The Tunnel Boring Machine Advancements in Horizontal and Up-Hill Tunnels

Abstract

Problem statement: Nowadays high levels of experience have been acquired in the excavation of horizontal tunnels using TBM, especially as far as tunnels with small diameters (about 4 m wide) are concerned. Less experience has been acquired in the excavation of tunnels under difficult alignment conditions, as in the case of steeply inclined excavations (up-hill tunnels). Approach: This study presented the results of studies which compare the production data collected for tunnels excavated with TBM in "normal" conditions (horizontal tunnel), with those derived from steeply inclined excavations (up-hill tunnels). Results: From an examination of the results obtained in the studied cases a net difference appears evident in terms of productivity between horizontal and up-hill excavations. Conclusion: Such net difference between horizontal and up-hill excavation productions can be attributed to the greater burdens of times necessary for the supply of materials and personnel, the regripping operations with fall preventer systems and, in general, the greater difficulties of carrying out ordinary and extraordinary maintenance of the machines in particularly difficult altrimetric conditions.