Influence of Construction Process of Double-Line Shield Tunnel Crossing Frame Structure on Ground Settlement

Abstract

This paper simulates the construction process of double-line shield tunnels crossing frame structure by using the three-dimensional finite element software MIDAS/GTS. The location and construction sequence of double-line shield tunnels were varied to investigate the influence on the ground settlement. The results show: (1) The transverse deformation curve of the ground caused by the construction of the double-line shield tunnel is symmetrical about the centerline of the tunnel. The existence of the frame structure affects ground settlement. It reflects the constraining effect of the frame structure on the formation. When the shield tunnel is excavated near the center of the frame structure, the frame structure has the greatest influence on the ground settlement. (2) The ground settlement of the center point of the strip foundation is selected as the research object. With the continuous excavation of the shield tunnel, the ground settlement curve has a slight increase. The curve drops when the shield is excavated to the frame structure. The curve levels off when the shield is excavated beyond the frame structure. It is no longer decreasing. (3) The difference in the relative position of the frame structure and the shield tunnel has a certain influence on the ground settlement. When the tunnel under-passing the frame structure, the ground settlement is minimal. (4) When the double-line shield tunnel crossing the frame structure from the side, the ground settlement caused by the reverse synchronous excavation process of the left and right lines is minimal at the center of the frame structure.