Research purposes:For construction of No 3 line’s shield tunnel under-passing the existed No 1 line’s tunnel of Shanghai metro, the mechanical behaviors of new tunnel construction were simulated with the three-dimensional fast Lagrangian analysis of continua (FLAC3D) method, the change and influencing scope of stratum stresses and the stresses and safety of structure were discussed, and the measures for and proposals to ensuring the construction safety of new tunnel and operation safety of existing tunnel were offered.
Research conclusions:The additional stresses distribution of existing tunnel was of laterally symmetrical status which took the central line of new tunnel as symmetry axis in construction process. The subsidence of the existing tunnel occurred and additional stresses of existing tunnel increased during construction of new tunnel. As the maximum internal force in the target face of the tunnel tubular lining appeared on the tubular lining on the arch web on both sides of new tunnel, the stratum between tunnels should be reinforced. When construction was finished, the main stress in the target face of the tubular lining of the shield tunnel became the biggest.