Herrenknecht has built a Mixshield tunnel boring machine (TBM) for the construction of a two-storey road tunnel, with three lanes in both directions, in the eastern Chinese city of Jinan.
The Mixshield technology is designed for the extreme conditions of the upcoming undercrossing of the Yellow River and the TBM is currently being dismantled, transported, and then reassembled on the construction site. A machine of this diameter has only been used twice before in the history of tunnelling – the largest was in 2015 in Hong Kong, also a Herrenknecht Mixshield, with a diameter of 17.63m.
The order for the Herrenknecht subsidiary, Herrenknecht Tunnelling Machinery (HTM), in China was a challenging one. The request was for a machine to cross under the Yellow River in Jinan in eastern China, in a geological environment with high groundwater pressure, and to create just one tunnel tube for both directions of travel. A correspondingly large diameter was therefore required – 17.5m over a section of 3.3km.
Jinan is located around 400km south of Beijing and has a population of nine million. It is the capital of the Chinese province of Shandong and an important business location. The road tunnel project to cross under the Yellow River is the second one in 2024 with tunnelling scheduled to begin later in the year. The project aims to improve the connection between the two sides to the north and south of the Yellow River.
Adaptations to the geology
To adapt to the clay, sand and silt geology, and the 7.5 bar groundwater pressure under the Yellow River, a Mixshield TBM was selected. The Mixshield technology developed by Herrenknecht is an advance on conventional slurry technology. The support pressure in the excavation chamber is precisely managed using an automatically controlled air cushion. This means that heterogeneous geologies and high water pressures of more than 15 bar can be controlled safely even with very large excavation diameters. An individual new slurry circuit was designed especially for TBM “Shanhe”.
“We have also equipped the machine with our special telescopic camera in order to better monitor the tool change and the face,” says Herrenknecht’s project manager Zhao Bin, who has already supervised several projects for clients in China. Most recently, he supervised the two TBMs that are also crossing under the Yellow River just a few kilometres away from the new construction site and building a road tunnel with two tubes. The shield diameter of the two Mixshields for the Jinan Jiluo Road North Extension Tunnel project was 15.71m.
Connection for millions of people
Wang Hai is Deputy General Manager of the Herrenknecht office in Beijing and is advising the customer on the challenging project. He says: “Thanks to its efficiency, the new single-tube tunnel supports the national strategy of ecological protection and high-quality development of the Yellow River Basin. It removes a bottleneck of traffic across the river and is calculated to absorb 7.4% of the traffic volume in one go.”
Project data for Jinan Huanggang Road Yellow River crossing tunnel
- Client: Jinan Urban Construction Group Co
- Contractors: China Railway 14th Bureau Group Co.
- Application: Road
- Drive length: 3,290 m
- Geology: Clay, Silty Clay, Sand, Silt, Calcareous Nodules, Glued Sand
Machine Data
- Machine type: Mixshield
- excavation diameter: 17,505 mm
- Cutterhead drive power: 5,600 kW
- Torque: 35,017 kNm
