Mechanism Of Tunnel Lining Misfracture Under The Action Of Fracture Creep And Anti-fracture Measures

Along a certain railway line,there is a high concentration of active faults,with more than 50 large-scale faults,including over 10 regional active faults.The complex geological conditions,extensive fault zone scale,and significant displacement and creep characteristics of these active faults pose severe challenges to the safety of tunnel linings and axial stability during operation.This situation poses a serious threat to the safe operation of high-speed railways and remains a pressing issue that needs to be addressed in the construction process of railway tunnel projects.Therefore,studying the tunnel dislocation mechanism under fault creep and proposing corresponding fault-resistant measures is of great theoretical significance and engineering value.To reveal the mechanism of tunnel damage under creep fault movement,this paper focuses on a specific tunnel along the railway line.The research investigates the mechanisms of tunnel damage and fault-resistant measures under creep fault movement through theoretical analysis,geological mechanical model tests,and numerical simulation analysis.The combined approach of theoretical analysis and model tests is employed to study the mechanism and characteristics of tunnel damage under creep fault movement,while numerical simulation is utilized to investigate fault-resistant measures for tunnels.The main research contents are as follows:(1)Based on the Pasternak model of elastic foundation beam theory,the analytical expression for the longitudinal mechanical response of tunnel linings under active fault zone dislocation is derived,and the longitudinal deflection equation of the tunnel under fault zone dislocation is solved.By comparing and analyzing the analytical solution and numerical simulation results,the correctness of the theoretical model is validated.Theoretical analysis is conducted to investigate the dislocation response of tunnels crossing creeping fault zones based on the longitudinal distribution of fault zone displacement and different fault parameters and tunnel depth conditions.(2)Based on a tunnel engineering project,a similar material for tunnel surrounding rock is prepared according to the principles of material similarity,and parameter sensitivity analysis is performed on the preparation of similar materials.Using a self-developed model test system for studying the mechanism of tunnel lining damage when crossing active fault zones at deep burial depths,model tests with scaled ratios are conducted to simulate the damage process of tunnel linings after fault dislocation.The strain of tunnel linings and the stress variation of surrounding rock under different dislocation distances after fault dislocation are studied,revealing the mechanism and characteristics of tunnel damage caused by fault dislocation.(3)Numerical simulation software is utilized to study fault-resistant measures for tunnels crossing creeping fault zones.The fault-resistant measures include flexible hinge joints,energy dissipation buffers,and tunnel cross-section selection methods.By analyzing and comparing the effects of different parameters on the fault-resistant performance of tunnel linings,the effectiveness of the fault-resistant measures is verified.Combined with the geological conditions of a specific tunnel project,the fault-resistant measures are comprehensively applied to provide effective solutions for tunnel crossing the Yunnongxi active fault zone.The effectiveness of the combination structure of fault-resistant measures is validated through multiple perspectives.