The largest tunnel boring machine (TBM) of its kind, a machine with a diameter of more than 7 m (23 ft) rolled off the production line on in Changsha, Hunan province.
China Daily reported that the TBM was produced by China Railway Construction Heavy Industry Corp and China Railway 18th Bureau Group Corp, the machine is about 100-m (330-ft) long. It can achieve a horizontal turning radius of 200 m (660 ft), and a vertical curve radius of 380 m (1,246 ft) of tunneling.
As the first large-slope tunnel-boring machine in the world, the so-called Beishan No 1 will be used in the construction of an underground laboratory to research disposal technologies for high-level radioactive waste in Beishan, Gansu province.
The machine will excavate a spiral curve slope in Beishan, about 7.2 km (4.5 miles) long. With each 10 m (32 ft) of excavation, the working height of the machine will drop 1 m (3 ft).
The landscape in Beishan consists mainly of granite, a type of hard rock, making work more challenging, said Xu Chunxian, head of the Beishan construction team from China Railway 18th Bureau Group Corp.
The design of the cutting head of Beishan No 1 has a rock breaking efficiency three times that of a machine with a traditional plane cutter head, said Wu Min, vice-president of the TBM design institute of China Railway.
The design team improved the space structure of the machine, coupled with advanced guidance, direction control and an automatic cruising system to assist driving and increase the flexibility of the machine in cutting large-slope spirals.
Photo credit: CCCME.