China’s indigenous hard rock TBM of the smallest diameter in the world rolled off the final assembly line at Zhengzhou, Henan province on 27 January 2016. This significant achievement made by China Railway Engineering Equipment Group Co., Ltd (CREG) completed China’s tunneling equipment system.

This is the smallest machine of its kind in the world. The boring diameter of the hard rock TBM is 3.53m and the overall TBM plus the backup is 235m. To arrange millions of parts inside it, its inner structure is quite complicated, which as a result presented plenty of unprecedented challenges regarding R&D and manufacturing.

CREG has come up with a brand new design to enhance the force of the cutterhead, increase the installation accuracy and prevent welding deformation. A dozen of new techniques intensified the rock-breaking abilities and safety factors.

The hard rock TBM purchased by CMC Italia will soon excavate the 23 Km of tunnels in the Greater Beirut Water Supply Tunnel and Transfer Line Project in Lebanon. It is a tailed-design based on the specific geographic conditions of Lebanon.

The present tunneling equipment is already becoming bipolar: maximization and miniaturization. The level of difficulty in techniques is also on the constant increase. CREG is adequately developed in terms of large and medium size tunneling equipments. The small diameter hard rock TBM rolling off the production line fills the gap in the field of micro- and mini types. This movement will open more doors for China’s equipment to go abroad, said Mr. He Fei, the deputy chief engineer of CREG R&D Institute.