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Study on Support Characteristics of Super-large Section Tunnels in Unfavorable Geological Condition and Related Engineering Application
(1. Key Laboratory of Fujian Universities for Underground Engineering, Fujian University of Technology, Fuzhou 350118;2. Fujian Provincial Key Laboratory of Advanced Technology and Informatization in Civil Engineering, Fuzhou 350118;3. China Railway 24th Bureau Group Fujian Railway Construction Co. Ltd., Fuzhou 351111; 4. School of Civil & Architectural Engineering, East China University of Technology, Nanchang 330013)
Abstract Improper support for the construction of super-large section tunnels in weak and fractured ground is very likely to cause collapse and instability. Therefore, a thorough understanding of support characteristics and the selection of reasonable support parameters is the key to ensuring tunnel stability. In this study, based on the actual geological and environmental characteristics of a typical super-large section highway tunnel in Fujian province, four support schemes are designed. Through numerical simulation and on-site test, the mechanical characteristics of the surrounding rock, tunnel face and support structure under single advance support, double-layer advance support and only double-layer initial support are analyzed in depth, and the action mechanism of advance support is discussed, and furthermore a reasonable support scheme is proposed on this basis. The results show that under a single advance support (small pipes or pipe umbrella), the deformation of the surrounding rock can be reduced by 13% to 28%. Under double-layer advance support (pipe umbrella + small pipes or double layers of small pipes), the deformation of surrounding rock can be reduced by 51%~58%, and the stress state of the support can also be significantly improved. With the increasing strength of advance support, the deformation of surrounding rock significantly decreases, the reduction rate even exceeds 50% and a support effect of "1+1>2" is achieved, and the overall support effect of the pipe umbrella is slightly better than that of the small pipes. This conclusion is basically consistent with the on-site test result, verifying the rationality of the calculation method and the support plan. Based on the analysis results, a support plan for the tunnel section under-crossing the highway and other surrounding rock sections has been proposed. Practice has proven that the plan is feasible and has taken into account tunnel safety, economy of the support and rigidity matching
Abstract：
Improper support for the construction of super-large section tunnels in weak and fractured ground is very likely to cause collapse and instability. Therefore, a thorough understanding of support characteristics and the selection of reasonable support parameters is the key to ensuring tunnel stability. In this study, based on the actual geological and environmental characteristics of a typical super-large section highway tunnel in Fujian province, four support schemes are designed. Through numerical simulation and on-site test, the mechanical characteristics of the surrounding rock, tunnel face and support structure under single advance support, double-layer advance support and only double-layer initial support are analyzed in depth, and the action mechanism of advance support is discussed, and furthermore a reasonable support scheme is proposed on this basis. The results show that under a single advance support (small pipes or pipe umbrella), the deformation of the surrounding rock can be reduced by 13% to 28%. Under double-layer advance support (pipe umbrella + small pipes or double layers of small pipes), the deformation of surrounding rock can be reduced by 51%~58%, and the stress state of the support can also be significantly improved. With the increasing strength of advance support, the deformation of surrounding rock significantly decreases, the reduction rate even exceeds 50% and a support effect of "1+1>2" is achieved, and the overall support effect of the pipe umbrella is slightly better than that of the small pipes. This conclusion is basically consistent with the on-site test result, verifying the rationality of the calculation method and the support plan. Based on the analysis results, a support plan for the tunnel section under-crossing the highway and other surrounding rock sections has been proposed. Practice has proven that the plan is feasible and has taken into account tunnel safety, economy of the support and rigidity matching
YAO Zhixiong1,
2 ZHOU Qichuang1 ZHENG Guowen3 WU Bo4 FAN Lanxin1 QIN Haoyu1
.Study on Support Characteristics of Super-large Section Tunnels in Unfavorable Geological Condition and Related Engineering Application[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(5): 88-98
2023, Vol. 60 