First Mountain-Piercing Tunnel on the North-South Expressway
After 10 months of construction, the Deo But road tunnel, the only mountain-piercing tunnel on the North-South Expressway in Ha Tinh province, has achieved a significant milestone as the construction unit completed the drilling of the right tunnel tube from north to south.
The Deo But Tunnel connects Ky Hoa commune (Ky Anh town) and Ky Lac commune (Ky Anh district) in Ha Tinh province. The plan includes two tunnel tubes, with the right tube being 840 meters long and the left tube being 716 meters long. Construction began with the right tube.
The right tube of Deo But Tunnel is now completely drilled. Photo: Ha Tinh Newspaper
In July 2023, Son Hai Group commenced drilling the Deo But Tunnel and mobilized skilled engineers, workers, and advanced machinery and equipment.
The construction unit assessed that the geological conditions at Deo But Mountain were not too complex, which facilitated the construction process. Additionally, tunneling inside the mountain was not significantly affected by weather conditions, so everything proceeded smoothly.
However, while ensuring a rapid progress and the quality of the project, safety remained the top priority for the contractor.
The last few meters of earth and rock at the right tube of Deo But Tunnel were excavated on May 19. Photo: TPO
Thanks to relentless efforts, the 840-meter-long right tube has been drilled. The contractor is now working on waterproofing, concrete pouring for the tunnel shell, and drilling the left tube.
Upon completion, the two-tube tunnel with separate lanes for each direction will enhance traffic safety and reduce project operation costs.
How was the Deo But Tunnel constructed?
The tunnel construction mainly involved rock drilling and blasting. The blasting plan was optimized, with the number of detonators per blast carefully calculated to achieve efficiency without causing vibrations or excessively large blast holes.
The contractor meticulously planned from geological surveys to determine the rock grade, deciding on the blasting method, depth, and amount of explosives. In the past, when blasting, the rock and earth would often collapse significantly, requiring concrete backfilling. However, the design unit has now applied digital technology to optimize the number of detonators.
Additionally, as the work inside the mountain was unaffected by rain and wind, the unit arranged three shifts with four teams working from morning to night. A total of 200 officers, engineers, and workers were involved to achieve the fastest progress.
Modern robot drilling machines and a team of hundreds of workers worked tirelessly 24/7 for the past 10 months.
Overview of Deo But Tunnel. Photo: Son Hai Group
After blasting, iron pipes were inserted into the bedrock, and then workers pumped concrete into the gaps between the rocks and soil to strengthen the tunnel arch. Each tube has two drilling rigs to support drilling and concrete pumping.
During the drilling process, each tube was equipped with a large pipe system to suction dust, reduce noise, and ventilate the tunnel, especially after blasting. Lights were also installed in the tunnel to aid the engineers and workers.
New technology and equipment were also applied in the drilling process, with GPS systems allowing for accurate positioning when drilling from both ends of the mountain, despite the kilometer-long distance. This helped determine if the tunnel alignment was deviating.
A closer look at the construction process at Deo But Tunnel. Source: Ha Tinh TV
The Deo But road tunnel is a component package of the Vung Ang – Bung high-speed project, which is 55.34 km long. The expressway has a total investment of VND 12,548 billion and passes through Ha Tinh (12.9 km) and Quang Binh (42.44 km) provinces. The project is managed by Project Management Unit 6 (Ministry of Transport).
Vung Ang – Bung is one of three component projects of the North-South Expressway in the East Phase 2021 – 2025 being implemented in Ha Tinh province.
According to the plan, the North-South Expressway project through Ha Tinh is expected to be completed by December 2025. However, the Ministry of Transport, the investor, and the contractor are striving to complete the project four to six months ahead of schedule.
When put into operation, the Deo But Tunnel will be one of the highlights of the North-South Expressway section in Ha Tinh.
