The longest shield tunnel of line 22 was connected by two lines

Following the successful exit of the "tiebing no. 1" shield tunneling machine, "tiebing no. 2", the last shield tunneling machine in charge of the construction of metro line 22 from qi-fu to guangzhou south railway station (hereinafter referred to as "qi-guang section"), also completed the construction task successfully on May 18, marking the completion of the double-line tunnel in this area. This is the longest shield range on the whole line and the first to realize the connection between the two tunnels.

● "longest" tunnel construction to overcome multiple difficulties

The length of the tunnel is about 6,500 meters. The first branch of guangzhou metro line 22 of China railway construction south China co., LTD. (tube section of China railway 19th bureau) has invested four shield tunneling machines for tunnel construction. Among them, tiebing no. 2, which was launched on October 8, 2018, is responsible for the tunneling task of the left line tunnel between the qi-guang intermediate air shaft and qi-fu interval. The tunnel is 4,040.14 meters long, which is the longest tunnel on the whole line.

Shield tunneling, the subway builders in compound formation of shield construction into full play the management experience and technology accumulation, formulate the corresponding construction technology scheme and special contingency plans, from the aspect of management, technology and comprehensive coordination, and and local government, the village committee and so on has established the good emergency contact mechanism, implements 24 hours for shield construction machine monitoring, in order to ensure construction safety. During the construction, shield tunneling machine has successfully penetrated residential buildings, dapeng gas pipeline, high-speed tunnel and other major risk sources.

● innovative construction technology to resolve complex geological challenges

During the construction of "qiguang section", the shield tunneling machine successfully penetrated the river and the complex stratum successively. Among them, the silty sand content of the argillaceous siltstone formation in the right line tunnel is 50 ~ 70%, and the wear amount of cutter disc and cutter is large. To solve this problem, the subway builders on the basis of geology to customise, the knife dish article increase wear resistance and wear resistance network, cutting tools, screw machine barrel wall, selection of blade are made the wear-resisting performance is good material, at the same time using HengDun build pressure and mud on the ground outside pressure chamber configuration storehouse auxiliary work, open to ensure the construction safety.

In addition, in order to improve the construction efficiency, the subway builders also innovatively adopted the continuous belt system in the hole and the vertical belt system in the end shaft, which is also the first application of this system in guangzhou subway construction project. The system is composed of continuous belt, vertical lifting belt, belt storage bin and other large parts. During the construction, the supporting belt conveyor will transfer the dregs to the continuous belt conveyor after shield tunneling, and then to the composite belt conveyor. Finally, the dregs will be sent to the dregs pit and then transported out. By using this technology, the shield tunneling can be excavated continuously during the construction of shield tunneling, so that the assembling time of each ring of shield tunneling pipe slice is reduced from the original 2 hours to 1.3 hours, and the tunneling efficiency of shield tunneling is greatly improved.

In addition, due to the long distance between shield tunneling sections, in order to improve the measurement and control accuracy and ensure the accurate completion of the tunnel, the subway builders conducted repeated tests according to the construction schedule, and used the gyroscope to locate during the shield tunneling. The position change of the shield tunneling machine was induced, which effectively improved the accuracy of the construction survey.

Up to now, the civil engineering of line 22 has completed 43% in total. Among the 8 stations, 2 are covered by the main structure, 2 are for civil construction, and 4 are for pre-construction preparation. Among the seven sections, three carried out civil construction and four carried out pre-construction preparation. Chen tou gang parking lot for civil construction.