Study On Key Technologies Of The Metro Station Constructed By Shield Tunneling Method Combined With Mining Method

Expanding metro station under shield running tunnel, can solve the contradiction of construction time between shield tunnel sections and adjoining stations, improve the efficiency of shield machine, reduce the project cost, fully play the advantages of shield tunneling on speed, long distance, and quality, thereby it will enhance the speed of the construction work in the whole line and optimize the whole project planning.Based on the preliminary research on schemes of constructing metro station by shield tunneling method combined with mining method, the construction scheme and key technologies were further studied in this paper by the research methods including numerical simulation, joint model test, and theoretical analysis. The main work and the achievement are as follows:(1) For the different construction time of secondary lining in station tunnel in the construction process of metro station by shield tunneling method combined with mining method, two kinds of construction schemes were put forwarded. The two construction schemes were simulated by three-dimension numerical method, and the internal force of the tunnel structure and the surface displacement were compared and analyzed. The results indicate that secondary lining in station tunnel must be constructed before excavating cross aisles.(2) Shield lining segments were simulated by the shell-spring-contact model, which can consider the hoop connection between segments and the longitudinal connection between segment rings. The stability of shield lining segments in the construction process were deeply researched by the aspects of the force and deformation of segments, the force of hoop bolts between segments and longitudinal bolts between segment rings, and the deformation of segment joints. The results indicate that the conventional designed segments meet the requirements in the construction process, only the force of part of ring bolts between segments and lengthways bolts between segment rings exceed the required carrying capacity, so the strength grade of the bolts at these locations should be improved.(3) The joints between segments and main structure of the station were studied by the 1:1 scale joint model test. The force, deformation, and damage patterns of the joints were studied, and the security and stability of joints were evaluated quantificationally. The results indicate that the joints are safe considered the force. The joint connection method of embedding steel connecting device in the segments should be used to connect segments and main structure of the station.