Seismic energy response and damage evolution of tunnel lining structures

Abstract

Although tunnels typically experience a lower rate of damage than surface structures during an earthquake, some tunnels have experienced considerable damage during recent strong earthquakes. Hence, seismic response analysis of tunnels located in high-intensity earthquake zones is an important issue for tunnel engineers. In this study, a three-dimensional numerical model of a tunnel was developed to analyse the dynamic energy response and damage evolution of tunnel linings under the influence of seismic waves. A nonlinear concrete damage model for the tunnel lining and a special infinite element boundary technique were employed to investigate the damage pattern and damage evolution process for tunnel lining structures. In addition, the concept of seismic layer is proposed on the basis of the flexibility ratio (a measure of the flexural stiffness of a tunnel relative to the surrounding ground) as a countermeasure against seismic damage. Subsequently, numerical simulation results are compared with field observation data for tunnels damaged during the Wenchuan earthquake. The crack patterns revealed in the damage analysis of the numerical model have also been observed in the field investigation of several mountain tunnels damaged during the Wenchuan earthquake. The similarities between the damage patterns of the lining structures in the field observation and in the damage analysis provide additional evidence of the considerable influence of seismic waves on the damage patterns.