Effect of underground tunnel on the ground surface acceleration

• The study investigates an underground tunnel effect on ground surface acceleration.
• Centrifuge tests, conducted in KAIST, were used to verify numerical modeling.
• The tunnel amplifies long periods and deamplifies short periods of input motion.
• Tunnel could have either positive or negative effect on the acceleration response.
• Effect of the tunnel on the ground surface acceleration can be considerable.

A series of dynamic centrifuge tests was designed and conducted to study the seismic behavior of buried box tunnels. In this study, numerical simulations of the same tests were also performed using a finite difference software. The simulation results were in very good agreement with the results observed in the centrifuge tests. Subsequently, verified numerical model was used to perform parametric studies on the effect of an underground box tunnel on the ground surface acceleration. The results of parametric studies revealed that an underground tunnel could have either positive or negative effect on the ground surface acceleration. Presence of the tunnel amplifies long periods and deamplifies short periods of the motion. Therefore, it is concluded that the effect of an underground structure on the acceleration at the ground surface may be significant and hence, should be taken into account for seismic zonation of urban areas.