关键词: 支护时机, 应变软化, 剪胀, 预留变形量, 隧道约束收敛理论

Abstract: If the surrounding rock with strain softening and shear dilation effect can be supported in reasonable time, it will be good for deepburied tunnel to keep stable and save cost. Based on convergenceconfinement method, a twostage analysis method of surrounding rocksupporting 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 threedimensional 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 postpeak shear dilation and strain softening behaviors is small. (2)For the rock mass with ideal elasticplastic 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.

Key words: supporting time, strainsoftening,  , shear dilation, reserved deformation, convergence-confinement method