Displacement-adjustable telescopic device and adjusting method

The invention relates to the field of bridge telescopic devices, in particular to a displacement-adjustable telescopic device and an adjusting method. The bridge expansion device comprises comb-tooth edge beams (3), wherein the comb-tooth edge beams (3) are symmetrically arranged, the ends of the two sides of the comb-tooth edge beams (3) are arc-shaped, and teeth of the comb-tooth edge beams (3) are staggered; the displacement adjuster (7) is of a groove-shaped structure, and the bottom of the displacement adjuster (7) comprises a long-strip-shaped hole, a round hole and an adjusting bolt (11) capable of penetrating through the long-strip-shaped hole and the round hole. The tenon-and-mortise type anchoring plate (1) and the tenon-and-mortise type supporting vertical plate (4) are connected below the comb tooth edge beam (3) on the left side; the tenon-and-mortise type anchoring plate (1) and the tenon-and-mortise type supporting vertical plate (4) are connected through mutually nested notches; by using the d