Abstract: In view of the problems in advanced detection of defective geological structures in tunnel, a geological tunnel model was established based on viscoelastic medium to simulate the seismic wave propagation in fault, weak interlayer, karst cave and other geological hazard body. The tunnel is surrounded by the excavation damaged zone. A practical observation system and the staggered grid finite-difference method were employed for the simulation. According to the wave field snapshots at different instants, the response of seismic record acquired from the corresponding forward modelling was researched. Result shows that the two-dimensional forward simulation based on viscoelastic medium can be achieved by using a staggered grid finite-difference algorithm and adding tunnel constraints. The wave field snapshots could clearly reflect the seismic wave propagation and transformation in different geological models. The seismic record reflects the seismic response characteristics of different models, and offers a theoretical basis for the seismic prediction of actual tunnels.

Key words: viscoelastic medium, tunnel seismic, staggered grid, excavation damaged zone, wave field simulation