Abstract:

 The article expatiates on the causes for the overbreak/shortbreak in the drill+blast tunneling and analyzes on the impact of the overbreak/shortbreak on the increase of the tunnel construction cost. Finally, the article recommends three main approaches for the control of the overbreak/shortbreak during tunneling, i.e., ① strengthening the site construction management, which is the fundamental approach to reduce the overbreak/shortbreak; ② fulfilling NATM technology, which is the effective technical approach to reduce the overbreak/shortbreak; ③ replacing the traditional viewpoint of “overbreak rather than shortbreak” by the viewpoint of “less overbreak and less shortbreak”.

Key words: tunnel  , overbreak/shortbreak  , construction cost  , control approach