Abstract Considering that segment joints have a great influence on the deformation and seismic response of shield tunnels, a real segment connection model with FLAC 3D software was established and the rotation angles of the joints as a function of the designed positive and negative moments were calculated along with axial forces considering three segment layout patterns using the Nanjing Weisan Road large-diameter river-crossing shield tunnel as an example. Based on a simplified continuous and heterogeneous ring model, the material stiffnesses at the weak parts of the segment joints were equivalently modified according to the rotation angles, and the seismic responses of the tunnel structures affected by the EI Centro wave were analyzed with respect to different segment layout patterns. The results show that: 1) the segment layout pattern may affect the tunnel dynamic characteristics within 1.2 s after an earthquake; 2) the time-history curve magnitudes of the horizontal acceleration at the crown and bottom decrease with a decrease of the angle of the key segment; 3) regarding the three segment layout patterns, the greatest tensile stress may occur in a range of 60° on each side of the crown and bottom after a seism; and 4) the distribution and magnitude of the maximum principle stress are affected by the joint area distribution pattern and the key segment dimension, respectively.
Abstract：
Considering that segment joints have a great influence on the deformation and seismic response of shield tunnels, a real segment connection model with FLAC 3D software was established and the rotation angles of the joints as a function of the designed positive and negative moments were calculated along with axial forces considering three segment layout patterns using the Nanjing Weisan Road large-diameter river-crossing shield tunnel as an example. Based on a simplified continuous and heterogeneous ring model, the material stiffnesses at the weak parts of the segment joints were equivalently modified according to the rotation angles, and the seismic responses of the tunnel structures affected by the EI Centro wave were analyzed with respect to different segment layout patterns. The results show that: 1) the segment layout pattern may affect the tunnel dynamic characteristics within 1.2 s after an earthquake; 2) the time-history curve magnitudes of the horizontal acceleration at the crown and bottom decrease with a decrease of the angle of the key segment; 3) regarding the three segment layout patterns, the greatest tensile stress may occur in a range of 60° on each side of the crown and bottom after a seism; and 4) the distribution and magnitude of the maximum principle stress are affected by the joint area distribution pattern and the key segment dimension, respectively.
2015, Vol. 52 