Abstract:

Surcharge in shield tunnels can effectively restrain the uplift deformation of tunnels. In order to study the influence of surcharge on the longitudinal settlement and deformation of tunnel, the cooperative deformation model, comprehensively considering the rotation and dislocation effect of shield tunnel segment ring, is adopted. And then the tunnel additional load caused by surcharge is deduced and calculated. Meanwhile, the longitudinal settlement of the tunnel, the shear force, the amount of dislocation and rotation angle among the rings are derived based on the principle of minimum potential energy. Finally, the influences of different surcharge sizes, surcharge ranges and soil conditions on longitudinal settlement and displacement are studied. The results show that: (1) The calculated results by the method mentioned above are in good agreement with the measured and simulated ones, which proves the reliability of the method. (2) The additional stress and settlement of the tunnel caused by surcharge are normally distributed along the longitudinal direction; the maximum additional stress and settlement appear in the center of surcharge and are approximately proportional to the size of surcharge. (3) The variation rules of the shear force and the amount of dislocation and rotation angle among the rings are the same, which is approximately 0 in the center of the surcharge, but increases sharply on both sides of the center. (4) With the increase of surcharge range, the settlement of tunnel increases correspondingly, but the growth rate gradually slows down. (5) Different soil conditions have great influence on the settlement amount and settlement range of tunnel caused by surcharge.

Key words: shield tunnel, surcharge in tunnel, tunnel deformation, segment ring dislocation deformation, segment ring rotational deformation