On November 6, the reporter learned from Chongqing Expressway Group that the Wulong Tunnel, one of the key control projects of the Yuxiang Second Line Expressway project, has been successfully holed through on both tubes.

The Wulong Tunnel is 6,620 meters long. Its entrance is located near Yonglong Village, Yangjiao Town, Wulong District, and its exit is located in the middle-upper part of the slope on the west side of Changtou River, south of Wulong urban area. The tunnel bore spacing is 40 meters, and the maximum buried depth is about 730 meters. It is a dual-direction six-lane tunnel with a design speed of 80 km/h. It is one of the key control projects of the Yuxiang Second Line Expressway project and also the longest tunnel within Wulong on the Yuxiang Second Line Expressway.

The tunnel is located in high mountains and deep gorges, with steep terrain. The slope at the exit reaches about 75 degrees, with a height difference of 190 meters. The tunnel as a whole passes through karst landforms, with complex geology. Grade IV and Grade V surrounding rock accounts for more than 60%, and karst development is present.

How were the many difficulties addressed? It is understood that the tunnel adopted a two-way heading approach. At the entrance, pipe roofing plus protective arch was used for tunnel entry, while at the exit end a steel platform was built and the double-side drift method was used for tunnel entry.

During construction, the tunnel adopted multiple technological innovations to reduce costs and improve efficiency. For example, the tunnel introduced a full set of mechanized operation modes featuring "one bridge, three machines, and six trolleys," solving the pain points and difficulties of traditional mountain tunnel construction such as high labor intensity, high safety risks, low work efficiency, and poor working conditions, and achieving remarkable results.

For another example, the tunnel introduced a high-precision "Beidou" side and face slope monitoring system to achieve 24-hour all-weather automated monitoring of slopes. It features a high degree of automation, strong anti-interference, and full-process slope monitoring, and is connected with the data of the safety supervision system, improving the intelligent level of major risk handling and effectively enhancing the "technical prevention" level of tunnel construction.

For yet another example, the tunnel introduced 3D laser scanning technology to conduct comprehensive scanning of tunnel excavation, primary support, and secondary lining effects, and to carry out automatic analysis and result evaluation against the design drawings, effectively correcting overbreak and underbreak and improving construction quality.

It is reported that the Yuxiang Second Line Expressway has a total length of 280 kilometers and consists of three sections: Banan to Pengshui, Pengshui to Youyang, and Wulong to Daozhen. The construction period is 6 years, with an average bridge-tunnel ratio of 80%. After the project is completed and opened to traffic, the distance from Chongqing's central urban area to Youyang will be shortened by 47.8 kilometers compared with the current route, and the distance from the central urban area to Yanhe, Guizhou, will be shortened by 79 kilometers. This will effectively alleviate congestion on the Yuxiang Expressway and have far-reaching significance for further developing tourism resources along the route, promoting the integration of transportation and tourism, and driving economic and social development along the route.