Hard Rock Rectangular Pipe Jacking Machine Breaks New Ground in Chongqing

In a groundbreaking development for infrastructure engineering, the world’s first hard rock rectangular pipe jacking machine, named CREC 1112, has successfully completed a major project in Chongqing, China. Developed and manufactured by the China Railway Engineering Equipment Group (CREG), this advanced machine has achieved a significant breakthrough on the pipe jacking section of the N-Standard-Partition Street Interchange C-Traffic-Node A-Ramp project in Chongqing Liangjiang New Area.

A Revolutionary Advancement in Pipe Jacking Technology

The CREC 1112 machine represents a leap forward in the field of tunnel construction. This innovative machine is the first large cross-section rectangular pipe jacking machine to complete a full-face excavation in hard rock strata, addressing the longstanding challenge of blind area excavation. With dimensions of 10.42 meters in width and 7.57 meters in height, it is equipped with six circular cutterheads and six drum cutters, ensuring the entire tunnel face is covered during excavation.

Engineering Precision and Customization

The CREG team tailored the machine's systems to enhance its rock-breaking capabilities and tunneling performance while minimizing ground disturbance. This was particularly crucial given the tunnel's path beneath two, two-lane roads with a shallow overburden of only 4-5 meters. To manage these challenges, the machine was outfitted with three intelligent systems for remote control: the intelligent thrust system, the soil conditioning system, and the friction reduction system. These systems allow for precise control of the cutterheads and shield articulation cylinders, real-time adjustment of the advance direction, and dynamic monitoring of muck and friction reduction materials.

Efficiency and Safety Improvements

The CREC 1112 has a maximum monthly advance rate of approximately 30 meters, which significantly reduces the construction period by about half compared to traditional hand excavation methods. This advancement not only slashes labor costs by 60% but also enhances construction safety. The successful operation of this machine on May 15, 2024, marked a milestone in the use of large cross-section hard rock rectangular pipe jacking machines, setting a new standard for similar projects worldwide.

Project Impact and Future Implications

Linking Lushan Avenue near the North Square of Chongqing North Railway Station with the Chongqing Inner Ring Expressway, the project required navigating complex underground conditions. The machine's ability to perform under these conditions without significant ground disturbance is a testament to its advanced design and engineering. The successful completion of this project underscores the potential of the CREC 1112 to revolutionize tunnel construction, particularly in challenging geological environments.

The breakthrough achieved by the CREC 1112 fills a critical gap in construction technology, offering a robust solution for future infrastructure projects involving hard rock and complex urban settings. As the first machine of its kind to accomplish such a feat, it paves the way for more efficient, safe, and cost-effective tunneling operations around the globe.

The video below demonstrates the operation of Rectangular Pipe Jacking Machine (subtitles in English).