Stability Analysis Of Tunnel Surrounding Rock Under Non-uniform Stress Field Under Seepage

With the great development of national infrastructure construction,various complicated geological conditions have been encountered in the underground engineering construction in recent years,among which the seepage field and non-uniform stress field have a very important influence on the stability of tunnel surrounding rock.Under the action of groundwater,due to the destruction of a certain range of rock mass around the tunnel,the permeability of rock mass around the tunnel will change,which will cause the change of the surrounding rock stress field.Under the coupling action of seepage field and non-uniform stress field,the influence on the deformation and failure of tunnel surrounding rock is more obvious.In this paper,the mechanical effects of seepage field and non-uniform stress field on tunnel surrounding rock are analyzed by theoretical analysis and numerical simulation,and the deformation characteristics of tunnel surrounding rock under non-uniform stress field are studied.Firstly,the coupling relationship between the seepage field and the non-uniform stress field is analyzed theoretically.Based on the Mohr-Coulomb criterion and the theory of elastoplastic mechanics,the analytical solution of the plastic zone of surrounding rock under the seepage is deduced.Secondly,according to the method of numerical simulation,combined with the engineering geological data of Galigong Mountain tunnel,the seepage mechanics model of tunnel is established,and the influence of different lateral pressure coefficient and pore water pressure on the failure of tunnel surrounding rock is analyzed-Finally,combined with the field support scheme,the tunnel support model was established by FLAC3D,the stability of surrounding rock before and after the tunnel support was analyzed,and the grouting reinforcement scheme was proposed to further study the waterproof and deformation control of surrounding rock in the tunnel.The following conclusions can be drawn from the above research:(1)By establishing the mechanical model of tunnel surrounding rock and lining under the action of seepage,the mechanical effect of tunnel seepage field on tunnel surrounding rock lining structure is analyzed,and the expression of external water pressure on the lining structure is deduced.The influence of different lining thickness and permeability of lining structure on external water pressure of lining structure is analyzed.(2)Based on theoretical analysis,the analytical expressions of stress and plastic zone of surrounding rock under non-uniform stress field under seepage are deduced.Combined with the engineering geological data of Galigong Mountain tunnel,the analytical expression and data were processed by Matlab software,and the effects of lateral pressure coefficient,pore water pressure and surrounding rock strength on the deformation and failure of the tunnel surrounding rock were analyzed.(3)Through FLAC3D numerical simulation combined with the engineering geological data of Gaoligong Mountain tunnel,the tunnel mechanics model was established.The effects of 12 working conditions on the seepage field,stress field,displacement field and plastic zone of the tunnel were studied when the lateral pressure coefficient was 0.5,1 and 1.5 and the pore water pressure was OMPa,2MPa,4MPa and 6MPa,respectively.(4)According to the support scheme of Gaoligongshan Tunnel,the stability of tunnel surrounding rock before and after the support is analyzed.In order to control the stability of tunnel surrounding rock more reasonably and prevent seepage and water plugging,the reinforcing support method of grouting reinforcement is put forward,and the influence of grouting thickness and permeability coefficient of grouting ring on the stability of tunnel surrounding rock is analyzed.Figure[71]Table[9]Reference[80]...