Hazards of Waterproof Board Cutting Secondary Lining in Operating Tunnel and Remediation Schemes

Objective With the acceleration of tunnel construction in China, various diseases in operating tunnels become increasingly prominent. Despite of many in-depth researches by scholars on various diseases, that on the hazards of waterproof board cutting secondary lining is still insufficient. Therefore, it is necessary to deeply explore the secondary lining cutting hazard in operating tunnels and propose effective remediation schemes. Method Based on the waterproofing and force mechanism of waterproof boards, numerical simulation technology is used to systematically study the secondary lining cutting hazard in operating tunnels. Focusing on the waterproof board arch bending moment, the Mises stress and the lining displacement under different circumferential and longitudinal cutting lengths, the changing law of their key indicators are emphatically analyzed. On this basis, a new remediation design scheme is proposed, and the rationality-superiority of the remediation design scheme is verified by comparing the changes in the lining structure vault displacement before and after the waterproof board remediation. Result & Conclusion With the increase in the circumferential and longitudinal cutting lengths of the waterproof board, the arch bending moment, the lining stress and displacement all show a significant growth trend. In particular, the longitudinal cutting length of the waterproof board has a more significant impact on the three indicators such as lining displacement. Through comprehensively analyzing the sudden change areas of bending moment, stress and displacement, it is found that when the waterproof board circumferential and longitudinal cutting lengths are in the range of 2~3 m, the impact on stress and deformation of the lining structure is most unfavorable.