Study on Reinforcement Technology of Secondary Lining Structure in Expressway Tunnel

The combination technique in this paper for reinforcement of one expressway tunnel with insufficient lining thickness and crack segment is a new method and material of grid steel strips. Its flat and disturbance to tunnel lining structure is slight. Its bending section modulus can be increased 45 times compared with common W-type steel strips. Its stiffness is increased 65 times and its tensile strength can be increased up to 11% ∼ 14%. This new type of grid steel strip is more suitable to deal with less stable surrounding rock support lining structures. The thickness of general W-type steel strip is less than 3mm, while this thickness of the new strip can reach 5mm. The method adopts the scheme when cracks occur in highway tunnel secondary lining structures and this new type of steel strips are usually utilized with carbon fiber and crack perfusion to preprocess crack to reinforce the external. Based on one of the expressway tunnels in northwest area of China for its lining concrete structure cracks, this article elaborates the main performance and characteristics of this new type of steel strip. A software is used to conduct a finite element analysis to crack section structure on the safety of tunnel lining thickness. This paper puts forward effective comparative analysis of its secondary lining structure reinforcement measures and better technical measures for application engineering lining structure reinforcement and leakage of underground water. It provides a useful reference and example for similar future engineering construction.