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Analysis Method for Deformation of Existing Tunnel Induced by Tunnel
Anchor Excavation and Support
(1. Survey and Design Company of Sichuan Road & Bridge (Group) Co., Ltd., Chengdu 610041;
2. School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031)
Abstract In order to assess how tunnel anchor excavation and support will impact the safety of the existing tunnel
below, the calculation model for deformation of existing tunnel induced by tunnel anchor excavation and support has been created for the first time by using the theory of beam on elastic foundation, the method for calculating the additional load under the effect of tunnel anchor excavation and support has been devised based on the Mindlin formula,and it is established that the control standard for deformation safety of existing tunnel is 12 mm. By taking the Ningqiao Tunnel-tunnel anchor system of the Yanjiang Expressway in Sichuan as an example, the deformation characteristics of existing tunnel under the effect of tunnel anchor excavation and support have been analyzed. According to the study, the existing tunnel has convex shaped deformation, the maximum deformation happens right below the anchor plug, and the tunnel deformation gradually decreases as the distance of anchor plug increases until the convergence point. The deformation of existing tunnel increases as the surrounding rock grade decreases and the distance between tunnel and tunnel anchor decreases. With Classes Ⅲ and Ⅳ surrounding rocks, the tunnel is generally in safe state.With Class Ⅴ surrounding rock, the tunnel deformation exceeds the control value during tunnel anchor excavation,
so certain engineering measures are required, such as surrounding rock reinforcement and structure strengthening.
Abstract：
In order to assess how tunnel anchor excavation and support will impact the safety of the existing tunnel
below, the calculation model for deformation of existing tunnel induced by tunnel anchor excavation and support has been created for the first time by using the theory of beam on elastic foundation, the method for calculating the additional load under the effect of tunnel anchor excavation and support has been devised based on the Mindlin formula,and it is established that the control standard for deformation safety of existing tunnel is 12 mm. By taking the Ningqiao Tunnel-tunnel anchor system of the Yanjiang Expressway in Sichuan as an example, the deformation characteristics of existing tunnel under the effect of tunnel anchor excavation and support have been analyzed. According to the study, the existing tunnel has convex shaped deformation, the maximum deformation happens right below the anchor plug, and the tunnel deformation gradually decreases as the distance of anchor plug increases until the convergence point. The deformation of existing tunnel increases as the surrounding rock grade decreases and the distance between tunnel and tunnel anchor decreases. With Classes Ⅲ and Ⅳ surrounding rocks, the tunnel is generally in safe state.With Class Ⅴ surrounding rock, the tunnel deformation exceeds the control value during tunnel anchor excavation,
so certain engineering measures are required, such as surrounding rock reinforcement and structure strengthening.
ZHOU Jie1 XI Jinzhou1 LI Haiqing1 YU Li2 TANG Langzhou2
.Analysis Method for Deformation of Existing Tunnel Induced by Tunnel
Anchor Excavation and Support[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(6): 120-129
2023, Vol. 60 