Recently, the west extension of Line 4 and the first phase of Line 24, which were constructed by Chongqing Rail Group and undertaken by China Power Construction and China Railway Construction respectively, successfully completed the tunnel node project, seizing the golden period of construction and steadily advancing the construction progress.
Line 4 West Extension
On April 16, with the "New Journey No. 3" TBM huge cutterhead breaking through the wall, the left line tunnel of the TBM section of Huayuan Station ~ Longxi Station (hereinafter referred to as the "Hualong section") was successfully completed, which marked the breakthrough of the two-way tunnel in the Hualong section and laid a solid foundation for entering a new construction stage.
The Hualong section is 610.5 meters long, and the line passes through key buildings (structures) such as residential areas, urban interchanges, and commercial buildings. The section is a single-hole single-lane tunnel, with a minimum turning radius of 450 meters and a buried depth of 33.8~42.5 meters at the tunnel vault. The TBM "New Journey No. 3" in this excavation construction is a composite EPB shield machine equipped by China Railway, with a total length of about 97 meters and a weight of 450 tons. The segmental lining ring has an inner diameter of 5900 mm, an outer diameter of 6600 mm, a thickness of 350 mm and a width of 1500 mm.
In order to ensure the safety and progress of construction, the rail group and the construction unit, with the goal of construction safety quality control, have successively optimized the TBM excavation attitude control and construction process risk control, overcome the problem of difficulty in slag removal caused by lateral starting, and through BIM technology dynamic simulation, visual disclosure and other information means, safely and efficiently solve the shield translation and rotation in a narrow space, ensure the safe and rapid launch and excavation of TBM, and effectively improve the construction efficiency.
After more than 100 days of full advancement, "New Journey No. 3" successfully excavated with the construction method of "slag removal in the station", and finally received it at the small mileage end of Longxi Station, and successfully completed the task of tunneling the left line of the Hualong section.
At present, a total of 8.1 kilometers of TBM section of the western extension of Line 4 has been completed, and in addition to the Hualong section, there are three sections of Longxi Station ~ Jiazhou Road Station, Jiazhou Road Station ~ Min'an Avenue section, Yupan section Launch Well ~ Panxi Station section have achieved tunnel penetration.
The west extension of Line 4 starts from Pangui Road Station in the west to Min'an Avenue Station (built) in the east, and will be operated through the first and second phases of Line 4 after completion, connecting important areas such as Dashiba Group, Guanyinqiao Group, North Railway Station, Tangjiatuo Group, Longxing Group, etc., to further encrypt the rail transit network in the central urban area and facilitate the travel of citizens.
Phase I of Line 24
On April 16, with the completion of the excavation of the last section of the rock mass of Section A of Dilongwan Station ~ Waziba Station, it marked the breakthrough of the right line of the Dilongwan ~ Waziba Station section (hereinafter referred to as the "Diwa section") with a total length of 239.4 meters.
The "Pioneer No. 3" composite TBM undertook the excavation task of the tile section and successfully started at Waziba Station on February 29. "Pioneer No. 3" cutterhead with a diameter of 6.88 meters, a weight of 480 tons, and a total length of 73.62 meters, is planned to start from the right line of Waziba Station, and after realizing the task of breaking through the right line, the tunnel will be dismantled and turned in the tile section, and then the second time it will be sent to the receiving end of the left line of Waziba Station to complete the two-way tunnel boring task in the section.
In order to ensure the safety of construction, the joint construction unit of the rail group not only held an expert demonstration meeting before construction to ensure the high-quality completion of the key processes such as hoisting, installation, commissioning, and acceptance of the starting conditions of the shield machine, but also strengthened the research and demonstration of the construction plan, and used the sleeve valve pipe construction technology for grouting reinforcement to solve the geological problems of the backfill section of the tile section with high quality. Before construction, the construction unit also improved the cutterhead, increased the cutterhead opening rate, and equipped with an efficient and reliable muck improvement system and blowout prevention device, which greatly improved the adaptability of TBM, reduced the disturbance to the surrounding soil layer, and ensured the operation efficiency of the shield machine.
In the next stage, the rail group and the construction unit will actively overcome the construction difficulties such as the cast-in-situ construction of the bracket and the secondary lining of the large section to ensure the smooth progress of the follow-up construction tasks.
The first phase of Metro Line 24 starts from Banan District and ends at Guangyangwan Station in Nan'an District, with a total length of 18.82 kilometers, which is interchangeable with the east extension of Line 6, Line 8 and Line 27 respectively. The line is one of the backbone lines in Chongqing's rail transit construction network, and it is also the first rail transit line in Chongqing that is fully autonomous and adopts a cloud-based Internet of Things convergence platform. After completion, it can effectively improve the north-south transportation capacity of rail transit, enhance the radiation range of Chongqing East Railway Station, support the regional development of Guangyang Island, meet the development needs of the eastern trough valley, provide convenience for citizens to travel, and provide pioneer conditions for future industrial clusters.
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Text: Huang Linshui, Peng Changhai, Yi Ziying
Photo courtesy of Project 2 & 3 companies
Editor: Fan Run
校对：刘 畅责编：苏 阳终审：胡潆兮
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