充填型浅层岩溶隧道溶洞处理技术研究

Study on Karst Cave Treatment Technology of Filling-Type Superficial Karst

浅层岩溶多发育于隧道拱部,并且由于溶洞充填介质的复杂多变,隧道往往会发生坍塌冒顶的现象。文章结合宣曲高速海德隧道对充填型浅层岩溶隧道进行失稳以及力学特征分析,通过直剪试验分析了含水率对充填红黏土物理力学性质的影响,结合有限元数值模拟对隧道坍塌冒顶进行分析,根据分析结果提出三台阶预留核心土法开挖配合"超前管棚+小导管注浆"超前支护的综合处理方案,结合现场给出了详细的施工技术措施。在处理段增设监测断面,通过位移、围岩压力角度来判断充填塌陷段的处理效果,数据表明,充填型溶洞的综合处理方案效果良好,对类似工程具有一定的借鉴作用。

Superficial karsts typically develop in the arch of tunnels. Due to the complexity and uncertainty of filling medium, tunnel collapse and roof fall frequently occur. This paper analyzed the instability and mechanical characteristics of the Haide tunnel, which is a superficial karst tunnel with filling medium. The effect of water content on the physical and mechanical properties of filled red clay was analyzed by direct shear test. The process of instability was analyzed by numerical simulation. Based on the above analysis, the excavation method called three-step and reserved core soil was put forward to treat the karst cave, paired with ＂Advanced Shedpipe Support ＋ Advanced Small Pipe Grouting＂. Then, the detailed construction technical measures were put forward based on the construction site. A monitoring cross section was added to the specific treatment section to judge the treatment effect to the roof fall section by displacement and surrounding rock pressure. The research results show that the comprehensive treatment plan of the filling karst cave is of good effect, and is referential for similar projects to some extent.