Application of Submodeling Technique in Numerical Modeling of Mechanized Tunnel Excavation

This research proposes a novel methodology of applying submodeling technique in the numerical simulation of mechanized tunnel excavation. A submodel is a smaller scale cut out of the full scale model (global model) in which the more in detail simulations along with higher degree of precision are conducted. Apparently, the submodel should include the near field around the TBM that is significantly affected by tunneling process and the region of interest such as ground surface where the model responses have to be surveyed. The appropriate size of the submodel is found by evaluation of the strain energy distribution in the domain while the energy gradient has to fulfill the predefined criterion. To analyze the submodel, the nodal displacements are derived from the global model and applied to the boundaries of the submodel. Using the proposed submodeling technique in the tunneling, the computational costs are reduced, while the submodel provides realistic prediction of the deformations in the system and lining forces. Finally, the proposed submodeling method is applied in both 2D and 3D tunneling simulations while two types of submodeling strategy (fixed submodel and moving submodel) are adopted for the 3D simulations. The results indicate that both approaches are adequate for predicting the lining forces and ground movements.