泥石流堆积体隧道稳定性控制技术研究

Research on Stability Control Technology of Tunnel in Debris Flow Accumulation Body

泥石流堆积体隧道围岩松散破碎,黏聚力差,掌子面及洞周极易坍塌,初支拱脚沉降变量大,初支结构整体失稳风险高,施工安全难以保证。为此,结合红桥关隧道穿越泥石流堆积体段工程,开展泥石流堆积体隧道稳定性控制技术研究。实践表明:采用管棚与玻璃纤维锚杆相结合的掌子面超前支护措施,可增强掌子面稳定性,掌子面向隧道净空变形破坏得到控制;采用“先固后钉法”的围岩加固技术(即地表竖向、洞内纵向群桩注浆加固和土钉加固围岩),改善了围岩物理力学特性及抗变形破坏能力;采用锚桩与横担梁相联合的初支拱架沉降控制技术,解决了隧道初支拱架锁脚部位沉降问题,使拱架结构稳定性大幅提高,保证了隧道安全高效施工。

The tunnel passes through debris flow accumulation body,with loose and fragmented surrounding rock,poor cohesion,and easy collapse of the tunnel face and surrounding area.The settlement variable of the initial support arch foot is large,and the overall instability risk of the initial support structure is high,making it difficult to ensure construction safety.For this purpose,combined with the Hongqiaoguan Tunnel crossing the debris flow accumulation section project,research on stability control technology for debris flow accumulation tunnel is carried out.Practice has shown that the use of advanced support measures for the tunnel face combined with pipe shed and glass fiber anchor rods has enhanced the stability of the tunnel face and controlled the deformation and damage of the tunnel face towards the tunnel clearance;the surrounding rock reinforcement technology of′first consolidation and then nailing method′(i.e.surface vertical and tunnel longitudinal group pile grouting reinforcement and soil nail reinforcement of surrounding rock)has improved the physical and mechanical properties and deformation and failure resistance of the surrounding rock;the settlement control technology of the initial support arch combined with anchor piles and cross arm beams has solved the settlement problem of the locking foot of the initial support arch in the tunnel,improved the stability of the arch structure,and ensured the safe and efficient construction of the tunnel.