为确保隧道稳定、节约成本，针对围岩应变软化与剪胀效应下深埋隧道的合理支护时机，基于隧道约束收敛理论，提出围岩-支护作用2阶段分析思路，引入初期支护屈服轴力与围岩变形折减率作为合理支护时机的判据。采用三维有限差分软件求解初期支护屈服轴力与围岩变形折减率，分析不同围岩质量、支护类型、初始应力、临界塑性软化系数、剪胀角下围岩预留变形量范围，确定深埋隧道合理支护时机。结果表明： 1）岩体质量与初始应力对隧道合理支护时机影响较为显著，但岩体峰后剪胀与应变软化特性较小； 2）对于理想弹塑性或剪胀性不明显的岩体，采用内部支护对维持岩体稳定性非常有利，既可减小岩体的应力释放，又可增大围岩变形控制效果。
If the surrounding rock with strain softening and
shear dilation effect can be supported in reasonable time, it will be good for
deepburied tunnel to keep stable and save cost. Based on convergenceconfinement method, a twostage analysis
method of surrounding rocksupporting interaction is
proposed, and yield axial force of primary support and reduction rate of
surrounding rock deformation are introduced to determine reasonable support
time. Then, based on threedimensional finite
difference software, yield axial force of primary support and reduction rate of
surrounding rock deformation are explored, and the reserved deformation range
under the influence of different surrounding rock quality, support type,
initial stress, critical plastic softening coefficient, and shear dilation
angle is analyzed. The results indicate that: (1) The rock mass quality and
initial stress have significant impact on the support time of the tunnel, but
that of the postpeak shear dilation and strain
softening behaviors is small. (2)For the rock mass with ideal elasticplastic or unobvious shear dilation,
internal support is beneficial to maintaining rock mass stable, which cannot
only reduce the stress release of rock mass, but also improve the deformation
control effect of surrounding rock.
