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| Deformation characteristics of surrounding rock and support stress in tunnels crossing fault fracture zones |
| WEI Jian1，CHANG Weixue2,3*，LIANG Qingguo2，QI Liangbin1，LI Qiwei2
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| (1.Gansu Shunda Road and Bridge Construction Co.,Ltd.，Lanzhou 730050, Gansu, China; 2. School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China; 3. Gansu Highway Traffic Construction Group Co., Ltd.，Lanzhou 730030, Gansu, China) |
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Abstract To address the problem of large deformation of surrounding rock in tunnels crossing fault fracture zones, the Heimaguan Tunnel was taken as the engineering background. Based on the field monitoring data of surrounding rock pressure, crown settlement, and horizontal convergence obtained from 23 monitoring sections, the deformation evolution characteristics of the surrounding rock and the mechanical behavior of the supporting structures were systematically analyzed.The results showed that significant deformation occurred in the fault fracture zone section. The maximum unilateral horizontal convergence reached 787.7 mm, while the maximum crown settlement reached 472.6 mm, exhibiting typical characteristics of large deformation in fault fracture zones. The deformation and pressure of the surrounding rock exhibited significant spatial discreteness, with the coefficients of variation of crown settlement and horizontal convergence reaching 83.2% and 93.0%, respectively, indicating the highly heterogeneous nature of the surrounding rock within the fault fracture zone. During the construction stage, the load-sharing ratio of the secondary lining ranged from 5.18% to 38.46%, with an average 20.29%, indicating that the surrounding rock load was mainly borne by the primary support, while approximately 20% of the load was carried by the secondary lining. Under the coupled effects of high in-situ stress, bedding-controlled structure, and groundwater softening, the surrounding rock deformation and support stress exhibited pronounced spatial non-uniformity. The research results can be referred to for the control of large deformation and the support design of similar tunnels crossing fault fracture zones.
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Received: 09 March 2026
Published: 26 May 2026
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