地下水对深埋软弱围岩隧道初期支护结构破坏及其控制措施研究

Research on Damage of Groundwater to the Initial Support Structure of Deep Buried Soft Surrounding Rock Tunnel and Its Control Measures

针对隧道施工期间砂质板岩、炭质千枚岩及绿泥石片岩等软弱围岩在地下水作用下发生软化、剥落、坍塌,继而引发支护变形侵限、喷射混凝土软化剥落、钢架扭曲失稳等灾害,以木寨岭公路隧道2号为依托工程,通过现场试验、监控量测等手段,分析地下水对深埋软弱围岩隧道初期支护结构失稳及破坏的影响,并提出了在地下水富集区,采用高强预应力锚索支护体系代替传统约束锚杆、环向注浆锚杆以及超前小导管注浆加固围岩的支护方法,降低了混凝土注浆压力及施工难度,避免因锚杆注浆不到位形成渗流通道而影响开挖围岩及初期支护强度,并通过采用高强预应力锚索加固措施,从而提高围岩自承能力及初期支护稳定性。

The softening, peeling and collapse of soft surrounding rocks such as carbonaceous slate and chlorite schist under the action of groundwater during tunnel construction will cause disasters such as support deformation invasion, shotcrete softening and peeling, steel frame distortion and instability, etc. In this paper, based on the Muzhailing Highway Tunnel, by means of field test, monitoring and measurement, the influence of groundwater on the instability and failure of initial support structure of deep buried soft surrounding rock tunnel is analyzed. In the groundwater enrichment area, a high-strength prestressed anchor cable support system is proposed to replace the traditional support method of strengthening the surrounding rock with restrained anchor bolt, circumferential grouting anchor bolt and advance small conduit grouting, which reduces concrete grouting pressure and construction difficulty, minimize the influence of surrounding rock excavation and initial support strength, and through the adoption of high-strength prestressed anchor cable reinforcement measures, the self-supporting capacity of the surrounding rock and the stability of the initial support are improved.