Review on Tunnel Concrete Invert NDT Methods

Tunnel concrete invert is very important to the stability of the entire tunnel structure. However, invert’s quality is usually insufficient due to various reasons. Traditional approaches to detecting tunnel concrete invert focus on inefficient coring. The results of detection often cannot reflect all realities of the invert and concrete fill layer. These approaches are short of meeting current detection requirements for concrete invert. In order to increase the effectiveness and accuracy of invert test this paper summarizes technical features of GPR method and Rayleigh wave method according to concrete structure NDT and tunnel invert test technologies at home and abroad. The results show: the GPR method is simple and efficient and capable of qualitative test of tunnel invert, though with a trade-off between detection depth and accuracy; the Rayleigh wave method provides high accuracy and the qualitative test ability for tunnel invert thickness and unconsolidated fill, though inefficient due to a lack of pertinent equipment.