Guizhou-Nanning Rail completes construction of riskiest tunnel

The Deqing Tunnel section of the Guizhou-Nanning High-speed Railway completes construction on Aug 3. [Photo/Guangxi Daily]

On Aug 3, the Deqing Tunnel, which was the riskiest for construction of the Guizhou-Nanning High-speed Railway, was successfully completed two months ahead of schedule. It also marked a construction breakthrough for tunnel projects and has accelerated the construction of remaining tunnels along the railway. 

The Deqing Tunnel, located in Hechi city in Guangxi Zhuang autonomous region, has a total length of 6,610 meters, and symbolizes a key project for the railway. The tunnel passes through a typical karst landform area where nearly half of the cave body is surrounded by unstable rock formations. There are more than 200 karst caves in the entire tunnel, which can easily collapse at any time. There are also 2,000 meters of clay pavement in the tunnel with poor bearing capacity and easy to sinking.

The construction team adopted an advanced smooth blasting method, which can eliminate less rock spray and form a flat blasting surface. Meanwhile, the team also used a 3D scanner to collect and analyze rock formation data to effectively ensure the stability of the rock formations around the tunnel. In order to improve the bearing capacity of the clay floor, more than 1,000 pile foundations were laid, and then a strong raft was laid.

Up to now, 85.6 percent of the roadbed earthwork, 81 percent of the bridge engineering, and 78 percent of the tunnel engineering of the Guangxi section have been completed. Tendering and bidding work for high-speed rail construction such as communications, signaling, and power supply will begin in the second half of this year.