Damages of highway tunnels during 2022 Luding earthquake (Mw=6.6)

On 5 September 2022, an Mw = 6.6 earthquake hit the Luding area, Sichuan Province, China, leading to 93 deaths, 25 disappearances, and great economic loss. The earthquake caused a series of geologic hazards and severe damage to infrastructures, such as tunnels, bridges, houses, and roads. In this study, a field survey was conducted for the twin tunnels along the Luding-Shimian highway after the earthquake. The highway was close to the epicenter, which was built along the Daduhe fault. Comprehensive data on tunnels along the highway, such as damage characteristics, geological conditions, conditions behind the tunnels, and design documents, were collected. The field investigation found that three tunnels were damaged due to seismic shaking. Tunnel damage, such as cracks, spalling, and leakage, was observed. Based on the compiled data, a preliminary analysis was performed for the possible mechanisms of damage to the tunnels. The damage was related to the old landslide mass, fractured zone, invert setup, and direction of tunnel alignment.