Recently, as the main unit of the pipe-roof machine was nondestructively retracted from within the pipe sections, it marked that the retractable pipe-roof machine jointly developed byCRCHI (China Railway Construction Heavy Industry)and China Railway 25th Bureau Group successfully helped complete the first section of China's first pipe-roof project crossing beneath a high-speed railway subgrade.

It is understood that this pipe-roof project requires passing beneath an operating high-speed railway line and is a key part of the traffic culvert project on Hedong Central Road, Dali Town, Foshan City, where it passes beneath the Sanyanqiao Station on the Guangzhou-Maoming line. The pipe roof is about 4 meters below the track bottom and consists of 72 steel pipes of 900 mm diameter. The strata consist of backfill soil and crushed stone, with reinforced concrete piles present. The project has extremely high settlement-control requirements and is extremely difficult to construct.

Pipe-roof machine construction site

To meet the challenges of this complex project, CRCHI developed a retractable pipe-roof machine. The equipment has an excavation diameter of only 940 mm, effectively controlling strata disturbance and making it possible to build a large tunnel with small equipment. The main unit has an efficient, nondestructive retraction function inside the tunnel; through the automatic retraction system, the main unit can be quickly dragged back to the launch point without personnel entering the tunnel.

Pipe-roof machine retraction

The equipment is equipped with a step-changing propulsion system that enables efficient single-pass advancement of 23 meters. In the first section, it excavated about 7.6 meters within 2 hours and successfully cut through reinforced concrete piles along the route. At present, nondestructive retraction of the equipment and rapid launch of the second section have been completed.

Photo of rebar cutting

After the project is completed, it will effectively connect the cross-railway passage on Hedong Central Road in Dali Town, accelerate the northward extension of the Nanhai urban axis, build a 15-minute living and working circle in the Guangfo Bay area, and establish a road network structure of "nine vertical, five horizontal, and one ring." It is of great significance for opening up the major artery of "crossing the river and entering the bay" and optimizing the regional road network and traffic layout.