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On May 27, after 640 days, the right tube of the Ping'an Tunnel on the Henan Mianxi Expressway, constructed by CCCC Second Harbor Engineering Co., Ltd., was successfully holed through, laying a solid foundation for the full line to be completed and opened to traffic in 2025.

The Mianxi Expressway starts in the east of Mianchi County, Henan Province, and ends southwest of Zhouzhuang Village in Xichuan County. The project has a total length of 118.387 km. The Mianchi-Xichuan Expressway is divided into the Mianchi-Luoning section, the Xixia-Xichuan section, and the Xichuan-Henan-Hubei provincial boundary section. The subgrade is designed according to the technical standard of a two-way, four-lane expressway.

The Xichuan-Henan-Hubei provincial boundary section of the Mianxi Expressway, constructed by CCCC Second Harbor Engineering Co., Ltd., is 24.838 km long, with a bridge-tunnel ratio of 49%, a subgrade width of 26 m, and a design speed of 100 km/h. It includes 3 tunnels and 28 bridges. Among them, the Ping'an Tunnel is a controlling project for the entire line and is expected to be holed through in both tubes by the end of June this year.

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The Ping'an Tunnel is a separated small-clearance two-way four-lane tunnel in a mountainous expressway section. The left tube is 1,421 m long, and the right tube is 1,420 m long. The maximum buried depth of the tunnel is about 186 m, and the design speed is 100 km/h. The surrounding rock of the tunnel is mainly strongly to moderately weathered dolomitic limestone. Most of the rock mass in the tunnel is relatively fractured, making construction technically difficult and safety risks high.

Since the start of tunnel construction, the project team of CCCC Second Harbor Engineering Co., Ltd. has overcome difficulties such as complex geological conditions, a large workload, and poor road transport conditions. It strictly followed the construction principles of "advanced pipe forepoling, strict grouting, short advance per round, strong support, frequent measurement, and early closure" and adopted technical safeguard measures such as advanced geological radar, geological sketching of the tunnel face, real-time data monitoring, and dynamic adjustment of support parameters, as well as safety safeguard measures such as the in-tunnel video monitoring system, gas monitoring system, and wireless communication system, ensuring the smooth progress of the tunnel.

As one of the first batch of key projects under the "13445 Project" of Henan Province's expressways, the Mianxi Expressway project will, after completion, further improve Henan Province's comprehensive transportation system, promote the formation of the "two rings, eight vertical and four horizontal" road network pattern, improve the overall efficiency of the road network, strengthen economic and cultural exchanges between the Central Plains Urban Agglomeration and the Yangtze River Economic Belt, and enhance development competitive advantages.