Dizhi lixue xuebao (Dec 2023)
The tunnel damage effects and implications of the coseismic rupture of the Menyuan MS 6.9 Earthquake in Qinghai, China
Abstract
On January 8, 2022, a magnitude 6.9 earthquake occurred in Menyuan County, Qinghai Province, causing severe deformation and damage to the Da Liang Tunnel of the Lanzhou–Xinjiang high-speed railway, which is the first railway tunnel project broken by strike-slip earthquake in China. Through comprehensive analysis of field investigation data, InSAR surface deformation data, and monitoring results from the track control network (CPⅢ), this study delves into the characteristics of deformation and damage caused by the coseismic rupture zone of the Menyuan MS 6.9 earthquake on the Daliang Tunnel. The results indicate that the Haiyuan Fault Zone's Lenglongling–Tuolaishan fault segment is the seismogenic fault for this earthquake, forming a coseismic surface rupture zone approximately 21.5 km long. The dominant deformation nature is left-lateral strike-slip, with a maximum left-lateral displacement of about 3.1 m. As the coseismic rupture zone intersects the Daliang Tunnel, it severely damages the tunnel structure, with the most intense deformation and damage concentrated within 60 m on either side of the central rupture zone. Comparing the observed tunnel deformation with the characteristics of coseismic surface rupture deformation, it is evident that the maximum vertical displacement across the fault zone in the tunnel area is approximately 91.6 cm, with a maximum left-lateral offset of about 2.88 m. The angle between the Lenglongling fault and the Daliang Tunnel is approximately 60°, and the calculated maximum left-lateral offset of the seismogenic fault is about 3.08 m. This indicates a close alignment between the maximum slip offset from coseismic surface rupture and the fault's maximum offset across the tunnel, suggesting that the tunnel structure struggles to resist significant coseismic deformations. The findings of this study can serve as a scientific reference for the planning, construction, and seismic damage prevention of railway projects crossing active fault zones.
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