富水粉细砂隧道失稳破坏特征分析及增稳固结技术研究

Analysis of Tunnel Instability and Damage Characteristics in Waterrich Silty Fine Sand Formations and Research on Stabilization and Consolidation Techniques

桃树坪隧道穿越富水粉细砂地层,施工过程中极易出现大变形、涌水涌砂和坍塌等一系列破坏特征。通过对隧道失稳破坏的分析,总结了隧道在富水粉细砂条件下失稳破坏的特征,分析了破坏特征发生的机制,认为隧道的破坏主要由围岩岩性和地下水造成;由隧道破坏机理提出了增稳固结措施,通过超前降水、超前小导管注高分子化学浆对掌子面前方砂层进行预先固结,提高钢架整体刚度,通过对扰动砂层进行灌浆和回填等措施进行固结,围岩的自承能力得到提高。从处理后围岩的情况、涌水量和监测情况分析发现,增稳固结技术能从根本上提高围岩的自承能力,抑制发生失稳破坏,为隧道在富水粉细砂地层中的施工提供借鉴。

Taoshuping Tunnel passes through water-rich silty fine sand formations,where a series of destructive phenomena such as significant deformation,water and sand gushing,and collapse are prone to occur during construction.By analyzing the unstable failures of the tunnel,the characteristics of instability and failure under the conditions of waterrich silty fine sand were summarized.The mechanisms of these failure characteristics were analyzed,and it is believed that the tunnel’s failure is mainly caused by the lithology of the surrounding rock and groundwater.Based on the tunnel failure mechanism,stabilization and consolidation measures are proposed.These measures include advanced dewatering and advanced small-diameter pipe grouting with high molecular chemical slurry to pre-consolidate the sand layer ahead of the heading,improving the overall stiffness of the steel frame.Grouting and backfilling measures are implemented to consolidate the disturbed sand layers,thereby enhancing the self-supporting capacity of the surrounding rock.Through analysis of the post-treatment condition of the surrounding rock,water inflow volume,and monitoring data,it is found that the stabilization and consolidation techniques can fundamentally improve the self-supporting capacity of the surrounding rock,suppress instability and failure,providing valuable references for tunnel construction in water-rich silty fine sand formations.