Influence of Different Opening Positions of Shield Method Connecting Passage on Main Tunnel Segment Internal Force

Abstract

Objective In the 9 m level large-diameter shield tunneling, there are no engineering cases using shield method for constructing connecting passages yet. Due to the influence of clearance and evacuation platform height, a certain eccentricity exists between the connecting passage and the main tunnel, resulting in the impact of shield launching and receiving with eccentricity for main tunnel structure. It is necessary to investigate the influence of different opening positions of shield method connecting passage on the internal forces of main tunnel segments. Method Based on a city railway project, numerical simulation method is used to analyze the mechanical response of main tunnel segments during the launching and receiving stages of above connecting passage construction under different eccentricity conditions. Result & Conclusion During the construction of shield method connecting passages, the most critical stage is when the thrust acting on the shield reaction frame is zero. As the eccentricity increases, the convergence deformation of special segments in main tunnel and the internal forces in steel and concrete segments gradually decrease, while the circumferential and longitudinal shear forces gradually increase. The internal forces in ordinary concrete segments adjacent to the special segments on the opening side also increase significantly, which requires special attention in structure design.

Keywords

• city railway
• connecting passage
• shield method construction
• segment
• eccentricity
• internal force analysis