ABSTRACT
The present paper proposes an accurate imaging technique for looking ahead of the tunnel face using three-component geophones with tunnel blasting and Tunnel Boring Machine (TBM) vibrations as seismic sources. The procedure for the technique is as follows:
Record the seismic signals from the reflectors ahead of the tunnel face using three-component receivers set on the tunnel walls;
Detect the directions of incidence of the reflected waves; and
By weighing according to the directions of incidence of the reflected waves, make images of the reflector plane using an equi-travel time plane.
The proposed technique is applied herein to data sets collected at an actual drilling operation site, and the results are found to agree with the geological observations of the walls after the drilling of the tunnel.
