DEM Simulations of the Seismic Response of Tunnels Embedded in Granular Deposits

The study examines the seismic response of tunnels constructed in a layer of cohesionless soil of depths more than 20 m. The soil assembly and tunnel lining were modeled using three-dimensional discrete-element method (DEM) simulations. Soil particles were modeled as rigid spherical particles that may overlap at contact locations. The tunnel lining was modeled as a flexible structure composed of particles bonded together with cementitious bonds to mimic the physical features of a real tunnel. Free-field boundaries were utilized at the model's lateral sides to prevent the propagating wave's reflections back to the domain and employ the free-field motion. The DEM computational framework was validated using published centrifuge test results, and the numerical simulation results reveal good agreement with the experimental test results when subjected to the same input motion.