Measurement and Analysis of Structure Behavior of Cross-river Shield Tunnel with Large Diameter

Based on the Nanjing Metro Line 3 cross-river tunnel, the load and reinforcement stress of the 3 loop tubes was monitored by cross-river shield tunnel with large diameter, and the measured data were statistically analyzed. To explore cross-river shield tunnel during the construction and after construction for a period of time, load, the stress variation characteristics of shield tunnel, and internal forces of shield segments were calculated based on the field measured stresses. The uniform rigidity ring method and beam-spring method were used to calculate the internal force of tunnel lining, and compared with the measured value. The results show that the process of shield tunneling will cause the disturbance of the soil around the segment, the grouting behind the wall of the segment and the temporary load during the construction period will affect the distribution and value of the earth pressure around the segment. The change law of steel stress inside and outside the segment is basically consistent with the changing trend of measured earth pressure. The measured stress of the segment is shorter than the earth pressure to reach stable state. The internal force of the cross section of segment calculated by the beam-spring method is close to the measured result, and the back-calculation results are approximately twice as much as the axial forces of segments calculated. The results can provide reference for the design and construction of shield tunnel with similar condition.