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Ch. Hellmich, M. Lechner, R. Lackner, J. Macht, H.A. Mang:
"Creep in Shotcrete Tunnel Shells";
in: "Creep in Structures", S. Murakami, N. Ohno (ed.); issued by: International Union for Theoretical and Applied Mechanics; Kluwer Academic Publishers, Dordrecht, 2001, 217 - 229.

Creep of shotcrete is modelled within the framework of thermodynamics of chemically reactive porous media. The process of creep is divided into a short-term and a long-term part. Short-term creep stems from stress-induced water movement within the capillary pores of shotcrete, located between the already formed hydrates which are the reaction products between cement and water. Thus, short-term creep is related to the accumulation of initially (micro)stress-free hydrates. Hence, it depends on increments of (macro)stress. Long-term creep results from dislocation-like processes within the (micro)stressed hydrates. Therefore, this process depends on the total (macro)stress. Microcracking of shotcrete is modelled by means of multisurface chemoplasticity. Moreover, the model accounts for chemical shrinkage and hydration heat. Finally, the significance of creep of shotcrete for real-life structures is shown by means of 3D hybrid analyses of a railway tunnel. The term `hybrid' reflects the combination of advanced material modelling with in-situ displacement measurements in the framework of nonlinear Finite Element analyses.

Keywords: tunnel, shotcrete, creep, hybrid method, Rankine criterion, incremental constitutive equatio, short-term creep