The first domestic super-large diameter shield machine with normal pressure tool change successfully crossed the river-State-owned Assets Supervision and Administration Commission of the State Council
On June 1st, the first domestic super-large diameter slurry balance shield machine "Yuan ‘an" successfully crossed the Yuanjiang River in Changde, Hunan Province, marking the end of the river bottom project of the largest underwater shield tunnel in Hunan Province-Changde Yuanjiang River Crossing Tunnel. This is also the first time that the atmospheric tool changing technology has been successfully applied to the domestic shield machine.
The excavation diameter of the equipment is 11.75 meters, and the length of the whole machine is 132 meters. It is jointly developed by China Railway Construction Heavy Industry and China Railway 14th Bureau. Because the cutter head looks like a blooming peach blossom, it was praised by the media as "the most beautiful shield machine in history" when it was born last year.
Not only is the face beautiful, but also the "kung fu" is high. The equipment was launched at the end of December last year, and the strata it passes through are silty clay and round gravel, which are rich in water content and have the characteristics of high formation strength, high permeability coefficient and high water pressure. Especially in the shield section of Jiangbei levee, the geology is more complicated, and a series of unexpected situations, such as mud cake on cutter head, blockage of central flushing pipeline, and sudden surge of groundwater, are prone to occur during construction.
According to Zhang Keqiang, service manager of Changde Yuanjiang Tunnel Project of Railway Construction Heavy Industry Co., Ltd., "Yuan ‘an" has achieved outstanding achievements since its initial excavation, with the highest daily excavation of 11 rings and 22 meters and the highest monthly excavation of 181 rings and 362 meters. As the first domestic super-large diameter slurry balance shield machine with atmospheric tool change, the application of atmospheric tool change technology has also achieved gratifying results. Up to now, in the construction operation, the equipment has been changed for 20 times, and 134 tools have been successfully changed. The tool changing operation is stable, efficient, safe and reliable, which indicates that the shield machine independently developed by China Railway Construction Heavy Industry is maturing in the research and development and application field of atmospheric tool changing technology.
It is understood that in the past, if the domestic slurry shield machine needed to replace the cutter, it was necessary to pressurize the pressure chamber behind the cutter head to ensure that it maintained a considerable pressure with the formation environment. The staff was "fully armed" to replace the cutter in a high-pressure environment twice higher than the normal air pressure, and the risk factor was high. Normal pressure tool changing technology effectively avoids the risk of tool changing under pressure by the staff of slurry shield machine, and greatly improves the efficiency of tool changing operation. According to the application situation, it only takes 40 minutes to change a knife under normal pressure, while it takes 1 day to change a knife under pressure.
At present, the construction of Yuanjiang tunnel in Changde is advancing the follow-up work safely and orderly, and it is expected that the whole project will be completed by the end of July.
[Editor: Wang Li]