Rectangular Pipe Jacking Machine Used for Constructing 3‑Lane Highway Tunnels

The project involves an urban highway tunnel featuring six lanes in two directions, with a single tunnel length of 100.5m. According to the project requirements, the rectangular pipe jacking machine (CREG 798) is designed with an excavation size of 14.82m×9.448m. It features a multi‑head combined excavation design, utilizing 6 front cutter heads and 8 rear heads along with an optimized shield section design. This configuration enables one‑time excavation and formation, while effectively managing the main machine's attitude and ground settlement during the construction of super‑large‑cross‑section rectangular pipe jacking projects. Key advantages of this machine include minimal traffic disruption, reduced environmental impact, and enhanced safety and efficiency during operation. During the construction process, a maximum daily advance rate of 4.5m was achieved, with a total duration of 4 months from the launch of the project to the breakthrough.

Project Background

This project marks the pioneering successful application of rectangular RPJM technology in the construction of a 3‑lane rectangular tunnel. For an extended period, CREG has prioritized the research and development of rectangular pipe jacking machines. The project titled "Key Technologies and Applications for the Design and Manufacturing of Non‑Circular Full Face Tunnel Boring Machines," led by CREG, was awarded the second prize of China's National Science and Technology Progress Award in 2018. To date, CREG has designed and manufactured over 30 rectangular pipe jacking machines, which are widely employed in the construction of urban highway tunnels, underpass roads, utility tunnels, underground parking lots, and various other applications. These innovations have established CREG as a leader in technological advancement in the field of underground space development, contributing significantly to the construction of urban underground infrastructure.

Underpassing Nanhu Avenue Project Route in Jiaxing City

A super‑large pipe for the three‑lane highway tunnel is being lowered into the shaft.

Successful breakthrough of the super‑large cross‑section rectangular pipe jacking machine.