A simplified two-stage method was employed to provide an explicit solution for the time-dependent tunnel-rock interaction,considering the generalized Zhang-Zhu strength criterion.Additionally,a simplified mechanical m...A simplified two-stage method was employed to provide an explicit solution for the time-dependent tunnel-rock interaction,considering the generalized Zhang-Zhu strength criterion.Additionally,a simplified mechanical model of the yielding support structure was established.The tunnel excavation is simplified to a two-stage process:the first stage is affected by the longitudinal effect,while the second stage is affected by rheological behavior.Two cases are considered:one is that the rigid support is constructed during the first stage,and the other is that constructed at the second stage.Distinguished by the support timing at the seconde stage,different kinds of the“yield-resist combination”support method are divided into three categories:“yield before resist”support,“yield-resist”support,and“control-yield-resist”support.Results show that the support reaction of“control-yield-resist”is much higher than that of“yield before resist”if the initial geostress is not very high,but the effect is not obvious on controlling the surrounding rock deformation.So,the“yield before resist”support is much more economical and practical when the ground stress is not very high.However,under high geostress condition,through applying relatively high support reaction actively to surrounding rock at the first stage,the“control-yield-resist”support is superior in controlling the deformation rate of surrounding rock.Therefore,in the high geostress environment,it is recommended to construct prestressed yielding anchor immediately after excavation,and then construct rigid support after the surrounding rock deformation reaches the predetermined deformation.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42207176 and 52278402)Ningbo Public Welfare Research Program Project(Grant No.2023S100)+1 种基金Ningbo Natural Science Foundation(Grant No.2022J116)China's National Key R&D Program“Intergovernmental International Science and Technology Innovation Cooperation”(Grant No.2024YFE0105800).
文摘A simplified two-stage method was employed to provide an explicit solution for the time-dependent tunnel-rock interaction,considering the generalized Zhang-Zhu strength criterion.Additionally,a simplified mechanical model of the yielding support structure was established.The tunnel excavation is simplified to a two-stage process:the first stage is affected by the longitudinal effect,while the second stage is affected by rheological behavior.Two cases are considered:one is that the rigid support is constructed during the first stage,and the other is that constructed at the second stage.Distinguished by the support timing at the seconde stage,different kinds of the“yield-resist combination”support method are divided into three categories:“yield before resist”support,“yield-resist”support,and“control-yield-resist”support.Results show that the support reaction of“control-yield-resist”is much higher than that of“yield before resist”if the initial geostress is not very high,but the effect is not obvious on controlling the surrounding rock deformation.So,the“yield before resist”support is much more economical and practical when the ground stress is not very high.However,under high geostress condition,through applying relatively high support reaction actively to surrounding rock at the first stage,the“control-yield-resist”support is superior in controlling the deformation rate of surrounding rock.Therefore,in the high geostress environment,it is recommended to construct prestressed yielding anchor immediately after excavation,and then construct rigid support after the surrounding rock deformation reaches the predetermined deformation.
