Transverse Dynamic Response of Circular Tunnel Excavation in Blocky Rock Mass using Distinct Element Method

Abstract

Recent cases of damage to mountain tunnels have raised concerns about the seismic performance of underground structures. The damaged sections have been majorly observed in highly fractured and weathered geological regions. The literature suggests that the interaction of the stress waves with the discontinuous medium may considerably influence the behavior of tunnel excavations. However, most of the investigations toward the evaluation of the transverse dynamic response of tunnels idealize the geological medium as a continuum medium, failing to capture the interaction between the stress waves and joints. To overcome the limitation, the present study attempted to assess the dynamic behavior of a lined circular tunnel passing through a blocky discontinuous rock mass using the Voronoi tessellation scheme in a distinct element framework. The influence of frequency of input motion, tunnel depth, in situ stress ratio, and types of seismic waves was studied with regard to the dynamic forces that developed in the liner. Moreover, the results, presented in terms of incremental dynamic forces along the tunnel liner, were utilized to corroborate past damages reported in the literature.