China News Service, Hechi, August 3 (Mo Xiaobin, Yang Xuchu, Wei Chenglei) On the morning of August 3, with a loud blasting, the Guinan High Speed Rail crossing the Deqing Tunnel with the highest level of rock formation was successfully completed two months ahead of schedule. It marks that the biggest problem of the tunnel project on the whole line has been successfully solved, and the "fast forward button" is pressed for the end of the remaining tunnels.
Construction workers are using air guns to drill blasting holes.
Photo by Mo Xiaobin
The Deqing Tunnel, located in Hechi City, Guangxi, has a total length of 6610 meters. It is a key control project for the entire Guinan high-speed rail line and the tunnel with the highest level of risk.
The tunnel passes through a typical karst karst landform area. Nearly half of the cave body is surrounded by five-level surrounding rocks with the worst rock stability. Derivative caverns, karst troughs, and dissolution fracture zones can be seen everywhere. On average, there is a karst cave every 50 meters of excavation. , There are more than 200 caves and cavities in the entire tunnel, making the construction difficult.
There are nearly 2,000 meters of pavement in the tunnel, which is a deep clay layer with poor bearing capacity. Improper handling of this marsh-like soil layer can easily cause sinking.
In order to ensure smooth construction, the Guangxi Company of Yunnan-Guizhou Railway and China Railway Second Bureau adopted the most advanced "smooth blasting method" in the construction of high-speed railway tunnels in China.
Compared with the traditional construction technology, the smooth blasting method produces less flying rocks and can form a flat blasting surface. At the same time, it can also use a 3D scanner to collect rock formation data and analyze it in real time. Calculate and optimize the volume data to effectively ensure the stability of the rock formations around the tunnel.
The construction staff carried out air gun operations on the tunnel face.
Photo by Mo Xiaobin
In order to improve the bearing capacity of the clay layer, the construction unit adopted the construction technology of the piled raft structure of the tunnel foundation, laying more than 1,000 pile foundations in the section of the clay layer, and then laying a strong raft.
These reinforced concrete pile foundations and rafts have the characteristics of high bearing capacity and small settlement, which can ensure the safe and stable operation of trains in the future.
The Guinan high-speed railway spans northwestern Guangxi and southeastern Guizhou. It is the first high-speed railway in Guangxi with a design speed of 350 kilometers per hour. It is also an important part of the new land route connecting the north and south of the “Belt and Road”. It is of great significance to construct a new pattern of opening up and development of "south-oriented, north-linked, east-melted, and west-bound".
The whole line is expected to be put into operation by the end of 2023, by which time the travel time from Nanning to Guiyang will be shortened to more than 2 hours.
Deqing Tunnel.
Photo by Mo Xiaobin
Up to now, 85.6%, 81%, and 78% of the total design of the roadbed earthwork, bridge engineering, and tunnel engineering of the Guangxi section of the Guinan High-speed Railway have been completed respectively. Tendering and bidding work for the later stages of high-speed rail construction such as communications, signaling, and power supply. (Finish)