A semi-empirical method for the design of support systems in underground openings

Abstract

A semi-empirical method has been developed for the design of support systems consisting of rock bolts/anchors, shortcrete/fibre-reinforced shortcrete, steel ribs and grouted arches to support tunnels and caverns, especially in poor rock conditions. The empirical relations for mobilizing factors of shortcrete and bolts/anchors have been deduced on the conservative side from extensive data of the Norwegian Geotechnical Institute (NGI) tables and charts for support systems presented by Barton et al. (1974). There is a reasonably acceptable correlation between the empirical approach and the proposed theory of estimating the support capacity, except for abnormal cases. The proposed method is simple to apply in the field. Special designs have been suggested for complex geological conditions for which the assumptions are not valid, such as in thick shear zones, etc. © 1995.