Diseases failures characteristics and countermeasures of expressway tunnel of water-rich strata: A case study

Various diseases failures inevitably appear in expressway tunnels in water-rich strata under the long-term erosion of water. In order to ensure the operation safety of Jizhao tunnel which is in Guizhou Province, China, the radar scanning, drilling and coring and laser scanning were employed to illuminate the diseases failures characteristics and the causes of the tunnel failures. Further, a complete set of solutions against cracks, water seepage and inverted uplift and other diseases was put forward innovatively and applied in the actual project. This case study seeks to examine the characteristics and causes of tunnel failure in water-rich strata. The results show that the water-rich strata, expansive soil and the development of surrounding rock joints are the main factors causing the failure of Jizhao tunnel. The cracking and damage of tunnel lining is dense and disorderly, the water leakage of lining is small but long-term, and only some sections have floor heave. The treatment of crack grouting, clay steel belt and low prestressed anchor bolt were adopted to ensure the integrity of secondary lining and rock mass. The method of adding inverted arch, foot locking bolt and bolt grouting taken in this tunnel is to improve the stability of the tunnel structure and alleviate the stress release in the later stage. Transverse drainage pipes and longitudinal drainage pipes were set to ensure smooth drainage. After the treatment scheme is adopted, the disease is effectively controlled and does not affect the normal operation of the tunnel, which can provide a certain reference for the failure treatment of similar tunnels projects.