Recently, the Huama Tunnel on the Lanzhou-Chongqing Railway, a national key project, was successfully holed through, marking a new breakthrough by China Railway Construction Corporation in its technical capability for constructing long and large tunnels under complex geological conditions.
1. The 12,580-meter extra-long, extremely high-risk double-track tunnel: Huama Tunnel
The Huama Tunnel has a total length of 12,580 meters. It is one of the nine extra-long, extremely high-risk double-track tunnels over 10 kilometers on the Lanzhou-Chongqing Railway. It is the third extra-long, extremely high-risk double-track tunnel over 10 kilometers to be successfully holed through after the Tianchiping Tunnel, the first to be holed through, and it is the tunnel on the Lanzhou-Chongqing Railway with the most complex geological conditions and the greatest variety of geological hazards. The tunnel passes through 7 fault zones, 2 synclines, and 2 anticlines. Since construction began in March 2014, the construction unit has successively overcome geological hazards such as high ground stress, large deformation of soft rock, water and mud inrush, high gas, and high ground temperature, achieving the successful holing-through of the tunnel.
2. The 7,583-meter secondary high-risk long and large tunnel: Liujiazhuang Tunnel
The Liujiazhuang Tunnel on the Shanghai-Kunming Railway has a total length of 7,583 meters. Located where it crosses the Wumeng Mountains, it has extremely complex geological conditions. It is a typical secondary high-risk long and large tunnel and also a key and difficult control tunnel on the Shanghai-Kunming Railway, with a high safety control coefficient and particularly great construction difficulty. Through scientific organization and meticulous construction, the project overcame difficulties such as mud and water inrush, high gas, and poor surrounding rock stability. In March 2014, it achieved the safe holing-through of the high-gas work area from the exit of the Liujiazhuang Tunnel to the inclined shaft on the Guizhou section of the Shanghai-Kunming Passenger Dedicated Line, marking a major breakthrough in the project's tunnel construction.
3. The 12,030-meter single-tube double-track tunnel: Zeya Tunnel
The Zeya Tunnel on the Jinhua-Wenzhou Railway has a total length of 12,030 meters. It is a single-tube double-track tunnel, the longest tunnel on the Jinhua-Wenzhou Railway and one of the key control projects. It is known as the "No. 1 Longest Tunnel in East China." The horizontal distance between the tunnel and the Zeya Reservoir is 520 meters at the closest point, and the water inflow during construction was extremely large. The project organized several expert demonstration meetings, and on-site unit leaders investigated the geological conditions, fault strike, and sources of water inflow to formulate a feasible construction plan, laying a good foundation for the construction of long and large tunnels in water-bearing conditions. In April 2013, the monthly excavation of the entrance section of the Zeya Tunnel on the Jinhua-Wenzhou Railway exceeded 249 meters, setting a new excavation record for tunnels on the Jinhua-Wenzhou Railway. It also accumulated rich experience for the construction party in smooth blasting technology.