SUPPORT PRESSURE ASSESSMENT IN ARCHED UNDERGROUND OPENINGS THROUGH POOR ROCK MASSES

Himalayan tunnels provide challenging opportunities for working on the problem of assessment of support pressure in tunnels. A resume of the efforts by Indian researchers on this topic is presented in this pape r, with a brief review and comparison with the approaches of Bieniawsk i (1979) and Barton et al. (1974; Analysis of Rock Mass Quality and Su pport Practice in Tunnelling, and a Guide for Estimating Support Requi rements, Report by NGI, June). It is noted that Goel's classification of tunnelling conditions (Goel, 1994; Correlations for Predicting Supp ort Pressures and Closures in tunnels, Ph.D, Thesis, Nagpur University , India, p. 308) is complementary to the Q-system. Contrary to Terzagh i's theory, support pressures are observed to be independent of openin g size. (C) 1997 Elsevier Science B.V.