During the Vung mountain tunnel construction, the BOM discovered an anomalous geological zone different from the technical design drawings approved by the Ministry of Transport.

On December 21, 2022, the BOM, Ph.D. Nguyen The Phung - Underground construction professional and representative of PMU 85, design consultant, supervision consultant, and contractor to inspect the geological zone of the tunnel south of Nui Vung (under the Cam Lam - Vinh Hao project ) to evaluate and come up with a solution.

The working group to check the location of the abnormal geological zone

Specifically, at the right tunnel mirror surface (at the explanation Km 123+947.80), there is an underground water circuit (flow rate of about 42 liters/min ~ 2.5 m3/hour), and there is a sand flow phenomenon. According to the technical design, the section is expected to meet an anomalous geological zone about 70m from the current excavation mirror. At the left tunnel mirror surface (at the explanation Km 123+938.10), there is a landslide phenomenon; water flows into large currents, and sand flows. According to the technical design drawings, this location is within the anomalous geological zone.

The BOM has asked the contractor and the consulting unit to supervise both construction and closely monitor the degree of displacement of the supporting structure.

Anticipating the risks, the BOM quickly set up a working group to inspect the scene and invite a professional to find solutions.

After the inspection, all held a meeting to discuss the night. At 10 P.M. on the same day, the working group agreed on six solutions to immediately turn off the displacement of the tunnel structure and drill and dig the next mirrors to ensure the project's progress.

At the meeting, Mr. Ho Dinh Chung asked the construction unit, technical design consultant, and supervision consultant to coordinate immediately deploying the solutions. "This is an unforeseen force majeure factor, but it is also an opportunity for the engineering team to show their capabilities and consolidate experience. The BOM requested the design consultant to coordinate with other units to quickly prepare a dossier to adjust the technical design so as not to affect the construction", said Mr. Chung.

According to Ph.D. Nguyen The Phung, underground works, especially tunnel through mountains, often encounter unpredictable, complex anomalous geological zones. Therefore, special attention should be paid to regular monitoring. At the same time, professional Nguyen The Phung also pointed out points to note in the construction process and required strict control of concrete spraying according to the design to ensure the quality of the work.

BY LAM TRA