Qingdao Jiaozhou Bay Tunnel lies at the mouth of Jiaozhou Bay, connects Qingdao with Huangdao, and it crosses the sea area of Jiaozhou Bay. The overall length of the tunnel is 7800 meters, it divides into the land part and the underwater part, of which, the underwater part is 3950 meters long. This tunnel belongs to the city expressway. It began to construct on December 27, 2006 and fully went into operation on June 30, 2011, the reference period of design is about 100 years.
The geological condition of Qingdao Jiaozhou Bay Tunnel is volcanic rock, the covering layer is thin and the fault zone is intensive. It includes about 18 fault zones, and the largest span of the zone is 28.20 meters, the deepest one is 82.82 meters under the sea level. So the difficulty of construction is obvious.
The demand of the undersea tunnel is high and strict, so the protecting system is more important. The covering layer of concrete in this tunnel is 60mm. And the supporting anchor system is high-quality.
Self drilling anchor bolt is used to integrate the functions of drilling, grouting and anchoring, which can fill fractures effectively.
Anti-corrosion rock bolt has the good effect of preventing the rusting, especially the duplex coating rock bolt, it adopts two corrosion-prevention measurements on the bolt surface, hot-dip galvanizing and epoxy coating, which can separate water, oxygen, chloride and other corrosive medium. Meanwhile, it also create electric insulation layer which can insulate the electric current between steel bar and outside condition and then it reaches the good result of corrosion prevention.