China's largest slurry tunnel boring machine (TBM) rolls off the production line in Zhengzhou, capital of central China's Henan Province, Sept. 29, 2018. The machine has a diameter of 15.8 meters, making it the largest slurry TBM designed in China. (Xinhua/Feng Dapeng)

ZHENGZHOU, Sept. 29 (Xinhua) -- China's largest slurry tunnel boring machine (TBM) rolled off the production line in Zhengzhou, capital of central China's Henan Province, on Saturday.

TBMs are used to excavate tunnels using a circular cross section that drills through a variety of soil and rock strata, and seamlessly lays concrete segments to produce tunnels, subway tubes and sewer lines.

The machine, named Chunfeng, has a diameter of 15.8 meters, making it the largest slurry TBM designed in China. It weighs around 4,800 tonnes and is 135 meters long.

The machine is developed by China Railway Engineering Equipment Group Co. Ltd. (CREG) and will be used for excavating a tunnel in the southern city of Shenzhen.

"The geological conditions are complex in the tunnel, and the TBM is expected to churn through 3.6 km of rock layer," said Ye Chao, an engineer with CREG's design institute. "We have created special designs to solve the problems and reduce risks. "

CREG is a leading TBM supplier worldwide. As of June, 2018, the company had signed 788 TBMs for tunneling projects, in which 656 are operating around the world, according to the company.