TIME-DEPENDENT TUNNEL CONVERGENCE .1. FORMULATION OF THE MODEL

Abstract

The understanding of the mechanism of tunnel convergence is essential for designing the required support of a tunnel. To take various time effects on the convergence-confinement relation into account, it is possible to correlate different factors with time, then to deal with their collective effects. As a result, the time-dependent tunnel deformation problem can be modelled as a viscoelastic problem. The solutions of various visocoelastic models can be obtained from the corresponding elastic solution based on a standard procedure. In this paper, a hierarchical approach, which considers: (1) the rheological properties of a rock mass; (2) the advancement of the tunnel; and (3) the tunnel-support interaction is proposed to model the excavation/construction process during the tunnelling in a rock mass with rheological properties. The time-dependent factors considered in the proposed model are discussed. Subsequently, the theoretical formulation of this model is developed.