China’s Largest Hard Rock TBM Ready for Dianzhong Water Diversion Project

On May 8, 2020, China’s largest diameter (9.83-m) gripper hard rock tunnel boring machine (“Yunling”), which was independently developed by China Railway Engineering Equipment Group Co. Ltd. (CREG), successfully rolled off the production line at CREG Deyang Base in Sichuan, China. The machine will be used for the Dianzhong Water Diversion Project in Yunnan Province.

The Dianzhong Water Diversion Project is not only a landmark project approved by the State Council of China among the 172 major water conservancy projects, but also the largest and most invested water resource allocation project in Southwest China. Dali Section I Lot 3 is a key part for the whole tunnel project. The main tunnel is 26.542 km long, among which 20.802 km is excavated by hard rock TBM. This project has various features and difficulties, such as rapidly-changed geology of the surrounding rock; long distance of single direction heading tunneling and continuous shallow buried depth; extremely long distance of the single direction heading ventilation; high ground stress, external water pressure and seismic intensity; active groundwater environment and large faults.

As China’s largest gripper TBM, “Yunling” is customized for the Dali Section I Lot 3 of the Dianzhong Water Diversion Project. The total length of the machine is about 235 m, the total weight is about 2,050 tons and the main drive power is 5,600 kW. It is equipped with four 17-in. twin disc cutters, 57 19-in. disc cutters which can also be changed to 20-in. disc cutters. The TBM can expand up to 30 cm in diameter at the maximum and can install steel slats in the top 270°. It is equipped with an L1 area automatic emergency wet shotcreting system, a 360° probe drill system, a geological prediction system, a harmful gas detection system and an emergency refugee chamber, etc.

After the completion, the project can divert water from Jinsha River main stream with relatively abundant water to the central Yunnan, providing water for production and living in some towns and cities in central Yunnan, improving the ecology of rivers and lakes in this area and benefiting an area of 36,900 km2 and a population of 11.12 million.

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