Nanjing Metro Line 4 Phase II Crossing Tunnel through the main channel section of the Yangtze River, the tunnel is 3062 meters long."The shield machine across the river is assembled and debugged from the middle wind shaft of Jiangxinzhou, and then excavated to the north and south of the river respectively." China Railway 14 Bureau project technology responsible person Shan Xiaobo said, which to the north of the river is the excavation diameter of 11.64 meters level of "new journey" mud-water balance shield machine.
In January this year, a mud-water balanced shield machine named "New Journey" was successfully launched in Changsha, and then transported to the middle wind shaft of Jiangxinzhou of Nanjing Metro Line 4 Phase 2, and started to assemble in the shaft in April.
The shield assembly is now complete.Everyone on the project is doing their best to carry out the final inspection and debugging of the shield machine, and the mud-water separation equipment and double liquid slurry mixing station on the ground are also under synchronized debugging, so as to make the final sprint for the shield machine to start.
It is understood that the work of the mud-water balanced shield machine is mainly to promote the excavation and pipe piece assembly of two parts. In the front of the shield machine on the cutter, there is an in and out of two channels, excavation process, the excavation surface will be prepared in advance of the mud through the pressure injected into the soil to be dug, the formation of mud film; in the formation of the mud film at the same time, the cutter is constantly rotating excavation of the soil, and will be excavated and cut down the soil and mud mixing to form a high-concentration slurry, the mud by the mud pipeline transported out of the shield machine, into the ground of the mud-water separation system for processing. The mud is transported out of the shield machine through the mud discharge pipe and into the mud-water separation system on the ground for treatment.
The shield machine stops every 2 meters it digs forward to assemble the prefabricated pipe pieces, and the entire tunnel is formed by connecting the prefabricated pipe pieces together in a ring.
As the most critical construction section of Line 4 Phase 2, the "New Journey" mud-water balanced shield machine will complete the most technically difficult part of the line.The shield structure construction crosses the powdery clay, powdery fine sand, medium-coarse sand, rounded gravel and other strata of the Yangtze River Mangtan, and the biggest test is the need to cross the middle-weathered muddy sandstone strata of about 700 meters long.
This domestic mud-water balanced shield machine has a total weight of 2,100 tons and a total length of 120 meters.The "synchronized injection of two-liquid slurry technology" is the first time to be applied in the construction of domestic subway tunnels across the river, and it is the first time to be applied in the construction of subway tunnels across the river.The efficiency and safety of the shield can be significantly improved.
It is reported that the shield machine in the Jiangxinzhou start, the top soil thickness of about 26.8 meters thick, across the Yangtze River, the deepest depth of soil thickness of about 55 meters, the receiving end of the soil thickness of 34 meters, for the Yangtze River Delta region's deepest cross-stream subway line.
First of all, the construction of corresponding supporting facilities sites on the ground should be completed, such as material warehouse, machining workshop, double liquid slurry mixing station, air compressor room, cooling tower, storage site for prefabricated parts of pipe sheet box culvert, mud-water separation system, etc. Underground, the assembly and commissioning of shield machine should be completed.
Secondly, in view of the situation of the river crossing tunnel, it is necessary to formulate a special construction plan in advance, carry out strict safety education and technical briefing for the construction workers, analyze the possible risks of the shield machine launching in advance, and do a good job of risk pre-control and the corresponding emergency plan. In addition, it is also necessary to carry out the burial of ground monitoring points, prefabrication of pipe sheets and box culverts.
"Only by doing a solid job on the front end.
It is only then that a solid foundation can be laid for subsequent construction."
Looking forward to the "New Journey" shield machine
early departure
Looking forward to Line 4 Phase 2
Early commissioning
