公路隧道穿越特大型溶洞施工处治技术——以太平隧道为例

Construction and Treatment Technologies of Highway Tunnel Crossing Super-large Caves:A Case Study of Taiping Tunnel Project

隧道开挖过程中若揭露特大型溶洞,如何安全、快速、经济地穿越特大型溶洞是公路隧道建设的重大需求。传统的桩基组合结构不适用于溶洞底板条件差的情况。依托湖北宣鹤高速太平隧道工程,针对特大型溶洞隧道的工程和水文地质状况等展开分析,提出多种穿越溶洞的技术方案,通过多维度比选,确定双拱明洞+回填暗挖方案。现场监测及风险评估结果表明:隧道沉降经历2个变形阶段,快速沉降期的变形占总变形的82.6%以上,收敛沉降期变形不超过总变形20%。项目采取的溶洞穿越方案能显著提高隧道施工的效率、安全性和经济性,同时有效地预防了潜在的重大风险。

When the super-large karst cave is exposed during the tunnel excavation,how to cross the super-large karst cave safely,quickly and economically is a significant demand in the construction of highway tunnels.The traditional pile foundation composite structure is not suitable for the condition of the poor cave floor.Based on the Taiping tunnel project of Xuanhe expressway in Hubei Province,this paper analyzes the engineering geology and hydrogeology conditions of the super-large tunnel,puts forward a variety of technical schemes for tunnel crossing the Karst caves,and determines the scheme of double-arch open-cut tunnel combing with backfilling and mined excavation through multi-dimensional comparison.The results of field monitoring and risk assessment show that the tunnel settlement would experience two deformation stages,the deformation in the rapid settlement period can accounts for over 82.6%of the total deformation,and the deformation in the convergent settlement period accounts for less than 20%of the total deformation.The Karst cave-crossing scheme of the project can significantly improve tunnel construction efficiency,safety,and economy and effectively prevent potential risks.