Abstract:

The fiber Bragg grating (FBG) technology is widely used in tunnels with harsh environments because of its small size, simple structure, and strong antiinterference ability. In this study, the FBG technology is combined with the supporting bolt to propose an intelligent bolt monitoring method based on FBG, the testing principle and manufacturing process of the intelligent bolt are presented, and the relationship between the wavelength change of the measuring point of the intelligent bolt and the stress of the bolt is calibrated through indoor tests. The test results indicate a high linear fit. Furthermore, the FBG intelligent bolt is applied to the surrounding rock deformation monitoring of the Pingyang largecrosssection water conveyance tunnel, and the bolt support effect is evaluated in combination with the steel arch strain data obtained by FBG strain gauge. The monitoring results show that the intelligent bolt can achieve more accurate measurement of surrounding rock stress. During the construction of the drilling and blasting tunnel, the pressure on the bolt along the depth direction from the surface gradually decreases. Due to the supporting effect of the bolt, the stress strength of the steel arch is reduced.

Key words: largecrosssection water conveyance tunnel, fiber Bragg grating, intelligent anchor bolt, safety monitoring