Naoki MATSUOKA

Examination on construction loads acting on shield at sharp curve by using measured data.

Supervisor  Mitsutaka SUGIMOTO

Today, shield is controlled by expert system. Since there are many unknown properties such as ground properties, external forces and construction loads, this system is based on empirical rules and does not have a theoretical background. To overcome there problems, the kinematical shield model considering the ground-shield interaction is required. Since nowadays, underground structures in cities are very congested, shield tunnel has been constructed in deep underground with sharp curve, Furthermore, the stress in segment due to construction loads is larger than before, since segment has been wider and thinner for saving the cost.
Therefore, this study aims to examine the validity of the construction loads obtained by the shield kinematic model. That is, the simulation on the shield behavior at a sharp curve, where segment damage due to construction loads appears intensively, was carried out. And the 3D-FEM analysis on segment behavior by using the obtained construction loads was done. Finally the construction loads obtained by the shield kinematic model was validated, comparing the analyzed segment displacements with the measured one. As a result, the following conclusions were obtained.
1) We modified the model to input coefficient of sub ground reaction at passive and active state separately.
2) The simulated shield behavior at the sharp curved section by the shield kinematic model has a good agreement with the observed one.
3) The simulated displacement of the segment by the 3D-FEM analysis has a good agreement with the observed one.
4) The construction loads by the shield model was validated.