On May 6, the right-tube entrance section of the Yindianshan Tunnel on Section 8 of the Guizhong Expressway in Guangxi, constructed by China Railway First Group, achieved a single-month drilling-and-blasting excavation advance of over 200 meters, marking a major breakthrough in construction progress and representing the fastest construction progress currently on the Guizhong Expressway.

Tunnel drilling and blasting construction

The Yindianshan Tunnel is a key and difficult project of the Section 8 of the Guizhong Expressway and is a two-way separated tunnel. The right tube is about 5,134 meters long and the left tube is 2,922 meters long. The tunnel passes through unfavorable geological sections such as rockbursts, granite residual soil, and bedrock fissure water; some surrounding rock has developed fissures accompanied by sudden water inflow through fissures. The main tunnel is excavated on a reverse slope and the inclined shaft has a large longitudinal slope, making tunnel ventilation difficult and construction risky and challenging.

Tunnel mucking operation

In the early stage of construction of the Yindianshan Tunnel, the contractor repeatedly used advanced geological exploration to carefully survey the rock formation composition and geological conditions of the tunnel, and also invited relevant experts to conduct technical verification of the construction plan to ensure its final feasibility. During construction, the contractor actively promoted "standardized management and intelligent construction," introducing various new types of intelligent mechanical equipment such as a fully automatic waterproof board installation trolley, a fully hydraulic intelligent partitioned material-distribution secondary lining stainless steel formwork trolley, a new superimposed-arm wet spraying trolley, an intelligently controlled permanent-magnet variable-frequency tunnel-specific counter-rotating axial-flow energy-saving fan, and an L965H side-dump loader, and used a tunnel smart management platform for management, combining intelligent equipment with digital technology. It also innovated the dual-energy smooth blasting technology, which has won the Gold Award of the 5th National Highway Micro-Innovation Competition, effectively improving the control level of tunnel overbreak and underbreak and the excavation quality, shortening the time of the two construction processes of mucking and shotcreting, overcoming the constraints of complex geological conditions, and solving a series of difficulties in tunnel construction, enabling the project to exceed 200 meters of single-month tunnel excavation for the first time and laying a solid foundation for the subsequent breakthrough of the tunnel. As of now, the right tube of the tunnel has progressed 462 meters and the left tube 626 meters.

The Guizhong Expressway is an important component of Guangxi's efforts to accelerate the construction of a highway network that "links the east and leans on the west, goes south and north, connects other provinces and border areas, reaches rivers and the sea, and accesses the entire region," providing transportation support for the stable and relatively rapid economic and social development of Guangxi.