Rational Design of Tunnel Supports: An Interactive Graphics Based Analysis of the Support Requirements of Excavations in Jointed Rock Masses: Fid-Bau Portal

Rational Design of Tunnel Supports: An Interactive Graphics Based Analysis of the Support Requirements of Excavations in Jointed Rock Masses

M. D. Voegele

Abstract

The Distinct Element methods portray a rock mass as a two-dimensional assembly of discrete blocks. There are no restrictions of block shapes or magnitudes of displacements and rotations. In the configurations used in this report, the Distinct Element method is coupled to a graphics terminal so that movements of the blocks are visually available as the computer calculates them. In Chapter II, a brief survey of the methods commonly used to analyze the behavior of jointed media is presented. Common to these methods surveyed is the realization that the observed behavior of a jointed mass is different from the behavior of a continuum. Chapter III is devoted to providing numerical verification of the Distinct Element method. In particular, several comparisons to limit equilibrium solutions are presented. The comparisons are favorable. The other chapters are concerned with the behavior of a jointed rock mass when disturbed by an excavation. The discussion covers two broad topics: (a) excavations that are stable without external support, and (b) excavations that require external support. The behavior of the jointed mass is typically illustrated by means of contact force distributions within the mass and through the development of arching. For those excabations requiring support, computer-generated ground reaction curves are presented. (Author)