Collapse prevention device for excavation of foundation pit of overhead line system foundation

The utility model relates to a catenary foundation pit excavation anti-collapse device which comprises first formworks, second formworks, pulleys, sliding grooves, connecting assemblies and a distance adjusting mechanism, the first formworks are oppositely arranged front and back, the through sliding grooves are symmetrically formed in the two ends of the inner side face of each first formwork, and the distance adjusting mechanism is arranged between the first formworks and the second formworks. Side blocking formwork sets formed by longitudinally connecting second formworks are arranged at the two ends between the two first formworks, the second formworks are connected through connecting assemblies, long adjusting shafts are symmetrically arranged on the left end face and the right end face of each second formwork, pulleys are fixedly installed on the heads of the long adjusting shafts, the second formworks slide up and down in sliding grooves of the first formworks through the pulleys, and the second formwo