Deformation characteristics of existing three-line tunnels with connected aisle induced by three-line mechanized tunnels under-crossing

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Publication Title
Deformation characteristics of existing three-line tunnels with connected aisle induced by three-line mechanized tunnels under-crossing

Abstract
Deformation characteristics of exiting tunnel induced by tunnel under-crossing is crucial for the safety of existing tunnel. A combination of manual low-frequency monitoring and wireless sensing high-frequency monitoring was used for an under-crossing case. The case is existing three-line tunnels under-crossed by new three-line mechanized tunnels and there is a connected aisle between two existing tunnels. The monitoring measured settlement and deformation of existing tunnels. Settlement monitoring results show that the settlement of existing tunnel during under-crossing experienced 2 stages: (i) heave, (ii) subsidence. The settlement profiles of the existing tunnels induced by the second tunnel under-crossing were found to be asymmetric with respect to the second tunnel line and the location of maximum settlement point deviated toward the center of the first under-crossing tunnel and the second under-crossing tunnel. For the third tunnel under-crossing, the situation is similar but the offset is not as much. Besides, the connected aisle also caused a longitudinal asymmetric distribution of deformation. Rotational deformation monitoring results show that the deformation of existing tunnel is more complex. When the cutter of tunnel boring machine (TBM) is right below the existing tunnel, the existing tunnel heaved during TBM advancing and subsided during TBM halting. When the shield tail is 0.4D in front and behind the existing tunnel in horizontal direction where D is the diameter of TBM, the existing tunnel heaved at most of time while subsided if the grouting volume is insufficient.
Authors
J. Q. Chang; D. M. Zhang; H. W. Huang; M. Thewes

Published In

18th European Conference on Soil Mechanics and Geotechnical Engineering (ECSMGE2024)

Theme

D - Current and new construction methods

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