On June 17, according to Chongqing Construction Engineering Transportation Construction Group, the third extra-long tunnel on the entire Wuyun-Kai Expressway—the left and right tubes of the Dingjia Extra-Long Tunnel—have been fully holed through, meaning the Wuyun-Kai Expressway is one step closer to opening to traffic.

The Wuyun-Kai Expressway has a total length of 118.6 kilometers and a design speed of 80 kilometers per hour. The project starts in Wuxi County seat and ends at Houba in Kaizhou District, connecting with the G69 Chengkou-Kaizhou Expressway. The Dingjia Extra-Long Tunnel is a key control project for the entire line, located from Hongqi Village, Shangba Township, Wuxi County to Fuya Village, Shashi Town, Yunyang County. The left tube has a total length of 4,209.59 meters, and the right tube has a total length of 4,176 meters.

"The tunnel passes through the Damuya anticline structure and is located in the Daba Mountain platform-margin depression area," said Liu Hua, the project's Party branch secretary. The strata along the route are fractured, with small faults and folds developed, and the geology carries disaster risks such as landslides, collapse, sudden mud and water inrush, coal-seam gas, and rockbursts, posing enormous challenges to construction.

To facilitate construction and post-opening operation, the tunnel interior is equipped with 5 vehicular cross passages, 12 pedestrian cross passages, and 1 in-tunnel substation.

How can the geological and rock-stratum conditions ahead be learned in **time during tunnel construction to avoid tunnel collapse?

"We adopted advanced technical equipment and an intelligent digital platform to conduct real-time monitoring of tunnel construction," said the on-site manager.

The project team established a comprehensive safety production management system and built a smart safety and environmental protection management platform. The platform covers 16 modules including a hazard map, safety management index, hazard inspection and remediation, and technical briefings, achieving the management goal of "full data integration, full status visibility, full business manageability, and full event controllability," ensuring the safe progress of tunnel construction.

At the same time, a construction safety "magic tool" was adopted—integrated advanced geological forecasting technology—flexibly using multiple advanced techniques such as the TSP seismic wave method, infrared water detection, and ground-penetrating radar to achieve advance and precise prediction of the geological conditions ahead of construction. The project department also adopted detection methods such as advanced horizontal drilling and deepened blast-hole probing, which helped the project formulate more scientific and precise construction plans.

"During tunnel construction, the project department also actively adopted mechanized construction to replace traditional manual work," said the on-site manager. In tunnel excavation, the project department used advanced technical equipment such as multi-boom rock drilling jumbos, intelligent wet shotcrete trolleys, arch-frame trolleys, and rock-bolt trolleys, greatly improving construction efficiency and quality.

In addition, green construction technologies were actively adopted, implementing "zero-excavation" portal entry and anti-slide pile construction techniques to minimize damage to the original mountain body. In particular, anti-slide piles can effectively prevent landslides and soil erosion, achieving harmonious integration of engineering construction and ecological protection.