China completes its largest TBM

CREG has completed the development of a 9.3 m diameter TBM, which will bore underneath a mountain in southwest China.

China Railway Engineering Equipment Group (CREG) the tunnel boring machine (TBM) – referred to as the country’s largest diameter gripper hard rock TBM – for the Dianzhong Water Diversion Project in Yunnan Province. 

After being completed at the CREG Deyang Base in Sichuan, China, the 9.83 m diameter Gripper TBM will bore 20.8 km through hard rock at a maximum depth of 1,450 m to create a 26.5 km long water transfer tunnel.

The machine’s total length is 235 m, weighs more than 2,000 t and has a main drive power of 5,600 kW.

A major water resource 

The project is not only considered monumental due to its approval by the State Council of China among 172 other major water conservancy projects, it is also receiving the most investment for a water project in southwest China.  

Upon completion of the project, the tunnel will divert water from the heavy flowing Jinsha River to central Yunnan to provide water for homes and businesses in the region. Additionally, the new tunnel will improve the ecology of surrounding rivers and lakes, benefitting an area of 36,900 km2 and a population of approximately 11.1 million. 

Despite Yunnan in its entirety being known as rich in its water resources, the middle of the province is periodically subject to drought; therefore, it is hoped by officials that this project may avert future water shortages that, in the past, have threatened millions of people and led to billions in lost revenue. 

Challenging geologies

CREG says the rapidly changing geologies in a highly seismic zone, as well as a high rockburst risk, long distance of single direction heading tunnel and high-pressure external water flow, will present several challenges for the TBM.

However, CREG says the TBM and supporting systems have been specifically developed to overcome such difficult geologies, such as the large over-cutting steel arch system with the controlled rock deformation.

This article was featured in the Summer 2020 edition of Trenchless International. To view the magazine on your PC, Mac, tablet or mobile device, click here.

For more information visit the CREG website.

If you have project news you would like featured in Trenchless International contact Managing Editor David Convery at

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