Rehabilitation activities for the railway tunnel damaged during the february 6TH kahramanmaraş earthquakes

This study examines the damages sustained by the T3 Tunnel on the Malatya-Narlı conventional railway line, intersected by the earthquake surface rupture, following the Kahramanmaraş centered earthquakes on February 6, 2023 (Pazarcık Mw:7.7; Elbistan Mw:7.6) and presents the rehabilitation works carried out to reopen the railway tunnel to transportation. The T3 Tunnel, constructed in 1933 with a key stone masonry lining structure, is located in Ozan Village, Gölbaşı District, Adıyaman Province. The T3 Tunnel, which was intersected by the Erkenek Fault, one of the segments of the East Anatolian Fault Zone (EAFZ), experienced landslides during the earthquakes. Deformations occurred within the tunnel, which was both intersected by the fault and subjected to landslide triggers, and a collapse occurred inside the tunnel. Detailed in-situ observation studies, detailed geophysical surveys, geological and geotechnical investigations were conducted to determine the nature of the failure. Based on the geological data obtained from these studies, the necessary works and construction methodologies required for rehabilitating and restoring the tunnel to operational status were identified. A two stage design was developed, including from inside the tunnel and above the tunnel. Primarily, it was aimed to prevent the landslides that occurred and continued to move above the tunnel. Subsequently, it was aimed to strengthen the ground and portal area where the collapse occurred by performing consolidation grouting above the tunnel. Following these measures, a new portal structure was designed, excavation and support works were planned to facilitate passage through the collapsed section. The design was implemented on-site in accordance with the determined construction stages and was completed without any problems in a period of 6 months, despite the ongoing aftershocks.