Formwork trolley with folding arc-shaped arch slab and construction method and contracting folding method of formwork trolley

The invention discloses a formwork trolley with a folding arc-shaped arch slab. The formwork trolley of the folding arc-shaped arch slab comprises the arc-shaped arch slab and a door frame; the arc-shaped arch slab comprises a plurality groups of arc-shaped arch slab units mutually connected in a hinged mode, the distance between the arc-shaped arch slab units and the door frame is adjusted by thearc-shaped arch slab units through oil cylinders, when contraction is carried out, the arc-shaped arch slab units can be arranged on the door frame in a foldable mode; and when stretching is carriedout, the arc-shaped arch slab units are fixedly supported on the door frame through detachable supporting pieces, and a contractible and folding mode can be simultaneously suitable for two kinds of tunnel concrete two-lining concrete with fracture surfaces with great differences. According to a construction method for widening fracture surface two-lining concrete in a tunnel, the construction progress of a widening section