ABSTRACT
In this paper, we propose a simplified chamber pressure model for Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) tunneling in granular soils, both during excavation and standstill. Three physical processes, (1) muck compression/decompression; (2) chamber fluid seepage; and (3) rotation induced unlevel muck surface, are identified and modeled. The model satisfies the muck mass conservation constraint, but relaxes its motion equation by assuming quasi-static condition and gas substance even distribution. The model is designed as a state machine, with total chamber gas volume, liquid volume and gas substance amount chosen as the state variable to characterize the chamber pressure distribution. TBM operations are used to update the state variable and track the chamber phase evolution over time. The model is implemented with data from the N125 tunneling project in Seattle for model demonstration and evaluation.
