ABSTRACT
Site inspection of the tunnels was carried out after the Duzce earthquake. The damage patterns discovered are summarized below.
3.1 Relevant site observations
The epicentre of the Mw 7.2 earthquake was approximately 20 km (Erdik 2001) from Asarsu portals of the tunnels. The surface rupture of the fault was within 3 km of these portals. Peak acceleration and velocity recorded at the nearest strong motion station at Bolu were 0.81 g and 66 cm/s, respectively. It was initially concluded that this damage was due to ground shaking alone since no surface ruptures had been observed to cross the tunnel alignment and no fault offset displacements were evident within the accessible parts of the tunnels. In the main Asarsu tunnels within the metasediments, slight-moderate damage was observed as slabbing and spalling of shotcrete, and also longitudinal cracking and deformation of the potentially weak Top Heading-Bench joint.
