ABSTRACT
Accurate prediction of the geological conditions ahead of the tunnel face is essential for safe and economical tunnel construction. As an application of the drill logging, a new method for predicting the distribution of seismic velocity ahead of the tunnel face has been developed. The method makes it possible to determine the travel-time from transmission to reception by determining the transmission time at which the rock is hit by the drill bit and processing the wave form of the vibration received by the receivers on the tunnel face. Field test results have shown that the newly developed method is useful in predicting the seismic wave velocity distribution ahead of the tunnel face.
