Naoya Koshiba

Post-mortem analysis of Ground behavior around SENS by three-dimensional continuum FEM model

Mitsutaka Sugimoto

　In the construction of an in-situ concrete support system with TBM (hereinafter referred to as SENS), a primary concrete lining is pressurized and filled between the ground and the inner frame to form a tunnel lining continuously. Therefore, the inner frame receives buoyancy continuously due to fresh concrete and the primary lining tends to move upward rigidly. As the time passing, the primary lining is hardened and the earth pressure from the ground acts on it to estimate this acting earth pressure, it is necessary to estimate the behavior of the inner frame, which changes three-dimensionally and sequentially. Then an analytical model, which can express the interaction of corresponding ground, primary lining, and inner form is required.
　In the past research, a three-dimensional analytical model (beam-spring model), which takes into consideration the load condition and the construction process of SENS was developed and it was verified using in-site measured data of actual tunnels. Furthermore, the influence of excavation on the ground movement around the tunnel was investigated, using the site measured data at a shallow tunnel, where ground movement is expected to occur, by a beam spring lining model and a three ? dimensional ground continuum model. Comparing the calented ground movement with the measure one, the validity of the ground displacement behavior was confirmed.
　This research, aims to investigate the influence of construction conditions on the ground movement around the tunnel, using the three-dimensional continuum model with the beam spring lining model. The targeted tunnel is Youtei tunnel. As a result, the effects of the construction conditions on the ground surface displacement were confirmed, and the basic information for construction management was obtained.