Seismic Performance of a Concrete Highway Tunnel under Earthquake Sequence Using a Concrete Damage Plasticity Model

Abstract

The aim of this paper was to investigate the dynamic response of a concrete tunnel subjected to mainshock–aftershock seismic sequence. Three components of the registered seismic saquence were applied as seismic excitation acting in three directions. A three-dimensional FE model of a tunnel section (600 m long) was prepared with the ABAQUS software. The soil layers interacting with the tunnel lining were also taken into consideration. To represent the inelastic behavior of the concrete material under the earthquakes, a concrete damage plasticity model (CDP) was assumed a constitutive model for the concrete. The analysis proved that strongly nonlinear behaviour of the concrete lining of the tunnel was observed under the sequence of seismic events. The plastic strains as well the tensile damage (cracking) were noticed in some zones of the concrete lining after the first and the second event. The crack patterns were in good agreement with damages observed on concrete tunnels during real earthquakes. The results indicate that aftershocks can enlarge zones affected by irreversible strains or cause damage evolution. The analysis also revealed that aftershocks, even being much weaker than main events, may result in additional loss of concrete material strength while performing in mainshock-aftershock seismic sequences and striking a structure which is already degraded by a mainshock.