| Popis: |
Problem statement: Nowadays high levels of experience have been acquired in the excavation of horizontal tunnels using TBM, especia lly as far as tunnels with small diameters (about 4 m wide) are concerned. Less experience has been acq uired in the excavation of tunnels under difficult alignment conditions, as in the case of steeply inc lined excavations (up-hill tunnels). Approach: This study presented the results of studies which compar e 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 neces sary for the supply of materials and personnel, the regripping operations with fall preventer systems a nd, in general, the greater difficulties of carryin g out ordinary and extraordinary maintenance of the machines in particularly difficult altrimetric condition s. |
