Influences of Train Vibration on Integrated Assembled Internal Structures of Shield Tunnels Foundations on Cavities

The integrated prefabrication for internal structures of shield tunnels is of great significance to improve construction efficiency and guarantee construction quality. However, due to the difference in connection strength and quality of assembled components, the vibration response caused by the passage of trains on shield tunnel foundations on cavities will have negative effect on the force and deformation of the assembled internal structure. Against the background of Jintang Submarine Tunnel of Yongzhou Railway, two connection methods (fixed at both ends, fixed at one end and horizontally hinged at the other end) of integrated assembled internal structures with shield segments and partially assembled internal structures with unclosedly secondary linings were proposed, the influence of cavities in foundation under different internal structures on the cumulatively basal settlement and internal forces under vibration in operation of trains was studied. The research indicated that: 1) Cavities under foundations would increase the cumuletively basal settlement, but the cumulatively basal settlement of the integrated assembled internal structure fixed with shield segments at both ends was minimum, it showed that the strengthening of the connection between the internal structure and the segments could reduce cumulative deformation under reciprocating loads by trains; 2) Cavities under founndations would increase internal forces in shield segments and internal structures, and produce stress concentration in the lining in the corresponding area. Cavities would hinder transfer of vibration energy to segments, resulting in the sharp increase of shear amplitude in connecting bolts in the integrated assembled internal structure and the accumulation of vibration energy at the arch bottom, which would intensify the cumulative response of vibration.