Abstract:

The authors focus on tunnel construction in three extreme environments: difficult mountainous areas, deep water areas, and sensitive urban areas. In particular, they meticulously organize and outline the primary challenges, relevant technological advancements, and future developmental trends associated with tunnel construction in these environments. Regarding extreme conditions such as high stresses, high temperatures, high altitudes, and active fault zones in difficult mountainous areas, the authors discuss the deformation mechanism, failure modes, and protective strategies of surrounding rocks and tunnels. It suggests that in the future, more accurate prediction models can be established using big data, machine learning, and other methodologies to enable realtime monitoring and risk assessment of tunnel construction processes. Further, regarding extreme conditions such as high water pressures, intense earthquakes, and high erosion rates in deep water areas, the authors delineate the deterioration and failure mechanisms of tunnel segments and joints employing the immersed tube and shield tunneling methods under multifactor coupling. Additionally, the authors summarize key technical strategies to improve the mechanical robustness and durability of these structures while advocating further research on the waterproofing, seismic, and erosion resistance of submarine tunnel segment joints, thus establishing a comprehensive theoretical and technical system. Finally, regarding the complexities of tunneling through existing tunnels, sensitive structures, and underground obstacles in sensitive urban areas, the authors summarize environmental response laws, relevant geological deformation assessment methods, and technical control strategies associated with shield tunneling and pipe jacking methods. They propose that in the future, machine learning and alternative technologies can assist in tunnel construction, improve prediction accuracy and control, and minimize disturbances to the urban environment throughout the construction process. Overall, although pertinent research results offer crucial support for tunnel construction in extreme environments, certain technologies need further improvement and standardization in their practical applications to guide subsequent engineering construction. With the development of nextgeneration information technology, future tunnel construction will inevitably move toward digitization, intelligence, and automation, ensuring the safety, sustainability, and efficiency of tunnel construction in extreme environments.

Key words: tunnel, extreme environments, hazardous mountainous areas, deepsea waters, sensitive urban areas, construction technique