The soft soil layer in Shanghai has a high void ratio, compressibility, water content, and sensitivity, but low shear strength. Disturbance significantly reduces its strength, leading to prolonged consolidation and secondary consolidation settlement over several years. The tunnel structure laid in this kind of layer is affected by construction quality, storage conditions, dynamic and static loads during operation, and maintenance quality. As the service life increases, long-term issues such as overall settlement, differential settlement, and convergence deformation of the tunnel cross-section can lead to tunnel diseases worsening, such as structural damage, deformation, and water leakage. Meanwhile, construction activities around the tunnel intensify the development of structural defects, with these issues interacting and exacerbating each other. If left unmanaged and allowed to progress, they will inevitably threaten operational safety.