On May 9, the "Zhengxian" composite earth pressure balance shield machine successfully passed beneath the Shupu River bed in the Zeya shallow-buried section of the Oujiang River Water Diversion Project, reaching its predetermined position and achieving tunnel breakthrough.

The railway-related section of the Oujiang River Water Diversion Project totals 6.7 kilometers and is the contract section with the most complex geological conditions, the most risk sources and construction techniques, and the greatest safety and technical challenges in the entire project. The tunnel in the Zeya shallow-buried section was constructed using the shield method. Traversing 9 geological changes, the project team drove the shield through complex strata including water-rich permeable gravel, cobble, boulder and isolated-rock formations and extremely hard rock, passing beneath risk sources such as the Shupu River and the Zhou'ao Grand Bridge of the Jinhua-Wenzhou Railway at a clearance of one tunnel diameter. Through technical research, the team innovatively applied techniques such as "freezing method" ground reinforcement, balanced shield mud chamber establishment, the Samson life support system, dynamic optimization of cutter physical performance design, and in-tunnel equipment disassembly and reception, solving the safety and technical challenges of shield tunnel engineering under complex environmental conditions and giving full play to the prominent role of new quality productive forces in the engineering construction phase.

The cutterhead of the "Zhengxian" shield machine has a diameter of 6.47 meters, and the entire machine is 85 meters long, consisting of the main shield and 6 trailing "gantry" cars. Each gantry car has its own unique system functions, combining the operator cabin, synchronous grouting system, secondary grouting system, water circulation system, and belt conveyor mucking, with a total weight exceeding 500 tons. To ensure the safe, stable and efficient advancement of the "Zhengxian" shield machine, the project team established a scientific research task force, organized industry expert teams, carried out innovative technical research, and formulated scientific and feasible construction plans. They adhered to dynamic hazard source management and acceptance of hazardous major procedures, implemented safety measures such as leadership shift supervision and emergency support, and safely organized 11 chamber operations (400 chambers) (including hyperbaric chamber entry operations beneath the Shupu River bed). Working "5 plus 2, white plus black," they completed the breakthrough of the railway-related tunnel in the Zeya shallow-buried section in 365 days.

It is reported that since construction began in June 2022, the railway-related section of the Oujiang River Water Diversion Project has completed a cumulative 6,247.26 meters, accounting for 92.56% of the total design quantity, creating favorable conditions for achieving full-line breakthrough of the Oujiang River Water Diversion Project this year.