Realistic FD modeling of the tunnel environment for seismic tomography

To improve the safety both of the tunnel constructions and buildings at the surface, seismic tomography methods can be used to detect possible safety threads behind the tunnel wall (e.g. cavities, water bearing zones, fractures). Basis for such a tomography is a profound understanding of the seismic wave propagation in the complex surrounding of a tunnel which can be gained from seismic modeling We, therefore, created a realistic tunnel model that accounts for typical features encountered during tunnel construction, e.g. heterogeneous host rock, excavation damaged zone (EDZ) and topography of the tunnel wall. This model is used for the 3-D elastic wave field simulations. Data from multiple shot positions will be later on used for a seismic tomography, either by standard travel time tomography or full waveform tomography. Main objective is the accurate seismic modeling using optimal discretization parameters and an implicit free surface boundary with topography.