The Analysis Of Ground Deformation And Segment Lining Mechanical Behavior During Shield Tunneling Construction

Shield tunneling has been widely used in the tunnel construction of the metro engineering.The accurate prediction of the ground deformation and lining force induced by shield tunneling is necessary to the tunnel design and construction.To analyse the ground deformation and segment lining mechanical behavior during shield tunneling construction,the main contents and results are presented as follows:Firstly,the mechanical response of the soft ground solved by different methods during tunneling has been compared.The ground movements which have been solved by step-by-step method and displacement controlled method in FLAC^3D are compared with the semi-analytical method.And the radius of the plastic zone,the stress and displacement of the soils around the tunnel boundary by the two numerical methods are investigated.The results indicate that,compared with the step-by-step method,the settlement by the analytical method is underestimated,the soil displacement and the plastic zone by displacement controlled method are overestimated.Besides,the soil around the bottom suffers from the tensile failure in displacement controlled method,which is unreasonable.Secondly,the influence of construction factors on the ground movement is studied using step-by-step method.The results show that,the grouting pressure has an important influence on the ground movement,thus it is efficient to reduce the settlement by increasing the grouting pressure.However,the influence of the face support pressure on decreasing the settlement is insignificant.Thirdly,a three-dimensional model,which includes the construction loads in the construction process of tunnel advance and adopts the shell-spring design model to simulate the segment lining,is established to analyse the segment lining mechanical behavior during shield tunneling construction based on FLAC^3D.In addition,the influence of the joint pattern on the stress and deformation of the liner is also investigated.The results show that,in the construction stage,the mechanical behavior of segment joints,ring joints and links between tunnel and joints are greatly different,the influence of thrust force on the lining is considerable.The continuous lining overestimates the rigidity of the lining.Compared with the straight rings,the efficacy of staggered rings is more excellent for the lining design.