January 27th 2024 saw the 15.4m diameter Slurry TBM “CREC 1398”, designed and manufactured by China Railway Engineering Equipment Group Co., Ltd. (CREG), roll off the production line in readiness for deployment on the world’s largest diameter high-speed railway cross-river tunnel – the Chongtai (Chongming District – Taicang City) Yangtze River Tunnel.
The tunnel has the total length of 14.25km and a maximum depth of 89m with a maximum water and ground pressure of 10.2bar. The slurry TBM will excavate 11.325km under the Yangtze River through fine sand strata, facing a series of technical difficulties such as weak geological conditions, a long tunnel drive through dangerous gases, high water pressures in permeable strata, slurry circulation issues, material transportation challenges, precise control requirements along the tunnel axis, plus ventilation management and safety assurances of post-stage operations.
To deal with the large diameter long distance drive, the high water pressure, the deep overburden and other challenges, CREG has customized the 128m-long Slurry TBM. The wear-resistant performance of key parts of the machine, including the cutter head, the main bearing, and the main slurry discharge pipe have been guaranteed, says CREG, by increasing the thickness of the wear-resistant plates and the quantity of wear monitoring devices. The TBM design has been optimized to ensure that the main drive’s inner and outer seals are able to satisfy the pressure-bearing environment. The explosion-proof ventilation system has been strengthened to ensure it can traverse the harmful gas infused strata smoothly, whilst an intelligent control system, monitoring and warning system have been installed to realize intelligent tunnelling.
The Slurry TBM will be launched in April, 2024. Upon completion, the tunnel will realize the integrated transfer of rail, highway and high-speed rail lines in Chongming making it an important intercity route on the Yangtze River Delta urban development.
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