Analysis of the Impact of Layered Expansive Surrounding Rock on Shield Tunnel Structures Considering the Effect of Expansion Softening
In order to explore the effect of swelling and softening on large-diameter shield tunnel structure of expansive layered stratum.This study used FLAC3D numerical software to establish a numerical model for the analysis of pipe segment expansion surrounding rock,and analyzed the expansion effect of layered expansion strata at different locations from the tunnel.Explored the stress changes and displacement response of tunnel structures under the influence of layered strata expansion.The conclusion is as follows:① When the upper layer of the tunnel undergoes expansion,the overall settlement of the pipe segment occurs.When the tunnel passes through the expansion layer and the expansion layer is located in the lower part of the tunnel,the pipe segment rises upwards as a whole.②After the formation expansion occurs,the structure undergoes relative movement with the surrounding strata due to the expansion effect,and the structure shifts towards the expansion area due to the softening effect of the expanded strata.③ When expansion occurs in the upper and lower parts of the tunnel,the stress in the segment structure decreases,and when the tunnel passes through the expansive formation,the stress in the segment significantly increases,reaching a maximum of 7.5 MPa.④ To reduce the impact of expansion on the tunnel,the strength of the surrounding rock at the bottom of the tunnel can be appropriately enhanced,while increasing the amount of synchronous grouting to reduce the expansion force on the pipe segments.
expansive rock and soilshield tunnelstructural stressexpansion softeninglayered strata
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