COMPUTER AIDED DESIGN OF SUPPORT SYSTEM FOR UNDERGROUND OPENINGS

Abstract

Rockmass in the underground contains so many pl'anes of weakness. Hence, At can be considered as a collection of separate• blocks tightly fitted in a 3D mosaic, The overall behaviour of rock, surrounding an underground excavation depends mainly on the system of cross joints and bedding planes. If an opening is created in such a rockmass, the instability is mainly due to the movement of these rigid blocks into the excavated face. A computer program UWEDGE in Fortran 77 (with GrafX library of subroutines) has been developed to identify the potentially sliding blocks. The analysis is based on the tetrahedral wedge analysis for underground openings. Instability of wedges due to lifting, sliding on a single face and sliding on two faces are considered. Rotational instability is neglected in this analysis. Optimal and timely reinforcement in the form of rock bolts, shotcrete and weld mesh has been intr'oduced to check the instability. A graphics package is developed so as to gain insight into the mechanics of failure around an underground opening. Elevation, side view and 3D view of the potentially sliding wedges are shown, to have a fair idea on the size of the wedge. The extent of bolting rods into the rockmass can be visualised in elevation and side view. Thus the graphics part of they program as a whole, enables user to have a physical feeling of the problem.