Development of a Foundational Numerical Analysis Model for Evaluating the Dynamic Behavior of Excavated Tunnels
Development of a Foundational Numerical Analysis Model for Evaluating the Dynamic Behavior of Excavated Tunnels
OpenSees is an open-source finite element analysis program specialized for soil-structure interaction and seismic dynamic analysis. In this study, a numerical model for an excavated tunnel was developed using OpenSees, and dynamic analyses were conducted under various conditions to evaluate both ground acceleration and tunnel moment responses. The ground conditions were classified according to rock stiffness into hard rock, soft rock, weathered rock, and fault zone. The structure depth was set at 15m, and analyses were performed for a total of four cases. For input ground motions, 20 domestic and international recorded earthquakes were applied, scaled by factors of 1.0, 1.5, and 2.0. The dynamic analysis results indicated that the acceleration response showed an increasing trend as rock stiffness decreased; however, the amplification relative to the input ground motion was minimal. The maximum bending moment response showed a clear increasing trend as stiffness decreased. In particular, within Fault zones characterized by low stiffness, the seismic response moments induced in the tunnel lining exceeded the allowable bending capacity across all three earthquake scenarios. This suggests that, in contrast to the inherent safety typically associated with competent rock masses, Fault zones with significant stiffness contrast trigger stress concentrations that transcend the structural limits of the lining. Consequently, it is imperative to prioritize rigorous geological characterization and site-specific seismic risk assessments that incorporate the unique dynamic properties of these vulnerable geological formations.
Dongha Baek; Mintaek Yoo; Seokjung Kim; Jeongjun Park; Il-Wha Lee
11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)
Special Session 5: Combination of numerical and physical modelling
https://doi.org/10.53243/ICPMG2026-334