"Boom~~" At 10:28 on June 6, with a blast, the last few meters of rock wall on the left line of the Daxiagu Tunnel of the Emei-Hanyuan Expressway were broken through, thus achieving double-tube breakthrough. The Daxiagu Tunnel is a key control project of the Ehan Expressway and is currently the world's deepest-buried expressway tunnel. Its breakthrough marks that the Ehan Expressway has cleared the last "bottleneck," and the full line's opening to traffic by the end of the year has entered the "countdown."

The Daxiagu Tunnel is located in Ganluo County, Liangshan Prefecture, with a total length of 12.1 kilometers. It is an extra-long tunnel, with a maximum burial depth (i.e., the vertical distance from the top of the tunnel excavation section to the natural ground surface) of 1,944 meters. It is invested in by Shudao Expressway Group under Shudao Group and constructed by Sichuan Road & Bridge.

Ye Shaobo, project manager of the Sichuan Road & Bridge Ehan Expressway 2-7 Sub-section, introduced that the Daxiagu Tunnel portal has high terrain, steep slopes, a special geographical location, and complex geological structure. Since construction began in early 2017, various degrees of rockbursts, large karst caves, high ground temperatures, and other geological and environmental disasters have occurred during excavation, among which rockbursts are the most prominent, posing high construction safety risks and extreme construction difficulties.

To break through this "world number one" and bring the expressway to the hinterland of Xiaoliangshan, the frontline project team established a technical research group and a scientific research group, concentrating efforts on studying new processes and new technologies. For rockburst treatment, they invited Feng Xiating, academician of the Chinese Academy of Engineering, and many other well-known industry experts to the site for guidance. Through multiple measures such as installing monitoring instruments for early warning, drilling holes to release stress in advance, and adopting comprehensive measures, they successfully removed the biggest "stumbling block" in the construction process.

"The breakthrough of the Daxiagu Tunnel represents the full breakthrough of the Ehan Expressway." Li Huaming, chief engineer of Leh an Company under Shudao Expressway Group, said that the approximately 123-kilometer Ehan Expressway is being built and opened to traffic in sections. At present, only the Daxiagu Tunnel and the 18-kilometer section at both ends remain unopened, and the full line is planned to be completed and opened to traffic within the year.

The Ehan Expressway crosses towering mountains and connects counties such as Ebian and Ganluo that previously had no expressway access. Its bridge-tunnel ratio is as high as 87.4%, and its construction difficulty ranks among the top in expressways nationwide. The full line is built to a four-lane expressway standard. It is one of the "8 Horizontal" lines in the Sichuan Provincial Expressway Network Plan (2014-2030) and a main corridor of the Greater Emei Transportation-Tourism Integration Pilot Demonstration Zone, connecting five expressways including Chengdu-Leshan, Leshan-Ya'an, Leshan-Zigong, Leshan-Xichang, and Ya'an-Xichang.

"The Ehan Expressway is a major transportation corridor and a major tourism artery," Li Huaming said. The Ehan Expressway links well-known tourist attractions such as Mount Emei, Heizhugou, Daxiagu, and Hanyuan Lake into a line and connects them to the expressway network, which will significantly improve traffic conditions along the route and drive tourism economic development.

After the full line is completed and opened to traffic, it will take only a little over an hour from Emei to Hanyuan, and traveling from Chengdu to Hanyuan will also be more convenient!