Double fiber bragg grating sensor for rock bolt anchoring quality test

Abstract

The invention discloses a double fiber bragg grating sensor for rock bolt anchoring quality test. The sensor comprises a clip for clamping an annular housing at the tip of the rock bolt; on one end of the inner wall of the clip is provided with an elastic block I along the axial direction of rock bolt, and the other end is provided with an elastic block II; a sensing optical grating is placed in the elastic block I; and a matching optical grating in a free state is placed in the elastic block II, and the sensing optical grating and matching optical grating have the same Bragg grating parameters. Two optical gratings at a preset interval are in a same fiber, the optical fiber passes through the clip and is connected with the data processing device. After excitation of elastic wave by the tip of the rock bolt, the elastic wave propagating along the rock bolt or reflected elastic wave acts on the sensing optical grating to cause the migration of reflection spectrum central wavelength of the sensing optical grating, and the overlapping region with the reflection spectrum of the matching grating is subjected to light intensity demodulation and data processing, so as to obtain time domain or frequency domain characteristics of the elastic wave signals.

Description

technical field [0001] The invention discloses a dual optical fiber grating sensor used for anchorage quality detection of anchor bolts. Background technique [0002] Anchor rods are widely used in highways, railways, mines, civil construction and other projects, mainly for slope reinforcement and underground support. In the bolt anchoring technology, the length of the anchor bolt embedded in the rock and the mortar saturation between the anchor bolt and the rock are the key to evaluating whether the bolt can exert its maximum effect. The main task of quality inspection. The traditional anchoring quality inspection methods are pull-out test method and coring method. Although this method is intuitive, it is a destructive inspection method and has great limitations. Several types of sensors, such as resistance strain gauge, differential resistance strain gauge, steel string and hydraulic pillow, have been developed subsequently. These electromechanical sensitive components h...

AI Technical Summary

Problems solved by technology

There are some research reports on sensors made of fiber grating devices. For example, Jiang Desheng and Nan Qiuming of Wuhan University of Technology used pasted fiber grating sensors to distribute and long-term detect the stress of prestressed anchor rods; developed by Chai Jing and Li Yi of Xi'an University of Science and Technology A fiber grating anchor dynamometer with temperature compensation is developed; these sensors are applied prestress to the anchor and then use the grating to detect the stress, which belongs to the measurement of static force, with high measurement accuracy and good linearity, but the structure is relatively complex and somewhat destructive

Images