On May 6, at 27 meters underground of the T3 terminal building of the Changsha Airport Reconstruction and Expansion Project, as the "Maglev No. 2" domestic shield machine was successfully dismantled and hoisted out, the east extension of Changsha Maglev was connected to the T3 terminal The civil engineering of the section between Maglev T2 Station and Maglev T3 Station has been completed, and the Changsha Maglev East Extension Line connected to T3 Terminal is located in Huanghua Town, Changsha County. It is laid to T3 Terminal with a curve radius of 300-350 meters. The total length of the line is 4.454 Km, is the completion of the point-to-point fast connection between Changsha South Railway Station and Huanghua Airport T3 Terminal, marking the first medium-low speed maglev in China constructed by the Changsha Rail Maglev Line Construction Company and undertaken by the China Railway 14th Bureau. The tunnel runs through.

■ Underpass the sensitive area of the airport, and the shield underground makes a "sharp turn"

The east extension of Changsha Maglev passes through the sensitive area of Changsha Huanghua International Airport. It is the first shield tunneling construction in the area of Huanghua International Airport. The subsidence control and safety risk requirements are high, and the underground construction is difficult. In addition, the shield machine is on a right-turning curve with a radius of 300 meters at the start, and the start is a sharp turn. It must be started on a secant line, and the difficulty is doubled compared with the normal straight line start.

Project leader Yang Linghang introduced, "The shield machine has passed through the airport aviation fuel pipeline 6 times, and has passed through the sensitive area of the airport runway slippery slope for a long distance, and crossed the upper soft and lower hard strata and other risk sources. The construction settlement control is directly related to the aircraft takeoff. Safety. During the excavation process of the shield machine, there are many curves with small radii and large deflection angles, and the 83-meter-long shield machine has to make multiple 'sharp turns' underground."

■ The combination of maglev and shield for the first time, and the precision control is extremely strict

This project is the first time that the shield method is applied to the maglev project. The special mode of maglev transportation puts forward higher requirements for the tunnel construction.

In order to ensure a stable and controllable excavation process, China Railway 14th Bureau specially built two earth pressure balance shield machines according to the hydrogeological conditions in the airport and the surrounding environment. It is the shield machine with the largest diameter in the Changsha rail transit construction project so far. The composite cutter head with a rate of 38% optimizes the slag soil improvement system, improves the slag discharge efficiency, and reduces the disturbance of the surrounding strata to ensure the construction progress.

Aiming at the problem of small radius and large deflection angle curve excavation, a series of advanced construction methods are adopted to precisely control the posture of the shield. Deploy an intelligent monitoring system in advance to closely monitor when passing through sensitive areas of the airport, analyze, predict and feed back information in a timely manner to guide the tunneling of shield machines. Yang Linghang introduced, "Through all-weather monitoring, the settlement value of the sensitive area of the airport is only 0.2 mm, and the 'zero settlement' has been achieved."

As the world's first maglev tunnel constructed by the shield method, this project has established a new module combining shield tunneling and maglev, with high technological content and far-reaching influence in the industry.

■ The 7th anniversary of the operation of the maglev express line, the future of the east extension project can be expected

Back in time to May 6, 2016, the Changsha Maglev Express Line built by China Railway Construction Group Co., Ltd. began its trial operation. As of May 6 this year, the line has been in safe trial operation for the seventh anniversary.

As my country's first medium and low-speed maglev commercial operation demonstration project with complete independent intellectual property rights, the Changsha Maglev Express is a project that China Railway Construction adopts "investment and financing + design and construction general contracting + procurement + R&D + manufacturing + joint commissioning and testing + follow-up comprehensive development "A project constructed in an original mode, connecting Changsha South Railway Station and Changsha Huanghua Airport, with a total length of 18.55 kilometers.

Subsequently, the Changsha Maglev East Extension Project will enter the stage of track laying and electromechanical installation in an all-round way. After it is completed and put into operation in the future, it will be directly connected to the T2 and T3 terminals of Changsha Huanghua International Airport, which will greatly meet the airport's future collection and distribution needs. It is of great significance to build a comprehensive transportation hub centered on the airport. Editor / Xie Li