On May 25th, 2025, with the smooth arrival of the "Shui'an-Longyue" rectangular pipe jacking machine into the receiving shaft, the underground passage of the comprehensive utility tunnel project on Longgang Road (from Taohuatan Road to Nanfei River Road) in Hefei City successfully achieved full line breakthrough. This marks the successful completion of the rectangular pipe jacking project under extreme conditions, with an extra-large cross-section and a long distance under the river. The achievement of this significant milestone is not only a major breakthrough in project construction but also another technological milestone in the field of trenchless construction.

The geological conditions of the project are complex, requiring continuous crossing of water-rich sandy layers with low bearing capacity and high permeability. The head pressure reaches up to 0.3 MPa, and the minimum covering soil thickness of the riverbed is only 8.6 meters. The alignment of the tunnel intersects with the pile groups of elevated bridges, with the closest distance being only 1.9 meters. The construction environment is extremely rare in China. The project used the "Shui'an-Longyue" seven-disc earth pressure balance rectangular pipe jacking machine independently developed by Tangxing Technology, with a cross-sectional size of 8.2 meters × 4.5 meters, a single jacking distance of 373 meters, and a total jacking length of 370 meters. Three interjack stations were set up, achieving precise attitude control throughout the process, and the axis deviation was controlled within ±20 millimeters.

To ensure safe and smooth progress, the project team adopted several key technologies, such as soil improvement, attitude control, grouting resistance reduction, and intelligent monitoring. These technologies successfully addressed the challenges of water-rich riverbeds, shallow covering soil, and high jacking resistance. During the river crossing jacking process, the overall average jacking force was about 4,600 tons, successfully achieving the goal of early breakthrough.

The successful breakthrough of this project provides a replicable and scalable technical solution for underground space development under complex urban geological conditions. Tangxing Technology will continue to build intelligent trenchless equipment with high standards and strict requirements, providing solid support for urban infrastructure construction.