On June 27, the left tube of Taohong Tunnel, the first tunnel of the Xuanfu Expressway project invested in and constructed by Yunnan Construction and Investment Group, was successfully holed through, marking that the Xuanfu Expressway project has achieved phased results and laying a solid foundation for the smooth opening of the project to traffic.

Taohong Tunnel adopts a separated-structure design with two-way four lanes; the left tube has a total length of 650 m and a maximum burial depth of 58.8 m. The portal sections have relatively shallow cover, poor surrounding-rock stability, and distributed red clay strata, and the terrain presents a case of biased-pressure shallow cover. The tunnel area has an elevation ranging from 2018.37 to 2094.18 m, with a relative height difference of 75.81 m, and belongs to a tectonically karst-dissolved ridge-and-remnant-hill area and a peak-cluster hilly landform area.

Before tunnel construction, the project company carefully organized all participating units to formulate scientific and reasonable construction plans based on terrain and geology and to optimize construction organization. During construction, the contractor was required to conscientiously implement the design and construction plans, strictly follow the principles of "advance pipe forepoling, strict grouting, short excavation, strong support, early closure, and frequent measurement" to control tunnel construction quality and safety, continuously overcome the adverse effects of complex geological conditions and developed karst and other unfavorable geological conditions, and at the same time strengthen supervision and management of supervision and testing units, fully implement the advance geological forecasting and monitoring measurement systems, and ensure rapid tunnel excavation. In addition, the tunnel construction adopted intelligent video monitoring systems, personnel positioning systems, and other information-based means, further improving the level of safety management. The successful holing-through of the left tube of Taohong Tunnel has laid a solid foundation for the standardized construction and refined management of the Xuanfu Expressway project.