软弱围岩隧道管棚水平旋喷组合预加固变形规律

为研究软弱围岩地层管棚水平旋喷桩组合结构的预加固效果,采用三维弹塑性有限元方法对比分析了单独使用管棚、单独使用旋喷桩、管棚与旋喷桩组合预加固及无加固4种工况下隧道结构体系的位移变化规律。结果表明:1)水平旋喷桩和管棚2种工法中,水平旋喷桩预加固工法控制拱顶下沉、拱脚收敛值和掌子面稳定性能力显著;2)管棚预加固工法控制地表沉降的能力较强;3)管棚和旋喷桩组合结构控制拱顶沉降和拱脚收敛,掌子面水平位移性能突出,管棚水平旋喷桩组合结构使地表沉降减小91.3%,拱顶沉降减小76.2%,拱脚收敛减小76.3%,其地表最大沉降值为2.7 mm,拱顶最大沉降值为25 mm,拱脚最大收敛值为4mm,最小收敛值为-9.4 mm,加固效果明显。

Deformation Law of Composite Structure of Pipe Roof and Horizontal Jet-Grouting Pile Reinforcement in Tunneling in Weak Strata

The deformation law of tunnel structures in 4 cases, i.e., application of only pipe roof, application of only horizontal jet grouting piles, application of pipe roof coupled with horizontal jet grouting piles and application of no advance reinforcement, are studied by means of three dimensional elastic plastic finite element method, so as to investigate the effect of the pipe roof coupled with horizontal jet grouting piles on the deformation of tunnel in weak strata. Conclusions drawn are as follows: 1) The horizontal jet grouting pile method is superior in controlling crown settlement, arch spring convergence and face displacement, while the pipe roof method is superior in controlling the ground surface settlement。 2) The combination method of pipe roof and horizontal jet grouting piles results in outstanding control of crown settlement, arch spring convergence and tunnel face horizontal displacement: the ground surface settlement is reduced by 91.3%, the crown settlement is reduced by 76.2%, and the arch spring convergence is reduced by 76.3%; the maximum ground surface settlement is 2.7 mm, the maximum crown settlement is 25 mm, the maximum arch spring convergence is 4 mm and the minimum arch spring convergence is -9.4 mm.