Abstract:

A forked section is arranged in Jiaozhou Bay tunnel. Due to the shallow cover, poor geological conditions and complex ground surface environment of the forkedsection of the tunnel, there are great difficulties in the design and construction of the forkedsection. The range of the smallspaced tunnel section is determined by means of engineering analogy and numerical simulation. Concrete filling and tie bolts are adopted to reinforce the rock pillar of the smallspaced tunnel section. Pregrouting, primary support strengthening and bench excavating method are adopted for the large crosssection tunnel section. Microvibration blasting technology is adopted during the construction. In the end, rapid construction is achieved for the forkedsection. The monitoring results show that the support parameters, construction technologies and construction program adopted are rational and reliable.

Key words: Jiaozhou Bay tunnel, forked tunnel, smallspaced tunnel, large crosssection tunnel, rock pillar reinforcement, microvibration blasting, monitoring