Effect of orientation of fracture zone on tunnel behavior - Numerical Investigation

Abstract

ABSTRACT: This paper concerns the effect of orientation and geometric characteristics of a fracture zone on the tunnel behavior using a numerical investigation. A parametric study was executed on a number of drill and blast tunnelling cases representing different fracture and tunnelling conditions using two and three dimensional finite element analyses. The variables considered include the strike and dip angle of fracture zone relative to the longitudinal tunnel axis, the width and the clearance of the fracture zone, the tunnel depth, and the initial lateral stress coefficient. The results of the analyses w ere examined in terms of the tunnel deformation including crown settlement, convergence, and invert heave as well as shotcrete lining stresses. The results indicate that the tunnel deformation as well as the shotcrete lining stress are strongly influence d by the orientation of the fracture zone, and that such a trend becomes more pronounced for tunnels with greater depths.Keywords: Drill and blast tunnel, Finite element analysis, Deep tunnel, Fracture zone