Abstract:

Seismic measurements during tunnel operations aim at images of maximum spatial resolution. However, there are still principal limitations of the method applied in tunnels with regard to the spatial resolution by the signal frequency and attenuation,  the signal frequency and attenuation, and the smallan gular illumination coverage. A finitedifference simulation of elastic wave propagation was performed to compute a synthetic tunnel seismic reflection   survey. Synthetic data were used for optimizing the best practice tunnel data processing sequence for both P and S  waves, especially for the use of attenuation models to compensate amplitude loss as well as dispersion by an inverse Qfiltering, and for the use of a spatially variable velocity model to yield the right image positionof a reflecting geological element in space. The transfer and capability of this practice to real tunnel application was finally demonstrated by the case study of the tunnel seismic prediction method in the Koralm tunnel project in Austria.

Key words: tunnel; seismic imaging; finitedifference; resoluti on; prediction