Recently, new progress has been made in the construction of the Luoze River Grand Bridge and the Binghui Tunnel of the Chongqing-Kunming High-Speed Railway, both located in Yiliang County, Zhaotong City. The pile cap of Pier No. 3 on the critical route of the Luoze River Grand Bridge was completed on May 6, and the right-line main tunnel from the No. 2 inclined shaft to the exit section of the Binghui Tunnel, the second longest tunnel on the Chongqing-Kunming High-Speed Railway, was successfully holed through on May 8, laying a solid foundation for the smooth advancement of subsequent works.

The Luoze River Grand Bridge, constructed by China Railway Major Bridge Engineering Group, is 524.9 meters long and located in Yiliang County, Zhaotong City. It is designed with separate left and right lines, with its main span crossing the Luoze River. The terrain on both banks is steep and the geological conditions are complex. The pile cap of Pier No. 3 of the Luoze River Grand Bridge poured this time has a designed length of 43.7 meters, a width of 21.3 meters, and a height of 6 meters.

To address the problem of temperature cracks caused by hydration heat and shrinkage during the mass concrete construction of the pile cap, the Chongqing-Kunming Project Department of China Railway Major Bridge Engineering Group adopted a concrete internal temperature acquisition system, installing temperature sensors and a pipe cooling system inside the concrete to monitor the concrete temperature field in real time and adjust the pipe cooling system, thereby preventing cracks inside the concrete and ensuring the construction quality of the pile cap.

To accelerate the construction progress of the Luoze River Grand Bridge, the main girder is planned to be constructed using a large-segment intelligent bridge-building machine, with a maximum segment length of 6 meters and a segment weight of 330 tons. Compared with the traditional 4-meter segments, the adjusted scheme substantially reduces the number of segments and effectively speeds up construction progress. Moreover, during use, operations such as traveling, anchoring, formwork removal, and protection are more intelligent, informatized, and systematic, with high safety, significant research value, and a leading and demonstrative role for the industry.

The Binghui Tunnel, the second longest tunnel on the Chongqing-Kunming High-Speed Railway, constructed by China Railway No. 5 Engineering Group, is located in Yiliang County, Zhaotong City, with a total length of 21.17 kilometers. It combines a series of unfavorable geological conditions such as water inflow, karst, large deformation of soft rock, and fault fracture zones, and is a Class I risk tunnel and a controlling project of the entire line. The right-line main tunnel from the No. 2 inclined shaft to the exit section of the Binghui Tunnel holed through this time has a total length of 5,047 meters.

Since construction began in April 2022, the Party Working Committee of the project department has focused on the theme of high-quality construction, anchored to the schedule targets, made careful deployments and arrangements, and deepened core controls in safety, quality, and construction organization. Mechanized supporting construction was adopted during the construction process, with the maximum monthly advance exceeding 142 meters. By optimizing the ventilation scheme and selecting Yutielong variable-frequency fans, the air volume requirements throughout the operation were ensured, and the promotion and application of processes such as shaped-charge hydraulic blasting and longitudinal continuous grouting improved the project quality.