China's "Grand Canal" TBM: The "Iron Dragon" of Underground Construction

China's "Grand Canal" TBM: The "Iron Dragon" of Underground Construction A Symbol of National Strength, Shining Bright Tunnel boring machines (TBMs), often referred to as the "kings of engineering machinery," play a crucial role in the tunnel construction of railway, highway, and subway projects. They are like "iron dragons" that carve through solid rock, showcasing the brilliance of Chinese manufacturing

China's "Grand Canal" TBM: The "Iron Dragon" of Underground Construction

A Symbol of National Strength, Shining Bright

Tunnel boring machines (TBMs), often referred to as the "kings of engineering machinery," play a crucial role in the tunnel construction of railway, highway, and subway projects. They are like "iron dragons" that carve through solid rock, showcasing the brilliance of Chinese manufacturing. From scratch, China's domestically produced TBMs now account for nearly 70% of the global market, with the largest in the world.

"Grand Canal": The "Underground Highway" for the East Sixth Ring Road Reconstruction

The Beijing East Sixth Ring Road Reconstruction project, expected to be completed by the end of 2024, relies heavily on the relentless excavation of the "Grand Canal" TBM. Crafted by China Communications Construction Group (CCCC) specifically for this project, this TBM features self-developed technology and numerous domestically manufactured core components. It holds the record for the largest diameter mud-balance TBM in China, with a diameter of 16.07 meters.

"In the entire East Sixth Ring Road reconstruction project, there's a 7.4-kilometer underground section that's a critical control project, and its construction is undertaken using the 'Grand Canal,'" said L Jiru, project manager of the Beijing East Sixth Ring Road project of CCCC Tunnel Engineering Bureau.

Challenges and Breakthroughs: The Complexity of Underground Construction

Building an "underground highway" is no easy feat. With a maximum depth of 75 meters, traversing through dense water-bearing sand layers and encountering numerous environmental risk sources, the construction demands extraordinary technical capabilities.

"Many people think that tunneling through rivers is riskier, but actually, it's much easier than tunneling through urban areas. The riverbed is less sensitive to subsidence, but in urban areas, even a slight error could cause buildings on the surface to tilt," L explained.

Technological Innovation: Simultaneous Double-Fluid Grouting for Engineering Safety

Facing these challenges, the CCCC Tunnel Engineering Bureau team responsible for the "Grand Canal" TBM construction has relentlessly pursued breakthroughs through continuous exploration. They innovatively applied the synchronous double-fluid grouting technology, which effectively maintains the stability of the stratum, suppresses excessive deformation caused by construction, and significantly enhances tunnel stability and waterproofing.

L expressed his pride: "During the advancement of the 'Grand Canal,' the advantages of the ultra-large diameter TBM synchronous double-fluid grouting technology have become increasingly apparent. Stratum subsidence is controlled within 2 millimeters, tunnel uplift is gradually maintained within 10 millimeters, and the displacement of the formed tunnel is stabilized within 15 millimeters. Leakage control has also reached the 'zero leakage' standard. Moreover, the application of this technology fills the void in synchronous double-fluid grouting for ultra-large diameter mud-balance tunnel construction in China."

Masters of the Craft: Precision Operation Ensures Project Quality

The construction process demands exceptional skills from the TBM operators.

"There's a reason why TBM operators are called masters of the craft. They must not only be proficient in TBM technology but also have a precise understanding of the environment. Operators remotely control the TBM from the cab during daily operations. This process feels like playing a video game and requires

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