Thung Thi tunnel is an item of the construction and installation package No. 12 XL of Mai Son - National road 45 project. The package has a total investment of more than 1,200 billion VND, in which the Thung Thi tunnel is 600 billion VND.
The width of each tunnel branch is 14.5 m, the scale of three motor vehicle lanes
Thung Thi tunnel was started in February. After nearly 300 days of hard working, at the end of November, the right branch of the tunnel was opened, reaching 80% of the excavation volume. The remaining branch has about 80m more, the contractor is expected to drill through in December.
Inside the newly opened tunnel, workers are using a crane to check and reinforce the ceiling before spraying concrete to cover the surface. Advanced Austrian tunneling technology, abbreviated as NATM (New Austrian Tunneling Method), is applied to tunneling by means of explosive drilling, anchor support combined with shotcrete.
According to the approved design, the tunnel is 680 m long, including two branches through a large mountain bordering Ha Tien and Ha Linh communes, Ha Trung district, Thanh Hoa province.
In the middle of the morning, Mr. Nguyen Van Tuan used a hand-held controller to spray concrete on the ceiling surface of the tunnel. This concrete layer will help waterproof and ensure safety for the future operation.
"This is a job that does not require high technology, but it is quite complicated and requires meticulousness," Mr. Tuan said.
The 3-4 m long steel rods are quite heavy, so moving them up requires the concentration of workers.
After his colleague pierced the steel rod through the tunnel arch, worker Nguyen Trong Truong carefully placed the iron gasket and tightened the nut to strengthen the tunnel cover. Today, Mr. Truong is assigned to work in the right tunnel branch with about 40 other people.
Due to the lack of light in the mountain, the construction unit installed many large electric bulbs running along the foot and wall of the tunnel to help engineers work more smoothly and efficiently.
Due to the steep and slippery terrain in the tunnel, all motor vehicles entering and leaving are fitted with a chain system around the wheels to avoid slipping and unsafe.
This is a highway tunnel, so it is bigger than all the road tunnels that have been built before in the province (the scale is one and a half times bigger than normal tunnels). The tunnel ranks third in the entire North-South expressway, behind Lai Vung tunnel and Than Vu tunnel.
Mr. Nguyen Tien Thanh, official in charge of construction of Thung Thi tunnel, said that to ensure the committed progress with the investor, the contractor has mobilized all the most modern machinery and equipment and a team of exprerenced engineers who used to construct many tunnels in Vietnam such as Deo Ca, Cu Mong and Bao Bien... came to work at the construction site.
"We regularly have more than 300 workers, divided into three shifts working 24 hours a day, resting and changing shifts on the spot, so in the tunnel for the past 9 months almost never stopped working", Mr. Thanh said.
This year, due to the complicated epidemic, the contractor minimized the workers' travel and activities, and avoided contact with the outside. "Almost the last 8 months workers have not come home, because if there is a case of Covid-19 disease, it is forced to stop construction and of course greatly affects the progress, so officials and workers strictly abide by it", Mr. Thanh said.
In addition to the tunnel item, package No. 12 also has more than 6 km of roads. Currently, the contractors are leveling, filling the roadbed.
It is expected that in September 2022, Thung Thi tunnel will be inaugurated, but the contractor is striving to finish 3 months earlier.
The North-South Expressway section Mai Son - National road 45 has a total length of nearly 63.4 km, a total investment of more than 12,100 billion VND from public investment. The project includes 5 bidding packages from No. 10 XL to No. 14 XL.
BY LE HOANG
Source: VNExpress