Mechanical Analysis of Formwork Support in Underground Excavation Construction of Large Section Metro Stations in Karst Mountain Cities: a Case of Qianlingshan Park Station in Guiyang Metro Line 3

To address the formwork support stability challenges encountered during the underground excavation of large-section metro stations in karst geological conditions characterized by multiple karst caves and faults, this paper takes Qianlingshan Park Station of Guiyang Metro Line 3 as a case study. A novel support system integrating trolley-based concrete casting and disk-lock formwork scaffolding is proposed. The construction scheme of this system is detailed, and its mechanical characteristics, including stress distribution in both the trolley formwork and scaffolding structure, are analyzed alongside safety assurance measures. The successful implementation of this project demonstrates that the proposed technical system effectively mitigates disaster risks in large-span underground engineering within karst geology. It achieves safe, high-quality, and efficient construction outcomes, providing a valuable reference for similar engineering projects in comparable geological environments.