Abstract:The tunnel group along the Yuewei Port Connecting Highway is situated in a typical karst landform area with intense karst development, characterized by highly concealed and morphologically complex caves. To address such complex geological conditions, the project adopted a technical framework of "advanced detection-risk classification-dynamic treatment" and implemented a collaborative mechanism among survey, design, and construction teams. This approach enabled proactive karst hazard mitigation and efficient project advancement. Taking Tunnel No.2 as an example, the left tunnel's large karst cave at the invert was crossed using a pile-raft structure, with dynamic optimization of pile foundation depth and raft thickness based on construction-stage surveys. For the right tunnel, advanced drilling revealed adjacent cavities, leading to comprehensive treatment measures including cavity protection, reinforced arch walls, and a multi-level drainage system, effectively mitigating collapse risks. Practical results demonstrate that this technical framework reduced the construction period, successfully shifted karst tunnel engineering from passive emergency response to proactive risk management. It provides reusable technical and managerial insights for karst tunnel construction in southwestern China.
