After six years of construction, the West Qinling Tunnel on the Lanzhou-Chongqing Railway——China's longest railway tunnel currently under construction——achieved full breakthrough on the 19th. As a controlling project of the Lanzhou-Chongqing Railway, the breakthrough of the West Qinling Tunnel has laid a solid foundation for the opening of the railway to traffic.

Liu Jinliang, project manager of the West Qinling Tunnel Project Department of the Third Company of China Railway 18th Bureau Group, introduced that the West Qinling extra-long tunnel has a total length of 28.2 kilometers and is a controlling project of the entire Lanzhou-Chongqing Railway. The tunnel was constructed using a combination of TBM (full-face hard rock tunnel boring machine) and drill-and-blast methods, making it the railway tunnel with the longest excavation mileage using a combination of the two methods in China.

The Tunnel Company of China Railway 18th Bureau Group used the world's most advanced TBM boring machine, which is 180 meters long and weighs 1,800 tons, with an excavation diameter of 10.23 meters, exceeding the height of a three-story building. This is also the railway tunnel currently under construction in China with the largest TBM cross-section and the longest excavation distance.

“The combined use of drill-and-blast and TBM methods not only ensures construction quality and progress, but also ensures construction safety. It can also minimize pollution and impact on the ecological environment from the project and improve the working environment. It marks that under China's special geological conditions, railway tunnel construction technology has reached a world-leading level,” said Su Rui, executive deputy commander of the Lanzhou-Chongqing Railway project of China Railway 18th Bureau.

During the six-year construction of the West Qinling Tunnel, China Railway 18th Bureau Group relied on technological innovation to safely pass through fractured zones of the extra-long tunnel, secondary major faults, high-stress sections and extra-hard rock sections, overcoming technical difficulties such as 20-kilometer single-head ventilation, setting a domestic record for similar tunnel construction with a maximum monthly excavation of 727.7 meters, and achieving more than ten scientific research results and national patents.

The approximately 820-kilometer Lanzhou-Chongqing Railway is an important railway trunk line connecting northwest and southwest China, and an important part of the “Chongqing-Xinjiang-Europe” railway, an international logistics corridor from Chongqing through Alashankou in Xinjiang to Europe. After it is completed and opened to traffic, travel time from Chongqing to Lanzhou will be shortened from the current 21 hours to about 10 hours.