On the Quang Ngai – Hoai Nhon expressway, there are 3 tunnels through the mountain: Tunnel 1 is 610m long, Tunnel 2 is 698m long and Tunnel 3 is 3,200m long. When completed, Tunnel 3 will be the 3rd largest tunnel through the mountain in the country, after Hai Van and Deo Ca tunnels.
According to information from Deo Ca Group (the leading unit of the joint venture implementing the first package of the Quang Ngai - Hoai Nhon expressway), up to now, tunnel 1 and tunnel 2 have dug through both branches and basically completed the construction including: concrete tunnel lining, road foundation and maintenance roads on both sides. These works are eligible to deploy finishing items such as road surface and electromechanical equipment. For tunnel 3, the length of the two left and right branch tunnels has been dug simultaneously.
In this project, Deo Ca Group applied many technologies in construction and quality management; especially improving the traditional NATM tunneling method into the Deo Ca NATM method. Accordingly, the technological solution increases the space in construction combined with spraying reinforcement of 1 layer right at the excavation. This is one of the solutions that meets most of the abnormalities encountered in the current road tunnel construction process.
This solution helps bring the structure to a state of equilibrium immediately after excavation for all types of geology. In fact, this solution has been effectively applied in the Quang Ngai - Hoai Nhon expressway project, when the tunnel geology was weaker than the technical design survey. This solution of Deo Ca Group has been approved by the Intellectual Property Office in the form of a patent application in Decision No. 86294/QD-SHTT dated July 18, 2024.
Speaking to Lao Dong Newspaper reporter, Mr. Nguyen Quang Huy - Deputy General Director of Deo Ca Group shared that Deo Ca Group has constructed about 30km of tunnel stretching from North to South. Tunnel construction depends a lot on geology. In the Quang Ngai - Hoai Nhon expressway project, there are changes in geology compared to the design, so during the construction process, the Group has proposed appropriate construction solutions to ensure the quality and progress of the project. Specifically, for tunnel No. 3 with a length of 3.2 km, the sooner the tunnel is opened, the sooner the project will be completed. Therefore, Deo Ca Group aims to open the tunnel 6-8 months ahead of schedule.
With that goal, Deo Ca Group has proposed solutions such as adding more construction heads, combining one-time reinforcement excavation spraying, helping to arrange many construction heads in the same space to shorten the tunnel excavation time. “In Quang Ngai, in the dry season, tunnel construction faces many difficulties in terms of water sources during construction as well as daily life. Deo Ca Group has applied water circulation technology, helping to save 95% of water after construction for reuse in tunnel construction,” said Mr. Huy.
Mr. Nguyen Quang Huy also said that for geological conditions that change frequently, such as tunnel No. 2 with geological changes of about 80%, Deo Ca's improved tunneling method combined with the first reinforcement spraying will follow the nature of NATM tunneling technology, creating a stable structural rock arch right after blasting the opening direction. This technology has helped complete tunnel No. 2 5 months ahead of schedule.
