An automatic method for data processing of seismic data in tunneling

We present a new method for the prediction of the discontinuities and lithological variations ahead of the tunnel face. The automatic procedure is applied to data collected by seismic reflection surveys, with the sources and sensors located along the tunnel. The method allows: i) to estimate an average value of the wave velocity; ii) to detect the discontinuities for each source point; and iii) to analyze and plot the number of superposing estimates for each node of the domain. The final result can be interpreted as the probability to detect a discontinuity at a certain distance from the tunnel face. The method automatically estimates the peaks in the seismograms that can be related to a reflection. On the base of this process, the method only requires the source-receiver geometry and the data acquisition parameters. The procedure has been tested on synthetic and real data coming from a seismic survey on a tunnel under construction. The results indicate that the method runs very fast and it is reliable in the identification of lithological changes and discontinuities, up to more than 100 m ahead of the tunnel face. (C) 2013 Elsevier B.V. All rights reserved.