According to media reports on November 9th， the Yinjiang Buhna project has achieved a significant milestone: the successful excavation of the No. 6 horizontal tunnel， the longest auxiliary tunnel on the entire line. After 307 days of continuous construction， the “Jianghan Ping’an Hao” TBM (Tunnel Boring Machine) precisely reached the main tunnel working face. This horizontal tunnel measures a total of 3，887 meters in length.
As a follow-up water source project for the Middle Route of the South-to-North Water Diversion Project， the Yinjiang Buhna water transmission project is a key component of national strategic water network construction. It stands as the longest， largest diameter， and highest flow rate long-distance pressurized water diversion tunnel currently under construction in China， with a total transmission line length of 194.7 kilometers.
During the construction phase， the “Jianghan Ping’an Hao” encountered complex geological challenges， characterized by “three highs and four mosts”: high ground stress， high external water pressure， high rock strength， and multiple faults， rock types， and geological hazards. The project team innovatively established an integrated response mechanism involving “geology—equipment—personnel.” Leveraging a digital twin platform and the TBM-SMART intelligent monitoring and intelligent decision-making system for pre-drilling， the team was able to accurately predict and dynamically control fault fracture zones， rockburst risk areas， and high-pressure water inrush zones， ensuring the safety and controllability of the construction process throughout.
Notably， when traversing a 7.1-kilometer section of extremely hard rock， the team meticulously optimized aspects such as cutter selection， cutter ring material， geometric shape， and heat treatment processes to address conditions with rock hardness up to 300 MPa. These optimizations significantly enhanced the durability and replacement efficiency of the cutters， ensuring the continuity of excavation.
By deploying multi-stage pumping stations and utilizing techniques such as pre-grouting， the project team effectively managed the risks of high-pressure water inrush and improved the stability of the surrounding rock. This enabled the TBM to successfully navigate multiple high-risk geological sections， setting a record for the first excavation of over 1，000 rings on the entire line. Furthermore， it continuously broke the monthly footage record for a 12-meter-class double shield TBM， achieving a maximum daily excavation of 31 meters.
The Yinjiang Buhna project is the first major project to commence construction among the follow-up projects of the South-to-North Water Diversion. Upon completion， it will significantly enhance the water transfer capacity from the Yangtze River to the north， improve the supply guarantee rate of the Middle Route Project， alleviate water supply-demand conflicts in the Han River basin， and improve the regional water ecological environment， thereby realizing the inter-basin connection between the Yangtze River， Han River， and North China.
