Chengshi guidao jiaotong yanjiu (Jul 2024)
Impact Analysis of Connecting Passage Shield Method Construction on Interval Shield Tunnel in High-confined Aquifer Soft Soil Area
Abstract
Objective During the construction of shield method connecting passage, the jacking and cutting actions cause significant changes in the stress at tunnel intersection, exacerbating the impact of breakthroughs and reducing safety performance. To efficiently achieve construction control, it is necessary to conduct an in-depth study of the stress characteristics of the main tunnel structure. Method Based on the first shield method connecting passage project in Tianjin Metro, by using finite element software to simulate the construction process of the mentioned connecting passage, the impact of this construction method on the stress and deformation of the main tunnel structure is analyzed, and corresponding control measures are proposed. Result & Conclusion At the launching stage of the connecting passage, due to the jacking and cutting actions on the originating tunnel, segments near the portal experience significant deformation and stress changes, with the maximum horizontal displacement occurring at segments on arch waist opposite to portal. During the receiving stage, the receiving tunnel is affected by cutting actions and soil excavation unloading, resulting in significant segment internal force changes l and deformation towards the connecting passage. Overall, the affected area mainly centers approximately in 10 m periphery on both sides of the connecting passage axis, about 3 times the diameter of the connecting passage. Based on this, attention should be given to the segments near the jacking and portal areas. To ensure construction safety, it is recommended to optimize the internal support system by reducing the support range of the gantry shoe to twice the connecting passage diameter, and cut off the construction cost by reducing the thickness of the gantry steel plate or the thickness of the support steel pipe wall.
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