China self-innovated TBM is first such export to Sri Lanka

China's first tunnel boring machine (TBM) of indigenous innovation at China Railway Construction Heavy Industry Co Ltd in Changsha, Central China's Hunan province. [Photo/sasac.gov.cn]

China's first tunnel boring machine of indigenous innovation to be exported to Sri Lanka recently passed an acceptance inspection at China Railway Construction Heavy Industry Co Ltd  in Changsha, Central China's Hunan province.

The TBM will be transported to Colombo, capital of Sri Lanka, after China's Lunar New Year.

The diameter of the TBM is only 3.7 meters, smaller than common ones which have diameters from six to more than ten meters. The TBM will be used to construct the New Mutwal and Torrington drainage system.

The small TBM includes all the parts that larger ones should have, such as a cutter and shield and mechanical, electrical and hydraulic pressure systems.

The TBM's functions are therefore the same as large ones, although its diameter is the shortest among all current China-made earth pressure balance shield machines. The main parts of the TBM have been tailored in accordance with its small layout, said Zhang Ruilin, chief designer of the shield machine.

Zhang said that the TBM, although smaller, can overcome difficulties that common shield machine can't tackle. It can break rocks with a hardness of 150 Mpa which is same as holding 15 adult elephants with one hand, and it can keep working with a minimum turning radius of only 80 meters, while the common TBMs can't work if the turning radius is less than 250 meters.

The China-made TBM has technological innovations. Its cutter and screw conveyer are protected from wear and the cutter also can withstand strong shocks.

Zhang said that the TBM is equipped with a control room and workers' cabin designed according to sedan space standards to ensure safety and comfort.

The Sri Lanka government launched international bidding to construct the New Mutwal and Torrington drainage project to improve its capital's old sewage system which is not able to discharge in floods. Sri Lanka is an island country on the Indian Ocean and an important pivot along the Maritime Silk Road. The central part of the island has lots of mountains but coastal areas are lowlands which flood in the rainy season when rainwater flows to them from the mountains.

The construction will be carried out by China Petroleum Pipeline Engineering Co Ltd and the equipment needed in the construction will be exported from China Railway Construction Heavy Industry Co Ltd. The TBM will begin work in April of 2019.

(Executive editor: Li Shuling)