Crack monitoring sensor and use method thereof based on OTDR (optical time domain reflectometry) technique

The invention relates to a crack monitoring sensor and use method thereof based on an OTDR (optical time domain reflectometry) technique, and belongs to the technical field of monitoring of optical fibers. The crack monitoring sensor comprises a protection box, a bare optical fiber coil, a first optical fiber with a protecting layer, and a second optical fiber with a protecting layer, wherein the bare optical fiber coil is provided with two end joints, the bare optical fiber coil is an optical fiber coil which is formed by winding and knotting a bare optical fiber, and the diameter of the bare optical fiber coil is 14mm to 16mm. When the crack monitoring sensor is used, firstly, the outer optical fiber of the sensor is welded with the first optical fiber with the protecting layer and the second optical fiber with the protecting layer through the end joints, secondly, the adhering function of epoxy resin adhesive is released by an adhesive release agent, so that the inner optical of the sensor is ensured to be freely stretched along with the extension of the crack, and then the concrete is cast. The crack monitoring sensor and the use method have the advantages that the construction is convenient, the manufacturing is simple, the cost is low, the crack monitoring sensor and the use method are suitable for monitoring the cracks of various types of concrete inner structures, meanwhile, the operability is high, and the real-time monitoring and the distributed monitoring on the concrete inner structures are realized.