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Ch. Hellmich, H.A. Mang:
"Influence of the Dilatation of Soil and Shotcrete on the Load Bearing Behavior of NATM-Tunnels";
Felsbau, 17 (1999), 1; 35 - 43.

This paper deals with the application of thermochemoplastic and viscoplastic material laws to 2D (plane strain) numerical simulations of the excavation of tunnels driven according the New Austrian Tunnelling Method (NATM). The main goal of this work is to show the influence of material characteristics (above all the dilatation behavior of soil and shotcrete) on the overall structural behavior. As for the tunnel shell, thermal and chemical dilatation of shotcrete may lead to a redistribution of bending moments, and, via tensile forces in the longitudinal direction, to cracking of the tunnel shell, as it is known from in-situ observations. The soil dilatation (overconsolidated versus normally compressed soil) has a strong influence, both qualitatively and quantitatively, on the forces acting on the tunnel shell. As for the tunnel shell, thermal and chemical dilatation of shotcrete may lead to a redistribution of bending moments, and, via tensile forces in the longitudinal direction, to cracking of the tunnel shell, as it is known from 'in-situ' observations. The soil dilatation (overconsolidated versus normally compressed soil) has a strong influence, both qualitatively, on the forces acting on the shell.

Keywords: viscoplasticity, thermochemoplasticity, dilatation, normaly compressed soil, overconsolidated soil