China's first tunnel across the Yellow River was drilled through in Jinan, capital of Shandong province on Oct 30.
It was the first time that China's largest-diameter highway-railway dual-use shield tunnel was made to go through a perched river on the ground where the river beds are higher than the banks because of sedimentation.
Contracted by China Railway 14th Bureau Group Co., Ltd., a subsidiary of China Railway Construction Corporation Limited (CRCC), the 4,760-meter tunnel has two layers. The upper layer is a two-way six-lane highway and the lower one is for rail transit.
According to Dong Bing, the shielding manager of the project, the section where the tunnel stretches through the Yellow River has a river bed 5 meters higher than the ground on the bank.
The highest flood elevation is 11.62 meters over the ground and the lowest point of the tunnel is 54 meters under the river bed, making it difficult to construct.
The strong water-soil pressure added to the engineering difficulties.
Two slurry balanced shield machines with ultra-large diameters were used for tunneling through the silty clay and long-distance calcareous layer. The greatest rock strength was 45 Mpa, requiring a level of strength equal to that needed to dig through the reinforced concrete pier of a high-speed train railway bridge.
Taking advantage of the underwater shield method and based on big data, Building Information Modeling and the Internet of Things, the engineering team developed safe plans and completed excavation of the tunnel within 11 months.
The western part of the tunnel is now underway.
The profile map of the shielding of the tunnel [Photo/sasac.gov.cn]
(Executive editor: Wang Ruoting)
