On April 12th, the 14.02m CRCHI TBM ‘New Crossing’ successfully completed boring on the Lot II tunnel section of the Shanghai Airport link line on the city’s first municipal railway.
The Shanghai Airport Link Line Lot II is the key engineering challenge of the entire line, consisting of a shield machine driven tunnel length of 4,939.8m in a single tube configuration to accommodate the double track design. Lot II is now the first large diameter shield machine driven tunnel in China over such a long distance in such close parallel proximity to an existing operational high speed railway line. The minimum distance between the tunnel and the Shanghai-Hangzhou High Speed Railway is just 8.1m. Tunnelling also involved several crossings beneath important structures such as municipal highways, railways and bridges.
As per the characteristics of the project, ‘New Crossing’ was equipped with a number of key technologies such as a normal pressure soft soil cutterhead, a high pressure resistant main drive seal, and an efficient material transportation system which was synchronous with the assembly of prefabricated structures, greatly improving the adaptability and reliability of the machine. With intelligent monitoring systems, the average daily advance of the TBM reached 10.4m. The maximum monthly advance reached 576m, and the monthly advance exceeded 400m for six consecutive months.
The Shanghai Airport Link Line is the first in China to adopt a fully prefabricated assembly system. Faced with the requirements of the large volume of prefabricated components, the large size of each single component, and the high precision requirements of installation and assembly, CRCHI developed a ‘fine adjustment system’ for box culvert and wall assembly, using intelligent one-key assembly with automatic grasping to precisely control the prefabricated box culvert and isolated wall placement. The highest record for installing the isolated wall in a single month was 1200m, a record for the fastest assembly on the whole line.