In tunnels constructed according to the New Austrian Tunneling Method (NATM), the groundsurrounding the tunnel opening together with the shotcrete lining provide the main support of thetunnel. Hereby, the relatively large compliance of young shotcrete permits deformations, resulting inthe activation of the load-carrying capacity of the ground.In order to highlight the interaction between the creeping ground and the aging shotcrete shell indifferent geological conditions, material models for both granular and cohesive soil as well as forshotcrete are reported in this work [Spira, 2004]. Both material models for soil are characterized bynon-associative viscoplasticity including hardening/softening behavior. For the numerical simulationof shotcrete, a chemomechanical material model is employed [Ulm and Coussy, 1995].As an example problem, the effect of tunnel excavation and the subsequent application of theshotcrete shell on deformation and stress states in granular and cohesive soil is investigated. Basedon the obtained numerical results, the complex structural interaction between the creeping groundand the hydrating shotcrete shell characterized by the time-dependent increase in strength andstiffness is analyzed. Consideration of two types of soil and different viscous properties for the soilprovides insight into the deformation and loading of the shotcrete shell and, hence, the performanceof the aging shotcrete shell with respect to the different geological conditions.
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