Against the backdrop of rapidly advancing underground infrastructure construction, how to cope with increasingly complex underground spaces and reduce interference with existing urban facilities has been a common technical challenge for the industry. On May 25, 2026, the world's first "Dongjin" quasi-rectangular combined pipe jacking-TBM, independently developed by Shanghai, was smoothly launched at the Dongjing Station site of the Civil Engineering Bid 1 for the West Extension Project of Shanghai Metro Line 12. This provides a brand-new engineering solution for overcoming the complex challenges posed by construction in urban core areas intertwined with existing operating lines.
As the "giant among similar types of shield machines," "Dongjin" is the world's largest cross-section earth pressure balance special-shaped cross-section shield machine, and also the world's largest cross-section machine capable of in-ground conversion between pipe jacking and TBM modes. The equipment's external dimensions reach 13530mm × 8438mm, and its massive body carries landmark functionalities never before realized in the field of tunnel construction.
Pioneering "In-Ground Mode Switching" Function
In traditional construction, when a tunnel requires the application of both the pipe jacking method (suitable for short-distance, large cross-section, shallow overburden sections) and the shield method (suitable for long-distance, complex strata sections), a massive intermediate shaft must be set up between the two for equipment lifting, relocation, or switching. Under extremely sensitive conditions like those around Shanghai's Dongjing Station, where there is no space on the ground to excavate a working shaft and the area below sits precisely and directly above the operating Metro Line 9, traditional methods are completely unfeasible.
The "Dongjin" machine's pioneering "combined pipe jacking-TBM, in-ground switching" function solves this problem. The equipment uniquely achieves the function of converting from a "pipe jacking machine" configuration to a "TBM" configuration directly underground without the need for auxiliary shafts. After completing the pipe jacking section, its main system and propulsion system can undergo configuration reconstruction underground, without any lifting or disassembly, directly continuing forward to complete the remaining mileage of the TBM section excavation. This mode-switching function reconstructs the construction process for special-shaped cross-section tunnels at the equipment level, making seamless integration between multiple construction methods a reality.
Large Cross-Section Excavation in Ultra-Sensitive Environments
The equipment's launching point is located directly beneath the operating Metro Line 9, which carries a large volume of daily urban passenger traffic and must ensure "zero interference" with its operation. The earth pressure balance technology adopted by "Dongjin" can utilize the excavated spoil mixed with injected additives to form a "muck chamber" in a plastic flow state during excavation, providing real-time and stable support to the tunnel face. A coordinated real-time intelligent monitoring system enables millisecond-level monitoring of ground surface settlement and existing track deformation.
A Decade of Dedication, Full-Chain Independent R&D of Core Equipment
From early technical research and accumulation in quasi-rectangular shield technology to the launch of the integrated complete machine, Shanghai Tunnel Urban Construction Equipment has completed full-chain independent research and development covering equipment structural design, hydraulic drive, propulsion systems, and intelligent control software.
Far-Reaching Application Prospects
Reshaping the Underground Space Development Model: Construction no longer relies on large-scale land acquisition, demolition, and traffic diversion, which can greatly save precious land resources in urban core areas. Underground space development will be able to easily traverse existing pipelines, historical buildings, and viaduct piers.
Creating a Fast Track for World-Class Underground Transportation Hubs: China is entering a critical period of densifying rail transit, constructing underground high-speed rail stations, and integrating air-rail systems, with rapidly growing demand for complex cross-section tunnel construction. This technology fills the capability gap for efficiently traversing "bottleneck" sections.
Expanding to the Entire Municipal Sector: This construction model also provides a compact, high-quality new paradigm for municipal projects such as urban utility tunnels, power cable tunnels, and water diversion projects facing challenges like shallow burial and close-proximity traversal of existing facilities.
Reshaping the Competitive Advantage of Domestically Produced High-End Equipment "Going Global": The independently developed "Dongjin" machine by Shanghai demonstrates China's systematic engineering innovation capability in the field of super-large cross-section special-shaped boring machines, integrating design, manufacturing, and construction methods. It delivers a Chinese solution for the precise construction of global underground spaces.
The smooth launch of the quasi-rectangular combined pipe jacking-TBM marks a new era for China's super-large cross-section special-shaped tunnel boring technology, characterized by "stop-and-go capability, on-demand deformation, and integration of multiple construction methods." It is a veritable "pillar of national strength" in the field of civil engineering.