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Technology Application in Tunnel Construction Shortens Construction Time

The Quang Ngai – Hoai Nhon Expressway project, part of the North-South Expressway project, is making good progress after nearly two years of construction thanks to the application of modern technology.

One notable aspect of the construction site is the three tunnels that traverse the mountains along the expressway. Tunnel 1 is 610 meters long, Tunnel 2 is 698 meters, and Tunnel 3 is the longest new road tunnel on the North-South Expressway at 3,200 meters.

Currently, Tunnels 1 and 2 have been completed, while Tunnel 3 has been excavated to nearly 3,000 meters out of the total 6,400 meters, with the goal of reaching 5,000 meters by the end of 2024.

Mr. Bui Hong Dang, Director of the Tunnel Project Management Board of the Quang Ngai – Hoai Nhon project, said that the traditional tunnel boring method only allows for one workface in a single space. However, with the new method developed by the Deo Ca Corporation, each workface can be carried out in at least two spaces, helping to speed up progress, reduce machinery and personnel costs, and improve project efficiency.

“This solution is being proposed for application in Tunnel 3 – Package XL3 of the project, with the goal of completing the entire structure in 2025, contributing to the government’s target of completing 3,000 kilometers of expressways by 2025,” added Mr. Bui Hong Dang.

Increasing the number of workfaces and excavation steps not only reduces costs but also improves equipment utilization, saves labor and machinery costs, and shortens the construction schedule by up to four months. It is expected that the second tunnel section alone will save more than VND 40 billion in drilling machine, spraying machine, and labor costs.

Tunnel Construction Invention Granted Form Acceptance by the National Office of Intellectual Property

The invention on a method for constructing road tunnels by increasing the access space and immediately spraying reinforcement after excavation, developed by Deo Ca Corporation, has been granted form acceptance by the National Office of Intellectual Property of Vietnam.

The application will be published in the Industrial Property Official Gazette and undergo a substantive examination to evaluate the possibility of granting a protection title. With the form acceptance, the company has temporary rights over the invention according to the Law on Intellectual Property.

The description attached to the utility solution registration states that this method involves constructing road tunnels by increasing the working space, dividing the tunnel into smaller tunnels, combining inclined mirror excavation, and immediately spraying reinforcement after excavation.

The purpose of this invention is to shorten construction time, save costs, and increase the safety and structural strength of the construction, addressing the limitations of the original design in terms of structural strength optimization.

The method for constructing road tunnels by increasing the access space and immediately spraying reinforcement after excavation includes the following main steps:

Divide the tunnel mirror into two parts: the upper part (the vault) and the lower part (the wall), with the height of each part depending on the height of the drilling machine;

Divide the upper part into two sections, with the first section excavated first with a span of less than 9.5 meters, and the second section excavated after the completion of the first, using multiple workfaces or excavating up to the cross tunnel;

Divide the lower part into three sections, with the first section excavated into multiple workfaces, the second section excavated at once using the horizontal drilling and knot-hole drilling method without detonation, and the third section excavated similarly to the second.

For structures with two parallel tunnels designed with cross tunnels, use the cross tunnel as a passage and divide it into multiple independent tunnels to create additional work spaces.