On the afternoon of August 24, the Hangtianyuan Tunnel of Section 1 of the Wangjia Dajing Water Source Emergency Replacement Project in Guiyang was successfully holed through, laying a solid foundation for the smooth completion of the project and pressing the accelerator key for water supply across the entire line.

The starting and ending points of the Hangtianyuan Tunnel are located at Jianshan in Huaxi District—the intersection of Zhongtong Road and Kaifa Avenue, with a designed water supply capacity of 300,000 cubic meters per day. The tunnel has a total length of 1,478.8 meters. The geological conditions are complex, belonging to typical karst landforms, with undulating terrain. It passes through the urban core area, where the surrounding environment is sensitive, the rock stratum strength varies from soft to hard, the stability of the surrounding rock is poor, and the construction safety risk is high.

In addition, the Hangtianyuan Tunnel successively passes beneath the internal road of Gaokaisi, the city's main road Kaifa Avenue, the residential area of a confidential unit of China Aerospace Science and Industry Corporation, the Xiaohuang River, and areas adjacent to the Nanming River, among other major construction difficulties. The surrounding construction environment is extremely complex, and the construction risk is high.

The Guiyang Wangjia Dajing Project actively coordinated all participating parties to conduct precise analysis and comprehensive assessment of the above major difficulties. It used professional methods such as advanced drilling, ground-penetrating radar, elastic wave reflection, and transient electromagnetic methods, combined with scientific technologies such as face curtain grouting, surface curtain grouting, and monitoring and measurement. It adopted the "short, tight, fast, and diligent" mode as well as related measures such as relay fan ventilation and integrated excavation and support construction by roadheader. In process control, it adopted dynamic design and information-based construction, promptly optimized the excavation and support scheme, and overcame difficulties such as passing beneath the urban core area, karst development, asymmetrical loading and shallow cover, large differences in surrounding rock hardness, difficulty in protecting surface roads and buildings along the line, groundwater development, and large water inflow during the rainy season. This ensured that each procedure met the design requirements and achieved the expected goal of "zero accidents."