On September 16, the Yongfeng Tunnel exit right tube, a key control project of the G544 Shuangjiu Section Highway Reconstruction Project, was safely and smoothly holed through. This is also the first long tunnel to be holed through on the G544 Shuangjiu Road, laying the foundation for achieving the milestone schedule target for the entire line.

The Yongfeng Tunnel is located in Jiuzhaigou County, Aba Prefecture, Sichuan Province, with a total length of 2,988 meters. It is one of the controlling high-risk key projects along the entire line. China Railway No. 4 Engineering Group Co., Ltd. Sixth Company undertook construction of the Yongfeng Tunnel exit section (1,780 meters). The tunnel exit features an end-wall portal, and the tunnel body is a separated two-way four-lane Class I highway, with a main tunnel clear width of 10.25 meters, a clear height of 5.0 meters, and a design driving speed of 80 kilometers per hour.

The Yongfeng Tunnel is located in a high in-situ stress zone. During construction, surrounding rock deformation and convergence were relatively large. The rock is mainly moderately weathered slate intercalated with limestone, with fractured rock masses, alternating soft and hard layers, and well-developed joints and fissures, making construction difficult. "The surrounding rock grade of the Yongfeng Tunnel alternates between Grade IV and Grade V, the surrounding rock changes rapidly, and the tunnel surrounding rock change rate is 58%, which has a relatively large impact on normal tunnel construction," introduced project manager Wang Yongliang. The exit left tube of the Yongfeng Tunnel can have more than 100 construction workers per day, with an average daily advance of 3.6 meters. At present, the left tube of the Yongfeng Tunnel has been excavated 1,586 meters, accounting for about 90% of the total progress, and is expected to be holed through in early November this year.

A relevant person in charge of Jiuzhaigou County Communications Investment and Construction Co., Ltd. introduced that as of now, the overall construction of Section LJ2-2 of the G544 Shuangjiu Section Highway Reconstruction Project is progressing smoothly. Since commencement, a cumulative output value of 405 million yuan has been completed, the tunnel works have reached 85.48%, and the subgrade and bridge works have been completed.

It is understood that the Shuangjiu Road project of the G544 Shuangjiu Section Highway Reconstruction Project has a total length of about 18.71 kilometers. It is a key project of Sichuan Province and Aba Prefecture, and also one of Aba Prefecture's key poverty alleviation projects. It is an important component of the Shuanghe-to-Gonggangling section within the "four horizontal" corridors of the "four horizontal, four vertical, three ring" transportation main framework planned for the Jiuzhaigou County comprehensive transportation hub.