An analysis of interaction of deep buried close approaching multi-line parallel shield tunneling

Construction of a second shield tunnel in shallow soft strata may reduce the safety of the first shield tunnel, especially when the clear spacing is very small. However, in the case of deep burial, the deformation of the first tunnel becomes complicated due to the complexity and uncertainty of the underground soil layer. With the shield tunnel of hard X-ray civil construction in Shanghai as the background, combined with finite element numerical simulation, the mutual influence during the construction of the deep-buried shield tunnels with small clear spacing is analyzed, and the sensitivity analysis of different shield parameters is carried out. The research results show that with the excavation of the later tunnel, the deformation increment of the first tunnel segment is basically bimodal. When the left-right- middle method is used, the deformation increment of the segment is of a big and a small bimodal distribution. In the middle-right-left method, the peak value of the vertical deformation increment is the same in size and direction, while the horizontal is the same in different directions. With the increase in the elastic modulus of grouting, the vertical deformation increment of the segment changes greatly, while the horizontal deformation increment is basically unchanged. When the pushing force increases, the deformation of the segment increases, and it reaches a stability when the supporting stress ratio is between 0.6-0.7. The existence of groundwater has a certain effect on the vertical deformation of the segment. By comparing the deformation convergence of the two excavation methods, the left-right-middle sequence of excavation is finally selected.