On May 6, China's first triple-mode shield tunneling machine integrating slurry, earth pressure, and hard rock TBM modes, the "CREC 820," launched smoothly on the Luogang–Shuixi section of Guangzhou Metro Line 7 Phase II.

The Luogang–Shuixi section of Guangzhou Metro Line 7 Phase II is 1,086 meters long, with a burial depth of about 19 to 73 meters. The section is densely distributed with full-face hard rock strata, soft soil layers, and upper-soft lower-hard strata. The hard rock strata the shield machine must pass through are about 800 meters long, with an average rock strength of 90 MPa and a boulder detection rate as high as 66.7%. To ensure safe and efficient construction and tunneling of the equipment under complex geological conditions, China Railway Engineering Equipment Group creatively designed and manufactured a triple-mode shield tunneling machine combining slurry, earth pressure, and TBM modes.

The three modes of the triple-mode shield tunneling machine can be switched with one touch according to different strata. Technicians can operate it simply from the main control room without entering the chamber to disassemble and assemble components, greatly avoiding the risks brought by long-term mechanical mode conversion operations. In addition, its smooth muck discharge mode can achieve stepless continuous discharge of rock slag and a dust-free working area, reducing cutterhead and cutting tool wear to a certain extent, and effectively avoiding the surface safety risks caused by the inability to close the earth chamber when encountering sudden water inrush during open-mode tunneling.