On July 20, the last 3 meters of rock were precisely blasted, and Section 3 of the Jiaozhou Bay Second Tunnel, constructed by China Railway Tunnel Group under CREC, successfully penetrated the F13 undersea fault fracture zone—the longest of its kind under construction in China.
The Jiaozhou Bay Second Tunnel is a mega project connecting the east and west banks of Qingdao and is currently the world’s largest underwater road tunnel under construction. The tunnel spans 17.48 kilometers, with its deepest point 115 meters below sea level, and uses a combined drill-and-blast and shield tunneling method. Section 3, built by China Railway Tunnel Group, stretches 7,094.5 meters and utilizes the drill-and-blast method in the subsea segment.
The geological conditions of the project are extremely complex, requiring the tunnel to pass through the 560-meter-long F13 fracture zone, a petrochemical terminal area, and several other high-risk fractured sections, posing substantial construction challenges.
During construction, a complete technical standard for complex undersea fault construction was developed, providing valuable experience for similar projects.
