunnel Seismic Prospecting campaign (TSP) is a better solution, but it is still expensive.