The world’s largest rectangular tunnel boring machine “Kai Tuo” breaks through at 22:23 on 4th November after a continuous drive for 62 days.
 

The machine (10.42m wide, 7.57m tall) is dedicated to a 92.6m pedestrian underpass at Heiniucheng Avenue, the busiest thoroughfare of Tianjin, linking the exits and entrances at Neijiang Road Station of Tianjin Metro Line 11. It is the largest rectangular tunnel in Tianjin and also the first attempt for Tianjin to adopt super-large section rectangular pipe jacking machine. What’s more, it represents the pioneering practice in China to use rectangular TBM in weak aquifer geology.

A series of technologies & innovations have been applied to “Kai Tuo” by CREG. The three front and three back cutterheads are arranged with parallel shafts and the excavation area of adjacent cutterheads is overlapped. The excavation ratio (excavated area/tunnel cross-section area) can reach 95%. The spoke-style cutterhead with a 70% opening ratio minimizes disturbance to ground and ensures construction security. 

In the second half of the year, CREG is busy with celebration of breakthrough made by several rectangular pipe jacking machines both at home and abroad. On 19th August, “Jiangong” (6.02m wide, 4.52m tall) broke through a 57-meter tunnel undercrossing the South Renmin Road at depth of 5 meters in Chengdu, Sichuan. The machine is the world’s first of its kind applied to cobble sand ground up to this day. On 5th September, another CREG rectangular pipe jacking machine (6.02m wide, 4.32m tall) completed a 29.5m drive in Guangzhou. Following the success of “Jiangong”, the first exported rectangular TBM (7.62m wide, 5.645m tall) of CREG is estimated to complete a 150m underground pedestrian walkway in Singapore in a few days. CREG is now working on an underground parking lot project utilizing rectangular machines right in its Zhengzhou HQ, a novel and bold step to further explore the application scope of the rectangular pipe jacking machine.