Abstract: The construction of tunnels on the Chengdu-Kunming 2nd railway encounters numerous geological challenges, including significant soft rock deformation, collapse, and water and mud gushing. To ensure construction safety and maintain project progress, a comprehensive tunnel water gushing treatment methodology, comprising exploration, interception, bypass, and drainage, is proposed for karst tunnels. In settings characterized by water-rich surrounding rocks and severe water and mud gushing, parallel heading tunnels are deployed to facilitate advance water discharge, water separation, and energy release and decompression. Additionally, a grouting technology termed "sealing and drainage" is utilized, applying grout from water-poor to water-rich sections. For tunnels surrounded by soft rocks with pronounced deformation, both long and short bolts are employed to reinforce the surrounding rock, thereby optimizing tunnel structure and enhancing its anti-deformation capacity. The implementation of these technologies has demonstrated effectiveness and offered distinct advantages in applicable tunnels.

Key words: Chengdu-Kunming railway tunnel, tunnel construction technology, water gushing treatment measures