Recently, the first permanent magnet driven rectangular pipe jacking machine has been independently developed by CRCHI in Changsha, Hunan, China, with completely independent intellectual property rights.
It is acknowledged that the section of this pipe jacking machine is rectangular. Compared with circular section, its effective area has increased by more than 20%. Therefore, the underground space can be used scientifically. The machine is driven by permanent magnet variable frequency motor, which is small in size and high in efficiency. It is over 5% higher than asynchronous motor of the same power. Besides, it is environmental friendly and energy saving, reducing energy loss of the motors and the temperature in tunneling construction, which is beneficial to stable operation of the whole machine and construction operations.
The machine adopts 6 cutterheads to excavate at the same time. When the project is completed, the drive mechanism of the cutterheads can be refurbished to manufacture 6 small-diameter circular TBMs, to utilize the rectangular pipe jacking machine.