Insertion piece type tunnel joint displacement sensor

The invention discloses an insertion piece type tunnel joint displacement sensor, which comprises a distributed strain sensing optical fiber, a plurality of groups of insertion pieces, a fixed base and a trigger cushion block, and is characterized in that the insertion pieces are mounted on the fixed base, the fixed base is mounted on one side of a tunnel joint, and the trigger cushion block is mounted on the other side of the tunnel joint relative to the fixed base and is adjustable in height; the tips of the insertion pieces cross a tunnel joint and make contact with the triggering cushion block, the two adjacent sets of insertion pieces, the fixing base and the triggering cushion block are symmetrically arranged relative to the tunnel joint in a staggered mode, the distributed strain sensing optical fibers are symmetrically pasted to the front faces and the back faces of the insertion pieces, the multiple sets of insertion pieces are connected in series, and the distributed strain sensing optical fibers ar