Name:Hiroaki ABE Numerical Analysis on the Lining Behavior of SENS Supervisor: Mitsutaka SUGIMOTO SENS has been adopted for the first time in the world during the construction of Sanbongihara tunnel on the Tohoku Shinkasen. In the above project, cracking occurred in the longitudinal lining of the tunnel, and furthermore underground water leaked through the cracks was observed. It is considered that the cracking is due to the floating of the inner mold in the fresh concrete of the primary lining as it is far away from the shield machine. However, behavior of the lining of SENS has not been represented by analysis, cracking mechanism is not clear. As the analysis technique, in general, there are a three-dimensional finite element analysis and a two-dimensional framed structure analysis. The former can not consider the three-dimensional effect of the tunnel, and the latter can not represent the behavior of the lining that is lifted by buoyancy due to water pressure and concrete pressure. Therefore in this study, we have developed a three-dimensional analysis model that takes into account the loading conditions, construction process, and factors to affect the behavior of the inner mold and lining in SENS. In this study, we implemented a parametric analysis on some values that define the ground reaction curve. Those values are initial displacement, the coefficient of horizontal earth pressure and the coefficient of ground reaction. In order to verify the validity of the analytical model, the effect of the three parameters examined on the analysis result. The measured bending moment and axial force were comparing with the calculatingly them of bending moment and axial force, and we estimate at the parameters to have a good fitting. As a result, we found the followings. (1) Initial displacement of the ground =10mm, the ground stress and concrete pressure have a roughly balanced. (2) The effective earth pressure acting on the inner frame and the primary lining is close to equal pressure distribution. (3) Estimating the coefficient of ground reaction substantially coincides with the value calculated from the modulus of elasticity by field survey.