Rheological Deformation Analysis Of Deep-buried Soft Rock Tunnel Considering Tunnel Face Effect And Support

For some areas with weak lithology,most tunnels are constructed in soft rock.Soft rock has rheological property,and the deformation will increase with time,which is not conducive to the long-term stability of the tunnel.Therefore,on the basis of considering the spatial effect of tunnel face and support effect,this thesis mainly studies the rheological deformation of surrounding rock in deep tunnel.The main contents and results of this thesis are presented as follows:（1）Based on Cvisc constitutive model,the numerical model of tunnel is established by using the numerical software FLAC^3D.During the numerical simulation,the influence of tunnel excavation time is taken into account and the longitudinal deformation curve considering the rheological property is obtained.On this basis,the numerical solution is verified by comparison with V-D curve and the influence of different excavation rate and rheological time on the longitudinal deformation curve is analyzed.The results show that when the excavation rate is higher and the rheological time is longer,the greater the deformation of surrounding rock will be.（2）Based on the theory of cavity expansion and the theory of elastic-viscoelastic correspondence,an analytical solution for rheological deformation of surrounding rock in deep buried tunnel considering volume deformation is derived.Compared with the existing theoretical solution and FLAC^3D numerical results,the accuracy of the analytical solution is verified.The influence of different rheological parameters,initial stress and rock mass parameters on surrounding rock deformation is discussed.The results show that the rheological parameters have great influence on the deformation rate and convergence time of surrounding rock,while the initial stress and rock mass parameters only have influence on the deformation rate and final deformation of surrounding rock.（3）The interaction between surrounding rock and support is analyzed by convergence confinement method.In the first stage,a method of solving fictitious support considering rheological property is proposed.In the second stage,the interaction between surrounding rock and support was analyzed,considering the spatial effect of tunnel face and rheological property.Based on this,an analytical solution for rheological deformation of surrounding rock in deep buried tunnel considering the spatial effect of excavation face and support effect is proposed.The influence of rock mass parameters and different supporting timing on surrounding rock deformation was studied.The results show that the longer the rheological time is,the smaller the virtual support is.The earlier the supporting timing is,the smaller the surrounding rock deformation will be in the stabilization stage.