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| Analytical solution for longitudinal response of tunnels with consideration of surrounding rock-concrete tangential interaction |
| CHANG Mingyu1，2，SHEN Yusheng1，2，ZHANG Xi1，2，WU Qingzi1，2，WANG Yanyan1，2，HUANG Haifeng1，2 |
| (1. Key Laboratory of Transportation Tunnel Engineering of Ministry of Education，Southwest Jiaotong University，Chengdu，Sichuan 610031，China；2. National Engineering Research Center of Geological Disaster Prevention Technology in Land Transportation，Southwest Jiaotong University，Chengdu，Sichuan 610031，China) |
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Abstract The existence of faults in high-intensity earthquake areas has a serious impact on engineering structures and the longitudinal response of tunnel crossing faults needs to be studied further. An analytical solution for longitudinal response of tunnels crossing faults is presented. For the derivation，the tangential foundation springs are used to analyze the tangential contact effect of surrounding rock-lining and axial deformation characteristics of tunnel. Firstly，the elastic foundation beam model is used to simulate the surrounding rock-tunnel structure interaction. Wherein，the displacement of free field is applied on the distal end of normal foundation spring and the tangential interaction is transformed into tangential foundation springs. The analytical solution of the tunnel?s response is gotten based on the model by using Green?s function. Secondly，the numerical solution from finite difference model of 3D is used to verify the validity of the proposed analytical solutions. The results show that the tangential contact effect of surrounding rock-lining has a significant impact on the longitudinal response of tunnel. Ignoring it，the peak bending moment error of structure reaches 35.33%. Finally，the effects of fault zone width，fault elastic modulus and lining concrete grade on the longitudinal response of tunnel are explored. As the fault zone width increases，the internal force of the tunnel structure decreases；increasing the lining concrete grade results in unfavorable effect on the structure；the increase in the elastic modulus of the surrounding rock in fault zone reduces the bending moment and shear force of structure，and increases the axial force，respectively. The research results can provide a theoretical basis for the anti-offset design of tunnels crossing faults.
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