By September 2021, rail transit systems had been operational in 49 Chinese cities, with a cumulative track length of 8553.4 km—a scale that highlights the nation’s unparalleled urban infrastructure expansion. It is widely acknowledged that rail transit development serves as a barometer of urban construction and modernization. Given the extensive expansion of rail transit networks, ensuring operational safety has become a critical challenge. At the core of this challenge is structural safety, which is fundamental to maintaining system reliability. Among various structural forms, shield tunnels, constructed using the shield tunneling method and accounting for a significant proportion of modern urban transit networks, have increasingly emerged as a focus of safety-related research. These tunnels, now widespread across China, serve as a key component of underground space development.