Name:Syougo INADA
Development of FE Model Including Interaction Between Shield and Segment
Supervisor: Mitsutaka SUGIMOTO
Recently, shield tunnels have been constructed in deeper underground with sharp curve, as underground space in urban area became congested. Furthermore, segments become thinner and wider for saving its cost. Consequently, the stress in segment during construction tends to increase and then the segment damage during construction was increased. But these mechanisms have not yet been made clear quantitatively. In addition, to study segment behavior, the simplified FE model was developed, which can evaluate the segment deformation in the transverse direction of the segment due to tail force, and the segment rigid displacement in the transverse direction of the tunnel due to jack thrust, separately. However, when the obtained results are in a nonlinear region, precise displacements can not be expected because a nonlinear spring is used in the analysis.
Therefore, in this study, the unified FE model, which can consider the influence of the tail force and jack thrust on segments by modeling shield and segment at once, was developed. To make clear the construction loads acting on segments, the followings were carried out:
1) The construction loads are estimated through the simulation of the shield behavior using the kinematic shield model;
2) The 3DFEM analysis on shield tunnel displacement is carried out using the calculated construction loads, and the obtained segment displacements are compared with the field measured data; and
3) The influence of the construction loads on the segment behavior in sharp curve is examined.
As a result, the followings were concluded:
1) The unified FE model, which uses non-tension spring with bilinear type as the tail seal spring, can represent touching between shield tail and segment;
2) The proposed model can represent the segment deformation in vertical direction and the rigid displacement of the segment to the convex side of the tunnel; and
3) The calculated deformation of the segment was smaller than the measured one at the measurement section. This is because the model is a static model at the excavation of the last segmental ring. This fact indicates that a phase analysis during excavation is necessary to represent the measured data.
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