KUNMING, Oct. 12 (Xinhua) -- The Bailazhai defect treatment project on the Nanning-Kunming high-speed railway, undertaken by China Railway 25th Bureau Group Co., Ltd., has completed all manually excavated piles, according to China Railway Construction Corporation Limited (CRCC) on Monday. The completion marks a key breakthrough in the defect treatment project and lays an important foundation for ensuring the operational safety of the high-speed railway.
The Nanning-Kunming high-speed railway opened to traffic in 2016. It is an important high-speed rail corridor linking Yunnan and Guangxi, a key part of the New International Land-Sea Trade Corridor, and an important transport support for Yunnan's opening-up to South and Southeast Asia. Affected by complex plateau and mountainous geology, many sections of the railway face geological weaknesses. Railway authorities have persisted in regular inspections and phased remediation of hidden dangers. The special defect treatment at the Bailazhai bridge area is an important part of improving the safety of the entire network and enhancing disaster prevention and mitigation capabilities.
The two four-track bridges at Bailazhai under treatment are located in Guangnan County, Wenshan Prefecture, Yunnan Province, on the southeastern edge of the Yunnan-Guizhou Plateau, with steep mountains and severely weathered rock. Long-term rainwater immersion and slow soil displacement have caused local deformation and loosening of slopes and gullies in the bridge area, posing safety hazards to the regular operation of the high-speed railway and requiring special reinforcement to eliminate risks.
"The project is adjacent to an operating high-speed railway, making it a refined remediation project with high standards, many constraints and dense risks. On-site control is far more difficult than ordinary mountain construction," said Zhang Peng, project manager of China Railway 25th Bureau.
Given the risks and challenges of being close to an operating high-speed railway, difficult hole formation in fractured rock and ecologically sensitive mountainous areas, the project team strictly followed operational line regulations, fully equipped protection personnel and equipment, and relied on an automated monitoring system to monitor tracks, lines and communication equipment in real time, strictly preventing construction vibration from interfering with high-speed rail operations. To address the problems of easy hole collapse and deviation in manually excavated piles in fractured rock strata, the site adopted a construction method combining wall protection reinforcement, combined support and dynamic monitoring, steadily advancing hole forming and pouring operations and solidly consolidating the foundation for slope support. At the same time, builders strictly observed the ecological red line in mountainous areas, properly handled construction spoil and strictly controlled the scope of construction disturbance to maximize protection of the ecological environment along the line.
During construction, the project team actively carried out technical research. Its independently developed "manually excavated pile hanging basket" was successfully granted a national invention patent, accumulating mature and practical construction experience for similar defect treatment projects near operational lines in southwestern mountainous areas.
Manually excavated piles are a core fundamental procedure for slope reinforcement and geological hazard treatment. The smooth completion of this key milestone has effectively reinforced the slope soil structure in the bridge area, resolved local geological hazards in this section, and significantly improved overall slope stability and the section's disaster resistance. As an important phased achievement in the regular safety improvement of the Nanning-Kunming high-speed railway, the project will continue to ensure the safe and smooth operation of the Yunnan-Guangxi transport corridor, safeguard travel safety for people along the line, and provide solid transport support for border stability, rural revitalization in Wenshan and high-quality opening-up and development in Yunnan.
