3D Finite Elemnet Analysis On Shield Tunnel With Consideration Of Interaction Between Ground And Tunnel

With rapid development of shield tunnel at home and abroad and continuousinnovation of construction technology, excavation condition of shield tunnels isbecoming more and more complex and Deformation characteristics of tunnels underforce has a high research value. Making the problems of negative overburden, zerooverburden, shallow overburden and floating during the GPST sheild tunnelling as thesubject of my reserach, author gives the idea of3d finite element analysis on shieldtunnel with consideration of interaction between ground and tunnel. Research contentsmainly including aspects as follows:(1) Refined3-D infinite model including detail of tunnel segments, bolts betweensegments inside rings, bolts between rings and joints between segments is set up. Withthe calculation, rules of transverse deformation of model under force and reductioncoefficient of stiffness of sophisticated tunnels relative to3-D continuous tunnels areachieved. And with orthotropic constitutive model, relative deformation factors ofcontinuous tunnels under force after stiffness reduction can be achieved.(2) For different overburden depth, detailed deformation analysis of segment modelunder force is done with method of load-structure. Tunnel section deformation underforce and different overburden depth is achieved. Relationship among overburden depth,tunnel convergence, deformation situation and tunnel transverse reduction coefficient is analyzed. Parameter characteristics of several soil is also analyzed, which has referencevalue to follow-up study.(3) For situation in which overburden depth is always changing and includesnegative overburden, zero overburden and shallow overburden during shield tunnelexcavation, represented by method of shield tunnel without working well,3-D finitemodel is set up, in which the tunnel is reduced to a continuous one with stiffnessreduction. Process of shield excavated from ground to underground is simulated.Characteristics of deformation of shield under force along the length with the effect ofexcavation unload and mortar buoyancy. Effectiveness of two common anti-floatingmethods is studied.(4) Effects of several parameters of the3-D model with consideration of interactionbetween ground and tunnel is analyzed, mainly including impact of soil structure, soilparameter and water-soil coupling effect to tunnel deformation rule under force along thelength.Soil-tunnel,3-D finite element, equivalent stiffness reduction coefficient, overburdendepth, mortar buoyancy.