On September 15, the first tunnel of the Suzhou Xutao Road–Hengshan Road Tunnel Project, an extra-large cross-section rectangular pipe-jacking underpass and Suzhou's first passage beneath the Beijing-Hangzhou Grand Canal, was successfully completed by the China Railway Shanghai Engineering Bureau. This marks the successful connection of the "dead-end roads" on both banks of the Grand Canal, opening up a convenient route for local residents.

According to Ji Hongxin, chief engineer of the Xutao Road–Hengshan Road Tunnel Project of the China Railway Shanghai Engineering Bureau, the underpass project adopted rectangular pipe-jacking technology, marking the first domestic application of this technology beneath the Beijing-Hangzhou Grand Canal. During actual construction, the rectangular pipe-jacking technology ensured the normal operation of the waterway while avoiding damage to the Grand Canal's water quality and environment, thereby protecting the historical appearance of the Grand Canal as an intangible cultural heritage site.

The pipe-jacking underpass has a cross-section 9.8 meters wide and 5.9 meters high, and presented construction difficulties including long-distance crossing beneath the main navigation channel, shallow cover soil above the riverbed, and settlement control of the underwater bottom surface. With complex geological and hydrological conditions, the construction difficulty, cross-section size, and jacking length of this underpass represent the largest for a municipal vehicular tunnel built by rectangular pipe-jacking in China.

To solve the huge friction resistance problem caused by the long distance, the project team closely monitored the real-time jacking force of the hydraulic cylinders, the soil pressure of the cross-section, and the motor current, and conducted comprehensive analysis against theoretical values. Based on field geological conditions, they tested and prepared friction-reducing slurry, and injected the slurry and dense mud through grouting holes arranged inside the pipe segments to form a mud sleeve around the pipe segments. Before the pipe segments were lowered into the shaft, their outer walls were coated with wax and baked to reduce the friction coefficient between the pipe wall and the soil, thereby reducing friction resistance. At the same time, the jacking speed and the operation time of each construction step, such as pipe segment installation, were reasonably controlled to ensure continuous and balanced jacking construction and avoid prolonged suspension.

Crossing beneath the shallow-cover waterway was the greatest challenge of the project. The project team treated the first 10 meters of jacking as a test section, comprehensively summarizing and analyzing data such as jacking construction parameters, jacking axis, pipe-jacking machine attitude, the soil discharge capacity of the screw conveyor, and ground deformation, so as to improve the construction parameters. During the actual underpass, they strengthened control of the pipe-jacking machine attitude and construction axis. Meanwhile, they set up an innovation studio for rectangular pipe-jacking construction to tackle technical difficulties such as friction reduction in large-cross-section long-distance pipe jacking and ground settlement control. They collected more than 5,000 items of construction data, accumulating valuable experience for subsequent pipe-jacking construction and even for large-cross-section long-distance rectangular pipe-jacking beneath rivers with shallow cover soil and for continuous jacking construction in severe weather, making the large-cross-section long-distance rectangular pipe-jacking construction technology more complete and mature.

It is reported that the Xutao Road–Hengshan Road Tunnel Project is expected to be fully completed by the end of this year. Upon completion, it will connect the "dead-end roads" between Hengshan Road and Xutao Road, link Gusu District and the High-tech Zone, ease traffic pressure across the Beijing-Hangzhou Grand Canal between the two districts, and greatly facilitate travel for people on both banks of the Grand Canal.