关键词: 盾构隧道, 近距离施工, 开挖面稳定, 颗粒流模拟, 土压力分布模式

Abstract: When several subway lines intersect, the excavation disturbance of the new shielded excavated tunnel in the crossing section is very complicated. When the existing tunnels are close to the new tunnel excavation, not only will the ground settlement be induced, but also will an adverse effect be made on the existing tunnels. For the construction form of the new shielded tunnel excavation under crossing the existing tunnel in active service, a 2D discrete element numerical model was established to study the failure surface of the shielded tunnel excavation passing through the existing tunnel nearby. In addition, the longitudinal ground deformation caused by the excavation and the distribution pattern of the soil pressure around the tunnel has also been analyzed. The results show that with the increase of the displacement of the excavation face, the support pressure of the shielded excavation increases first and then decreases. Due to the presence of the existing tunnel, the excavation face is gradually away from the existing tunnel, the pressure of the shielded excavation face is larger than that of the excavation approaching the existing tunnel. Further, the maximum ground surface settlement value is in the range of 2D from the center of the existing tunnel. With the advance of the shielded excavation, the earth pressure on the segment of the new tunnel appears to be a trend of gradual increase. When the tunnel is away from the existing tunnel, the lateral earth pressure on the top of the tunnel increases gradually, and the earth pressure along the depth direction in the front of the shielded excavation surface is significantly nonlinear.

Key words: Shielded Tunnel Excavation, Adjacent Construction, Excavation Face Stability, Particle Flow Code Simulation, Earth Pressure Distribution Model